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Snails and their trails: The multiple functions of trail-following in gastropods
Abstract
Snails are highly unusual among multicellular animals in that they move on a layer of costly mucus, leaving behind a trail that can be followed and utilized for various purposes by themselves or by other animals. Here we review more than 40 years of experimental and theoretical research to try to understand the ecological and evolutionary rationales for trail-following in gastropods. Data from over 30 genera are currently available, representing a broad taxonomic range living in both aquatic and terrestrial environments. The emerging picture is that the production of mucus trails, which initially was an adaptation to facilitate locomotion and/or habitat extension, has evolved to facilitate a multitude of additional functions. Trail-following supports homing behaviours, and provides simple mechanisms for self-organisation in groups of snails, promoting aggregation and thus relieving desiccation and predation pressures. In gastropods that copulate, trail-following is an important component in mate-searching, either as an alternative, or in addition to the release of water- or air-borne pheromones. In some species, this includes a capacity of males not only to identify trails of conspecifics but also to discriminate between trails laid by females and males. Notably, trail discrimination seems important as a pre-zygotic barrier to mating in some snail species. As production of a mucus trail is the most costly component of snail locomotion, it is also tempting to speculate that evolution has given rise to various ways to compensate for energy losses. Some snails, for example, increase energy intake by eating particles attached to the mucus of trails that they follow, whereas others save energy through reducing the production of their own mucus by moving over previously laid mucus trails. Trail-following to locate a prey item or a mate is also a way to save energy. While the rationale for trail-following in many cases appears clear, the basic mechanisms of trail discrimination, including the mechanisms by which many snails determine the polarity of the trail, are yet to be experimentally determined. Given the multiple functions of trail-following we propose that future studies should adopt an integrated approach, taking into account the possibility of the simultaneous occurrence of many selectively advantageous roles of trail-following behaviour in gastropods. We also believe that future opportunities to link phenotypic and genotypic traits will make possible a new generation of research projects in which gastropod trail-following, its multitude of functions and evolutionary trade-offs can be further elucidated.
... Tis behavior allows the snail to return to a safe location after foraging or mating, reducing the risk of predation and desiccation. Mucus trails also support homing behaviors in groups of snails [30]. ...
... Te mucus trails left by gastropods have the ability to bind microalgal cells, enabling them to collect and ingest microalgae, which in turn serves as a nutritional source for animals [32]. For a more comprehensive understanding of the various benefts of gastropod trails, the review by Ng et al. [30] provides an excellent resource. It delves deeper into the multifaceted roles these trails play in the life of gastropods and their interactions with other species. ...
... Te composition of mucus can also change based on the prevailing conditions and the specifc requirements of the gastropod [30,53]. For instance, gastropods inhabiting arid environments produce mucus with properties that help conserve water. ...
Gastropod mucus, a complex and versatile substance produced by snails and slugs, plays a critical role in their biology, and holds promise for various applications. This review offers a comprehensive and insightful overview of the current state of knowledge on gastropod mucus, encompassing its composition, biological roles, and potential applications. We delve into the multiple intricate mechanisms by which snails and slugs employ mucus to achieve their various biological goals such as locomotion, defense against predators, protection from environmental threats, communication, mating, homing behavior, nutrient recycling, and regulating population density. The focus then shifts to an examination of the practical applications of gastropod mucus such as antipathogen properties, skincare and antiaging, surgical adhesive and drug delivery, dental and orthopedic application, engineering, and biomimicry, as revealed through various studies. We also critically assess the results and identify areas for further research. This critical review helps to refine our understanding of the true potential of gastropod mucus and guides future investigations. Finally, we discuss the challenges of studying gastropod mucus.
... Howard 2001). Trails represent perhaps the most potent and targetoriented means for finding mates and food sources across taxa (e.g., social insects Wilson 1962;Jeanne 1981;Nieh et al. 2004;Jarau 2009;Bordereau and Pasteels 2010;Czaczkes et al. 2015), reptiles (Gehlbach et al. 1971;Cooper and Vitt 1986), mollusks (Cook and Cook 1975;Ng et al. 2013;Vong et al. 2019), and mammals (Jamon 1994;Harmsen et al. 2010)). By adding specific information to a trail (e.g., pheromones), the trail producer can inform the following conspecific about its sex, mating status, or body condition, allowing both advertisement of the producer and assessment by the trail follower (e.g., Gehlbach et al. 1971;Edwards and Davies 2002;O'Donnell et al. 2004; . ...
... Thus, any aid to the individual in determining the direction to follow, such as polarized trails embedded with directionality information, provides benefits (Cook and Cook 1975;Tietjen 1977;Rosengren and Fortelius 1987;Nieh et al. 2004). Embedded trail directionality appears to be rare as it has been described in only a few species (e.g., Gehlbach et al. 1971;Tietjen and Rovner 1980;Jackson et al. 2004;Nieh et al. 2004;Ng et al. 2013), and its respective encryption in the trail is understood in even fewer cases (Ford and Low 1984;Jackson et al. 2004). For example, snakes can encrypt trail polarity by sequentially touching a specific surface of ambient objects (e.g., anterolateral) with pheromone-secreting glands during movements (Ford and Low 1984). ...
... Trail directionality is, for example, not expected when the costs of trail deposition including embedding of directionality information, in terms of energetic costs (i.e., production and/or secretion of substances) or ecological costs (i.e., increased visibility to predators), override the benefits of finding the trail producer. The limited evidence for trail directionality may, however, also result from a small number of empirical studies focusing on few taxonomical groups (e.g., molluscan mucous trails and pheromone trails of ants) (Rosengren and Fortelius 1987;Jackson et al. 2004;Ng et al. 2013;Czaczkes et al. 2015), leading to bias in the literature. Hence, overall trail directionality remains poorly understood. ...
Mate search is challenging for solitary species. Trails represent a particularly potent, target-oriented means for finding mates, as trail-following increases encounter rates between individuals compared to random search. Embedding directionality information into the trail allows individuals to follow trails correctly to the source. Yet, directionality remains poorly understood. Spiders deposit trails during locomotion consisting of silk lines and substrate-borne chemicals. We conducted multiple experiments to test whether female silk trails convey directionality information, whether directionality is chemically or structurally encoded and depends on female phenotype. We also examined whether males interact with silk in a way that suggests information gathering. We exposed males of the cursorial spider Pisaura mirabilis to female trails deposited unidirectionally and scored their trail-following direction (i.e., same as or opposite to the females’). Tests were repeated after washing trails with a solvent to remove putative chemicals and by sourcing silk from females of different feeding regimes. While we found little evidence for male directional trail-following, we did find that unwashed trails were more likely to be followed than washed trails. Similarly, trails of relatively larger females were more likely to be followed correctly than those of smaller females. Males extensively probed and pulled on silk lines with their appendages, suggesting the gathering of chemical and tactile information. Taken together, results suggest that directional trail-following is selected only under specific contexts in this species. Chemical attributes of trails may convey information on female quality, with directional trail-following reflecting male mate choice in a system characterized by costly male nuptial gifts.
Significance statement
In the context of male mate search, following conspecific trails increases the chances of encountering a mating partner, especially if trails provide information about the direction the conspecific went. Yet, trail directionality remains poorly understood. Female spiders deposit silk trails as they walk. We overall show that males follow trails directionally only under a specific context. Males were more likely to follow correctly when trails were unmanipulated (compared to being washed with solvents to remove chemicals) and when they were deposited by relatively larger females (compared to smaller ones). Chemical attributes of trails may potentially indicate directionality, while decoding movement direction from trails of larger females may reflect male preferences for females of higher reproductive value.
... This allows close contact between the epithelia and substrate while reducing friction during muscular pedal waves that generate locomotor forces. 2,4,20 The mucus exhibits shear-thinning behavior, with viscosity decreasing under applied shear stress during movement. Rapid recovery of viscosity when strain is removed enables continuous gripping and release from the substrate. ...
... Rapid recovery of viscosity when strain is removed enables continuous gripping and release from the substrate. 4,20,21 The adhesive mucus has a higher protein content and specific "glue proteins", increasing gel strength and viscosity. 22 The mucus also provides a protective barrier against desiccation, mechanical damage, and pathogens. ...
... Terrestrial gastropods leave mucus trails that facilitate navigation, aggregation, and mate-finding. 4 Mucus may also allow gastropods to modulate plant biology through secreted bioactive compounds. 23,24 Some species use mucus directly for predator defense. ...
Terrestrial gastropod mucus exhibits multifunctional attributes, enabling diverse applications. This comprehensive review integrates insights across biomedicine, biotechnology, and intellectual property to elucidate the bioactivities, physicochemical properties, and ecological roles of snail and slug mucus. Following an overview of mucus functional roles in gastropods, promising applications are highlighted in wound healing, antimicrobials, biomaterials, and cosmetics, alongside key challenges. An analysis of global patent trends reveals surging innovation efforts to leverage gastropod mucus. Strategic priorities include bioprospecting natural diversity, optimizing stabilization systems, recombinant biosynthesis, and fostering collaboration to translate promising potentials sustainably into impactful technologies. Ultimately, harnessing the remarkable multifunctionality of gastropod mucus holds immense opportunities for transformative innovations in biomedicine, biotechnology, and beyond.
... Molluscs, including terrestrial gastropods (slugs, snails), are exposed to what can be considered as a landscape of disgust. The terrestrial gastropod snail, Cepaea nemoralis, may encounter various pathogens and potential infections and contaminants while navigating through its environment and feeding on plant material (Chang, 1991;Dahirel et al., 2022;Ng et al., 2013;Pakarinen, 1992aPakarinen, , 1992b. Non-volatile and volatile components of the mucus produced by snails during locomotion are used for communication (Ballard et al., 2021;Bull et al., 1992;Chase et al., 1978;Ng et al., 2013), and may provide cues to an individual's immunological and infection status. ...
... The terrestrial gastropod snail, Cepaea nemoralis, may encounter various pathogens and potential infections and contaminants while navigating through its environment and feeding on plant material (Chang, 1991;Dahirel et al., 2022;Ng et al., 2013;Pakarinen, 1992aPakarinen, , 1992b. Non-volatile and volatile components of the mucus produced by snails during locomotion are used for communication (Ballard et al., 2021;Bull et al., 1992;Chase et al., 1978;Ng et al., 2013), and may provide cues to an individual's immunological and infection status. Here, we investigated the responses of individual Cepaea to simulated infection threat presented by the mucous associated cues of individuals treated with a bacterial endotoxin lipopolysaccharide ((LPS), a cell wall component of Gram negative bacteria). ...
... Gastropod molluscs possess well developed olfactory systems that they use in a variety of behavioral functions, including the acquisition of information regarding identity and condition from non-volatile and volatile constituents of mucus (e.g., Chase et al., 1978;Holland et al., 2018;Kiss, 2017;Ng et al., 2013;Pakarinen, 1992aPakarinen, , 1992bSkingsley et al., 2000;Thomas et al., 1998). Terrestrial snails use olfaction as the principal sensory modality for perception at a distance. ...
Disgust is considered to be a fundamental affective state associated with triggering the behavioral avoidance of infection and parasite/pathogen threat. In humans, and other vertebrates, disgust affects how individuals interact with, and respond to, parasites, pathogens and potentially infected conspecifics and their sensory cues. Here we show that the land snail, Cepaea nemoralis, displays a similar “disgust-like” state eliciting behavioral avoidance responses to the mucus associated cues of infected and potentially infected snails. Brief exposure to the mucus of snails treated with the Gram-negative bacterial endotoxin, lipopolysaccharide (LPS), elicited dose-related behavioral avoidance, including acute antinociceptive responses, similar to those expressed by mammals. In addition, exposure to the mucus cues of LPS treated snails led to a subsequent avoidance of unfamiliar individuals, paralleling the recognition of and avoidance responses exhibited by vertebrates exposed to potential pathogen risk. Further, the avoidance of, and antinociceptive responses to, the mucus of LPS treated snails were attenuated in a dose-related manner by the oxytocin (OT) receptor antagonist, L-368,899. This supports the involvement of OT and OT receptor homologs in the expression of infection avoidance, and consistent with the roles of OT in the modulation of responses to salient social and infection threats by rodents and other vertebrates. These findings with land snails are indicative of evolutionarily conserved disgust-like states associated with OT/OT receptor homolog modulated behavioral avoidance responses to infection and pathogen threat.
... Odorants or chemicals released into the environment may play a crucial role in finding a host. Snails can track their mating partners using water-or air-borne pheromones, and mucus trails (Ng et al., 2013). A particular larval stage of the mite Myianoetus muscarum is attracted to a volatile substance produced by the pupa of the fly Muscina stabulans. ...
... The ability to emit chemical signals is known from various invertebrates, on which C. elegans has been repeatedly found. Snails are known to release substances with their mucus that enable other snails to follow their tracks (Ng et al., 2013). Isopods such as Armadillidium vulgare use chemical signals to attract mating partners (Beauché and Richard, 2013). ...
... Since mucus plays a role in communication between snails and their Frontiers in Ecology and Evolution 05 frontiersin.org conspecifics (Ng et al., 2013;Vong et al., 2019) and is therefore also a potential source of attraction for C. elegans, the attraction of mucus from the foot of Arion sp. was tested as potential attractant in the chemotaxis assay. We found that Arion sp. ...
Some small animals migrate with the help of other, more mobile animals (phoresy) to leave short-lived and resource-poor habitats. The nematode Caenorhabditis elegans lives in ephemeral habitats such as compost, but has also been found associated with various potential invertebrate vectors. Little research has been done to determine if C. elegans is directly attracted to these invertebrates. To determine whether C. elegans is attracted to compounds and volatile odorants of invertebrates, we conducted chemotaxis experiments with the isopods Porcellio scaber, Oniscus asellus, and Armadillidium sp. and with Lithobius sp. myriapods, Drosophila melanogaster fruit flies, and Arion sp. slugs as representatives of natural vectors. Because phoresy is an important escape strategy in nature, especially for dauer larvae of C. elegans, we examined the attraction of the natural C. elegans isolate MY2079 in addition to the laboratory-adapted strain N2 at the dauer and L4 stage. We found that DMSO washing solution of Lithobius sp. and the odor of live D. melanogaster attracted C. elegans N2 L4 larvae. Surprisingly, the natural isolate MY2079 was not attracted to any invertebrate during either the dauer or L4 life stages and both C. elegans strains were repelled by various compounds from O. asellus, P. scaber, Armadillidium sp., Lithobius sp., and Arion sp. feces. We hypothesize that this is due to defense chemicals released by the invertebrates. Although compounds from Lithobius sp. and D. melanogaster odorants were mildly attractive, the lack of attraction to most invertebrates suggests a predominantly opportunistic association between C. elegans and invertebrate vectors.
... Previous reviews have extensively covered the functions of mucus trails that many gastropods secrete (Ng et al. 2013), as well as the anatomy and physiology behind their use of olfactory cues for navigation (Wyeth 2019). A handful of studies have explored chemical communication in terrestrial gastropods (e.g., Lefcort et al. 2006;Bursztyka et al. 2018), but to my knowledge, no studies have attempted to test if freshwater gastropods can detect and respond to chemical cues in terrestrial environments. ...
... Mucus trails have been most heavily studied in marine gastropods, but a few species of freshwater gastropod have been studied as well. Mucus trails contain chemicals that can indicate individual sex and species identity, both of which are useful for mate location (Ng et al. 2013). Pomacea canaliculata is capable of following mucus trails of other adult conspecifics, but it does not appear to be able to distinguish trail directionality (Takeichi et al. 2007). ...
... In Physa gyrina, food-deprived individuals are more likely to follow the trails of fed conspecifics, while fed individuals are more likely to avoid those trails (Larcher and Crane 2015). A broader discussion of known functions of mucus trails across all gastropods is reviewed by Ng et al. (2013). ...
Freshwater gastropods occupy relatively low trophic levels in food webs and are frequently consumed as prey items by a wide variety of predators. Many studies have documented these organisms’ abilities to utilize chemical cues to make decisions relating to growth, reproduction, and behavior. Chemical communication in these species has been studied in terms of transmission and detection within only one environmental medium (i.e., water) despite there being some species that regularly cross barriers between media that may be capable of—and benefit from—detecting chemical cues in both aquatic and terrestrial environments. Previous gastropod reviews have focused heavily on mucus trails (Ng et al. in Biol Rev 88:683–700, 2013) and the anatomy and physiology behind gastropod olfactory navigation (Wyeth in J Exp Biol, https://doi.org/10.1242/jeb.185843, 2019). In this review, I discuss how freshwater gastropods respond to a variety of conspecific and heterospecific cues, and the known—or potential—ecological implications of these responses. I present several directions for future research to further explore chemical cue detection in both air and water as well as the ways in which freshwater gastropod communication may interact with the broader ecological community, particularly in the context of predation.
... brood care, nest building, division of labour) has been largely studied. In intertidal invertebrates in general, and gastropods in particular, the most studied behaviour is trail-following (i.e. when individuals follow the tracks or paths of other individuals; see Ng et al., 2013 for a review). Trail-following in gastropods have multiple roles such as mate location (i.e. ...
... Trail-following in gastropods have multiple roles such as mate location (i.e. locating the right species, the right sex, hence facilitating sexual selection), nutrition (predatory snails follow the trails of other snails, or snails can feed on particles on mucus trails) and energy conservation (by re-using previously laid trails), and both aggregation and homing behaviour (Ng et al., 2013). However, many homing species do not necessary return to their resting site via the same path as they left and thus do not only used trail-following. ...
... Specifically, Seuront et al. (2018a) suggested that intertidal snails are likely using a variety of directional cues to accomplish such directed movements. Numerous directional cues have been observed in intertidal snails such as chemotaxis 1 (see Croll (1983) and Ng et al. (2013) for reviews), rheotaxis 2 (Overholser, 1964;Neale, 1965;Crisp, 1969;Duch, 1971;, phototaxis 3 (Charles, 1961;, scototaxis 4 (Moisez and Seuront, 2020) or geotaxis 5 (Kanda, 1916;. However, a recent work highlighted the fact that, when Littorina littorea individuals encountered a topographical discontinuity in their environment, individuals consistently followed it before moving to a geotactic response. ...
Intertidal organisms inhabit highly variable and complex environments and are submitted to a large range of stimuli and stresses. Recently, new insights into the sensory abilities of intertidal gastropods and their subsequent ability to navigate through topographically complex landscapes demonstrated that the behavioural repertoire of intertidal gastropods is much wider than previously thought. In this context, the present thesis first aimed to ameliorate our knowledge in the thigmotactic behaviour of Littorina littorea. Specifically, thigmotactic behaviour was tested in experimental containers of different sizes and shapes. This approach allowed individuals to encounter two-dimensional and three-dimensional discontinuities in order to understand how the topographical complexity of their environment can modify this behaviour. Thigmotaxis was further tested under decreasing salinity concentrations to understand how salinity can modify gastropods behaviour, since they are typically submitted to large salinity variations during emersion periods. During emersion, intertidal organisms are also submitted to large temperature variations (up to 20°C). Thus, this work also investigated the thermal behaviour of intertidal gastropods by studying body temperature of L. littorea and Patella vulgata and their microhabitat temperature on a rocky platform on the French coasts of the eastern English Channel. Temperatures were investigated on four sunny days from June to December to test the microhabitat choice of these two intertidal gastropods species under temperature conditions typically experienced through a seasonal cycle on the Opal Coast. Aggregation behaviour in L. littorea and the associated thermal benefits previously found in gastropods literature were also investigated, (i) in situ under a moderate heat wave and (ii) ex situ under an extreme heat wave simulated under laboratory-controlled conditions. Specifically, the body temperature of individuals inside and at the edge of aggregates were investigated to assess the importance of the position within aggregates.Taken together, the results of this thesis suggest that the thigmotactic behaviour can be one of the major taxes involved in intertidal gastropods orientation. Indeed, even under unfavourable conditions (e.g. low salinity conditions), the thigmotactic behaviour is still observed in L. littorea. This work also highlighted macrohabitat preference in L. littorea and P. vulgata for biogenic structures which allow to reduce both desiccation and thermal stresses. Within a macrohabitat, intertidal organisms are able to take advantage of the thermal mosaic encountered in intertidal environment and select microhabitat. This microhabitat selection in gastropods, is species- temperature- and habitat-dependent and allows individuals to maintain their body into their optimal range of temperatures. Finally, this work stressed the absence of thermal benefits of being aggregated in L. littorea under heat stress conditions. Specifically, under extreme heat wave, body temperature of individuals inside the aggregate is higher than for individuals at the edge of the aggregate. This result raised the rather unexpected and still unresolved question to understand the mechanisms driving aggregation behaviour in L. littorea. These results nevertheless contribute to the growing evidence that studying behaviour in intertidal gastropods is critical to understand how they move, how they perceive their environment and how they cope with raising temperature under global warming. This work also highlighted the importance of a better understanding of the thermoregulatory behaviour in intertidal organisms, for a better estimation of the impact of global warming in their ecology.
... Snails in the family Littorinidae, being abundant and important herbivores in high-shore environments worldwide (reviewed by McMahon, 1990McMahon, , 2001McQuaid, 1996;Reid, 1989), are excellent models to investigate the strategic partitioning of behaviors that allow successful utilization of these extreme habitats. These snails exhibit various behaviors common to many mobile intertidal ectotherms such as trail following, refuge selection, aggregation, and as they undergo internal fertilization, mating and fighting for mates (see Cartwright & Williams, 2012;Ng et al., 2013Ng et al., , 2016Stafford et al., 2007). They also perform shell-posturing behaviors, for example standing and towering (Marshall & Chua, 2012;Marshall, Mustafa, et al., 2010;Seuront & Ng, 2016). ...
... They also perform shell-posturing behaviors, for example standing and towering (Marshall & Chua, 2012;Marshall, Mustafa, et al., 2010;Seuront & Ng, 2016). Some of these behaviors are known to have multiple functions; trail following, for example, is associated with foraging, mating, energy saving, and aggregation formation (reviewed by Ng et al., 2013). ...
... Most previous studies (e.g. Cartwright & Williams, 2012;Ng et al., 2013Ng et al., , 2016Seuront & Ng, 2016;Stafford et al., 2007) have, however, only investigated the importance of a single function at a given time and have not considered how these snails can vary their behavioral repertoires to optimize the partitions between energy gain, reproduction, and amelioration of thermal stress in the extreme conditions of the high shore. To address this, we investigated variation in the behavioral repertoire, in terms of activity budget and utilization of multifunctional behaviors, of two high-shore species, Echinolittorina malaccana and E. radiata, in Hong Kong. ...
Abstract Species that inhabit high‐shore environments on rocky shores survive prolonged periods of emersion and thermal stress. Using two Hong Kong high‐shore littorinids (Echinolittorina malaccana and E. radiata) as models, we examined their behavioral repertoire to survive these variable and extreme conditions. Environmental temperatures ranged from 4°C in the cool season to 55.5°C in the hot season, with strong seasonal and daily fluctuations. In the hot season, both species allocated >35% of their activity budgets to stress‐mitigating thermoregulatory behaviors (e.g. standing, towering) and relatively small proportions to foraging (
... strength of preference, magnitude of size bias, and so on) depend on several interacting contextual factors. In many gastropod species, males employ mucus trail following to locate and choose mates, from which they may acquire fitnessrelevant information (such as the female's size and parasite load) before coming into any physical contact with the female (see Ng et al., 2013). In E. malaccana, this mate-assessing behaviour is supported by the observation that males trail-follow females specifically (the reverse is infrequent, particularly during rising tides) and most eventually mount and mate with the followed females (Ng et al., 2019). ...
... In E. malaccana, this mate-assessing behaviour is supported by the observation that males trail-follow females specifically (the reverse is infrequent, particularly during rising tides) and most eventually mount and mate with the followed females (Ng et al., 2019). Such a mechanism of employing mucus trail following for reproductive purposes aids the efficiency of exhibiting mate choice in gastropods, particularly when there are low densities of conspecifics or there is a limited time window to mate (Ng et al., 2013). The common use of trail following by males to search for mates may, in part, contribute to the general mate choice for size pattern seen in many marine gastropod species (Ng et al., 2019). ...
Echinolittorina malaccana, a marine gastropod living on rocky shores along the Indo-West Pacific coasts, shows consistent mate choice in which males prefer to mate with females slightly larger than themselves. Previous studies suggest that the strength of this preference is, to a certain extent, context dependent, being influenced by both demographic and individual (potentially genetic) factors. To disentangle how exactly these factors contribute to male mate choice for size in E. malaccana, we employed modified versions of a previous mate choice experiment using a range of female and male size classes. Mate choice was measured from the same male individuals across different experimental days, thus allowing the analysis of the repeatability of male preferences, as well as the comparison of the strength of mate choice with previous experimental designs and data from wild populations. Two parallel experiments (presenting either the same or different female individuals to males across days) were conducted, which allowed the inference of whether size alone, or additionally with other traits, influences mate choice. Results showed that male preference for females slightly larger than themselves remained consistent in both experiments, although its specific characteristics (e.g. strength of preference, extent of size bias) differed from previous studies. This suggests that the estimation of mate choice in E. malaccana is sensitive to experimental approaches and, to a certain extent, context dependent. The repeatability of mate choice (0–0.36) was only significant in the experiments where males were presented with the same female individuals. Mate choice is, therefore, primarily based on size, but other factors such as female quality or imprinting may modify this choice and lead to discrepancies in repeatability between experiments.
... Land snail mucus provides a ready-made substrate for communication, which generally involves trail following. Within a species, following trail mucus aids in finding mates, homing, and aggregation (Ng et al., 2013). Following trails may also reduce mucus use, saving both energy and water (Davies & Blackwell, 2007), although such savings are not always the case (Cook, 1992). ...
... C. aspersum (without Rumina decollata) 5. Do individuals of C. aspersum from the lab colony previously exposed to R. decollata avoid the mucus of R. decollata, a facultative snail predator? in intertidal limpets and chitons (reviewed by Chelazzi, 1990;Ng et al., 2013). Alternatively, aggregation may occur because of a shortage of sheltering locations rather than as an intentional behavior (Schweizer et al., 2019;Tomiyama, 1992). ...
Mucus is applied to substrates as snails move and when they rest. Beyond the use of mucus in movement and adhesion, the wide array of chemicals in mucus allows for supplemental use in communication. This communication is apparent in trail‐following behavior. This study addresses the potential communication via mucus in selecting resting sites in a laboratory assay. In a series of six experiments, individuals of Cornu aspersum (which often rest on above‐ground surfaces) were placed into lidded plastic containers with three or four sections swabbed with water (the control) or mucus, which included the test snail's own mucus, mucus from conspecifics from the same or a different container holding snails from the same lab colony, or from a different colony, and mucus from three additional snail species. The resting location was recorded on the following day. In two additional experiments, the facultative predator Rumina decollata was tested against conspecific and other snails' mucus. Individuals of C. aspersum preferentially rested in areas with the mucus of familiar conspecifics over mucus of unfamiliar conspecifics, a behavior that may contribute to homing and aggregation behaviors. There was evidence that juveniles may be less selective than adults. The mucus of only one of the three other species was avoided by individuals of C. aspersum . Unlike individuals of C. aspersum , individuals of the predator R. decollata avoided the mucus of conspecifics, which may be associated with less need for mate‐finding in this self‐fertilizing species. Individuals of R. decollata did not select among potential prey species.
... Literature studies indicated the effects of snail secretion by inducing fibroblast proliferation and enhancing wound healing. 32,33 In our previous study, we fabricated mucus and slime extract loaded single-layer porous chitosan scaffolds for bone and cartilage tissue regeneration separately. We investigated the effects of different mucus and slime extract loading percentages on each scaffold in terms of physical characteristics and bioactivity. ...
... Allantoin; collagen; elastin; glycolic acid; GAG; and vitamins A, E, and C are among the many components found in the mucus and slime that snails secrete. 32,33 These components may stimulate the synthesis of COMP and GAG for ECM formation. Figure 8 shows the COMP and GAG secretion of SW1353 cells incubated on CHI-M and CHI-S gradient scaffolds. ...
Regeneration of osteochondral tissue with its layered complex structure and limited self-repair capacity has come into prominence as an application area for biomaterial design. Thus, literature studies have aimed to design multilayered scaffolds using natural polymers to mimic its unique structure. In this study, fabricated scaffolds are composed of transition layers both chemically and morphologically to mimic the gradient structure of osteochondral tissue. The aim of this study is to produce gradient chitosan (CHI) scaffolds with bioactive snail (Helix aspersa) mucus (M) and slime (S) extract and investigate the structures regarding their physicochemical, mechanical, and morphological characteristics as well as in vitro cytocompatibility and bioactivity. Gradient scaffolds (CHI-M and CHI-S) were fabricated via a layer-by-layer freezing and lyophilization technique. Highly porous and continuous 3D structures were obtained and observed with SEM analysis. In addition, scaffolds were physically characterized with water uptake test, micro-CT, mechanical analysis (compression tests), and XRD analysis. In vitro bioactivity of scaffolds was investigated by co-culturing Saos-2 and SW1353 cells on each compartment of gradient scaffolds. Osteogenic activity of Saos-2 cells on extract loaded gradient scaffolds was investigated in terms of ALP secretion, osteocalcin (OC) production, and biomineralization. Chondrogenic bioactivity of SW1353 cells was investigated regarding COMP and GAG production and observed with Alcian Blue staining. Both mucus and slime incorporation in the chitosan matrix increased the osteogenic differentiation of Saos-2 and SW1353 cells in comparison to the pristine matrix. In addition, histological and immunohistological staining was performed to investigate ECM formation on gradient scaffolds. Both characterization and in vitro bioactivity results indicated that CHI-M and CHI-S scaffolds show potential for osteochondral tissue regeneration, mimicking the structure as well as enhancing physical characteristics and bioactivity.
... The use of LatA as a semiochemical in the mucus trail could simultaneously inform and attract mating partners, while deterring predators from trying to follow the trail. For gastropods, the production of mucus is vital, but costly, and several behavioral adaptations, such as trail following, have evolved to compensate for energy losses [21,28,162]. However, leaving a trail poses a risk, as it reveals the position not only to mating partners, but also to predators. ...
... However, leaving a trail poses a risk, as it reveals the position not only to mating partners, but also to predators. It has been shown that gastropod conspecifics and predators alike can pick up various cues, allowing them to determine the polarity (i.e., direction) of the trail and follow it to the mucus-producing organism [21,28]. Many, but not all, Chromodoris nudibranchs are known to display bright and contrasting coloration where MDFs are distributed in the mantle tissue, thus acting as visual signals, such as aposematic coloration and the use of mimicry, to advertise their toxicity [11,[18][19][20]125,128,129,160,163]. ...
Five Chromodoris species from North Sulawesi, Indonesia, were investigated for their sequestration of marine natural products. The cytotoxic 2-thiazolidinone macrolide latrunculin A (LatA) was the major metabolite in all examined Chromodoris species, as well as in one of the associated sponges Cacospongia mycofijiensis (Kakou, Crews & Bakus, 1987), supporting a dietary origin of LatA. Furthermore, LatA was secreted with the mucus trail, suggesting a possible use in short-range chemical communication. MALDI MS-Imaging revealed an accumulation of LatA throughout the mantle tissue, mucus glands, and especially in vacuoles of the mantle dermal formations (MDFs). Cytotoxicity of the isolated LatA was tested in HEK-293 cells, confirming that LatA targets the actin cytoskeleton. In vivo toxicity experiments with the sacoglossan Elysia viridis (Montagu, 1804) showed 100% mortality, but 100% survival of Chromodoris specimens, demonstrating resistance to LatA. A novel actin isoform was detected in all investigated Chromodoris species with two amino acid substitutions at the ‘nucleotide binding’ cleft, the binding site of LatA. These are suggested to cause insensitivity against LatA, thus enabling the storage of the toxin within the body for the slugs’ own defense.
... Secondly, loping has never been reported in context of prey-predator interaction. However, some predators (frequently predator snail) track their snail prey by following their mucus trail (Ng et al. 2013). The discontinuous trail associated to loping could confound trail-following predators (Pearce, 1989;McKee et al., 2013;Ng et al. 2013). ...
... However, some predators (frequently predator snail) track their snail prey by following their mucus trail (Ng et al. 2013). The discontinuous trail associated to loping could confound trail-following predators (Pearce, 1989;McKee et al., 2013;Ng et al. 2013). ...
Loping behaviour is a mode of locomotion in land gastropods, in which the animal creates arches with its foot, notably to minimize body contact with a dry substrate. Although this behaviour has been known since the early 1900s, few species have been reported adopting it (14 species-snails or slugs). Here we introduce our observation of loping behaviour in Hygromia cinctella (Draparnaud, 1801), a species not yet known to adopt this particular mode of locomotion. This behaviour is here induced by a substract of dry limestone. A typical discontinuous slime trail linked to this loping behaviour is observed. Hygromia cinctella is able to adopt only one body elongation wave, with at times a temporary "tip-toe" posture, thereby limiting its contact with the substrate to only 25% of the body length. This result is currently a record for science, the number of elongation waves being usually between 1 and 2. Based on data in literature [in particular for Cornu aspersum (O. F. Müller, 1774)], one may suppose that the number of elongation waves (and number of arches) is probably dependent on the snail size, but that the proportion of foot in contact with the substrate is not. It appears to be confirmed that a full adhesive crawling is related to smooth and nonporous surface while loping is associated to more rough, porous and absorbent surface.
... Speiser and Hochstrasser (1998) showed that with higher soil moisture, slugs were more active, resulting in higher herbivory levels and Nicolai and Ansart (2017) state that drought and higher temperatures might decrease slug activity. Various gastropod species including terrestrial snails and slugs show homing behavior, where they return to a microsite with favorable conditions (shelter) (Edelstam and Palmer 1950, Gelperin 1974, Rollo and Wellington 1981, Ng et al. 2013. This homing behavior increases under adverse environmental conditions, such as increasing temperatures and evapotranspiration (Rollo andWellington 1981, Prior 1985). ...
... Slugs spend considerable time in their shelter and often return to shelters (Edelstam and Palmer 1950, Gelperin 1974, Rollo and Wellington 1981, Ng et al. 2013. They also prefer seedlings as valuable resources (Honek et al. 2009, Strauss et al. 2009). ...
The outcome of seed fate (probability of predation or dispersal) depends on the interplay between granivores and seed traits. Furthermore, changing environmental conditions affecting granivore behavior might additionally alter seed dispersal patterns.
Based on microcosm experiments and time‐lapse videos, we tested in a structural equation model how dry or wet conditions in a slug–legume seed system affect slug movement behavior, thus influencing seed encounter, ingestion and dispersal locations. We additionally analyzed how interactions between slug weight, chemical and morphological seed traits determine the fate of ingested seeds and used point pattern analysis of seed locations to detect potential dispersal patterns.
While dry or wet conditions had no direct effect on the time slugs spent moving, dry conditions significantly increased the slug's homing behavior. Higher slug movement increased the chance of seed encounter, smaller seeds with low seed coat permeability were preferably ingested and the proportion of ingested seeds increased with increasing seed oil content. A high proportion of ingested seeds was dispersed via endozoochory, but none of the tested seed traits could explain seed fate.
Endozoochory led to clumped dispersal patterns around the slug's shelter with clustering significantly more pronounced for seeds in dry conditions due to increased homing behavior in slugs. These dispersal patterns indicate potential directed dispersal to moist microsites but whether this leads to higher recruitment and hence successful directed dispersal remains to be tested.
... Experimental and theoretical rationales regarding the purpose of land snail trail mucus have been an important area of research for more than 40 years [41][42][43][44]. Obtaining knowledge as to why snails produce mucus for locomotion, adhesion, reproduction, aggregation, and various other functions has been integral to the elucidation of their ecological and evolutionary development. ...
Invasive invertebrate pests have become a major threat to food security as global populations increase. Pesticides, often containing organophosphates, have long been used as agents for providing immediate short-term recovery, yet are often broad-spectrum, leading to the development of resistance. In insect species, one mechanism for resistance is known to be driven by mutations in acetylcholinesterase (AChE), an enzyme that catalyses the hydrolysis of acetylcholine. In this study, we explored a potential role for resistance-modified AChE in invasive pest land snails, using the Mediterranean snail Theba pisana. Following tissue transcriptomic investigation, an expanded family of AChE-like genes were identified that clustered phylogenetically into three individual clades, with one clade including vertebrate AChE. The majority of T. pisana AChE-like genes demonstrated the highest expression in the snail mucous gland during its reproductive stage. Subsequent proteomic analysis of trail mucus at the reproductive stage identified four AChE-like proteins as a major component. Immunolocalisation revealed that AChE-like protein(s) were prominent in the mucous gland secretory cells and widespread throughout the reproductive stage trail mucus, yet were largely absent from trail mucus at the non-reproductive stage. In summary, this study established a potential role for resistance-modified AChE-like proteins in pest land snail pesticide resistance via their deployment into trail mucus that may bio-scavenge organophosphates, rendering them ineffective. Their abundance during the reproductive stage is likely due to the snail’s increased mobility, following periods of immobile aestivation.
... Home territories are formed when an individual centres around the use of a single refuge, which is thought to provide shelter from physical and abiotic stress (Chelazzi 1990). This instinct has long been believed to be associated with chemoreception and the following of "trails" deposited when an individual leaves a space previously designated as "home" (Ng et al. 2013). However, the garden snail, Cornu aspersum (O.F. ...
Slugs (Gastropoda: Stylommatophora) are common domestic garden inhabitants in the United Kingdom (UK) but few studies have explored the spatial behaviour of slugs within these habitats, largely due to limitations in available mark-recapture methodologies. Attempts to improve such methodologies for slugs have previously come at a high economic cost, short lifespan, and inability to detect slugs beneath the soil surface. The use of radio-frequency identification (RFID) technology has previously shown potential in overcoming these limitations, reducing the cost and impracticality of studying slug movement. However, this has yet to be applied to a domestic garden setting. This study explored the potential of RFID technology to track slug movement in a UK domestic garden. Both the common garden pests Deroceras reticulatum and Arion hortensis and the non-pestiferous Limacus maculatus were tagged with modest to no detrimental effects on survival at 62.5%, 25%, and 0% respectively. A novel method for the containment of D. reticulatum within a section of garden habitat was also assessed and found to be effective in containing 80% of slugs for a period of 67 days. RFID technology was able to identify the location of D. reticulatum amongst dense garden foliage and sub-soil for 67 days, enabling slug tracking within a domestic garden habitat. No homing instinct was identified in this study when attempting to induce a home territory over a period of 67 days for the species D. reticulatum. This study demonstrates the potential of RFID technology to track the locomotion of slugs in UK domestic garden habitats and provides an opportunity to update our knowledge on this subject by overcoming the methodological limitations associated with the high cost and impracticality of studying slugs.
... A unique feature of gastropods is their ability to secrete mucus that can be used to facilitate locomotion, homing, and mate-finding [10,11]. For example, the marine gastropod, Aplysia californica, secretes a mucus during egg-laying that contains a cocktail of proteinaceous pheromones to attract conspecifics for mating purposes [12][13][14][15]. ...
Mucus trails are defining features of the class Gastropoda, which includes snails and slugs. While several studies have shown that mucus trails are followed by conspecifics, the detectable elements in the mucus have not been clearly identified. This is particularly relevant during periods of reproduction, whereby conspecific cues are critical for mate finding. A better understanding of the mucus’ molecular components, including proteins differentially represented between the reproductive and non-reproductive stages, could aid the development of novel eco-friendly biocontrol approaches. In this study, we investigated the mucus trails of the globally invasive land snail Cernuella virgata, which has become a significant pest to the grain industry. We conducted a comparative proteomic analysis of the non-reproductive- and reproductive-stage trail mucus, whereby 533 proteins were identified, including 191 and 226 stage-exclusive proteins, respectively. Subsequent comparative tissue transcriptomic analysis found that the albumen gland, which is the key gland for the preparation of fertilized eggs prior to egg laying, was the primary source of secreted proteins present in the reproductive stage trail mucus. This included leukocyte elastase inhibitors, achacin, perlucin, and other proteins without any known function (uncharacterized). In summary, our results strongly implicate the albumen gland as a source for snail trail mucus proteins deposited during the reproductive stage, suggesting a mechanism that could convey their reproductive status to conspecifics. Further research testing their bioactivity related to chemical communication is paramount and may assist in the development of a novel biocontrol strategy.
... Their prey organisms, such as opisthobranchs, nematodes, platyhelminths, annelids, and gastropods, secrete mucus which serves a dual role in locomotion and defence (Blair and Seapy, 1972;Brusca and Brusca, 2003). Aglajids, including members of the Chelidonura genus, detect these mucus trails using specialised sensory organs, allowing them to hunt down mobile prey and feed on it by ingesting it whole as they lack a radula (Paine, 1963;Rudman, 1978;Kohn et al., 1983;Davies and Blackwell, 2007;Ng et al., 2013). Notably, observations have indicated that Chelidonura species prefer epifaunal organisms, including flatworms, slugs, and shelled gastropods (Silva and Malaquias, 2016). ...
Chelidonura livida, commonly known as the blue velvet headshield slug, is a sea slug within the family Aglajidae of the phylum Mollusca. This species was first described by Yonow in 1994 from the Red Sea coast of Israel. It exhibits a wide distribution, ranging from Africa to the Indo-Pacific region, extending to the coasts of Japan. This study documents the first occurrence of C. livida from the Gujarat coast of India where the specimens were observed at dusk, moving through sand flats adjacent to a Halophila decipiens seagrass bed off the coast of Mithapur. This report provides a detailed morphological description of C. livida and offers comprehensive insights into its ecology. Observations include the species’ burrowing behaviour, feeding habits, prey preferences, and reproductive strategies. The addition of this species elevates the total count of sea slug species in Gujarat to 97.
... 9,10,15 Among animal-based sources, Helix aspersa, known as garden snail, has two secretions, namely, mucus (M) and slime (S), that have many ingredients convenient to the human body, such as collagen, allantoin, elastin, glycolic acid, vitamins A, E, and C, and GAG. 18,19 Slime is the secretion that snails leave behind during their movement, whereas mucus is the adhesive secretion produced from the epithelium of the dorsal and lateral foot of snails. 19 In our previous studies, we incorporated H. aspersa mucus and slime extracts in a CHI matrix and investigated the effects of snail extracts on biomaterials with physical, chemical, and in vitro bioactivity of the CHI matrix for bone and cartilage regeneration. ...
In recent years, there has been a notable shift toward exploring plant and animal extracts for the fabrication of tissueengineering structures that seamlessly integrate with the human body, providing both biological compatibility and physical reinforcement. In this particular investigation, we synthesized bilayer wound dressings by incorporating snail (Helix aspersa)secretions, comprising mucus and slime, into chitosan matrices via lyophilization and electrospinning methodologies. A nanofiber layer was integrated on top of the porous structure to mimic the epidermal layer for keratinocyte activity as well as acting as an antibacterial barrier against possible infection, whereas a porous structure was designed to mimic the dermal microenvironment for fibroblast activity. Comprehensive assessments encompassing physical characterization, antimicrobial efficacy, in vitro bioactivity,and wound healing potential were conducted on these bilayer dressings. Our findings revealed that the mucus and slime extract loading significantly altered the morphology in terms of nanofiber diameter and average pore size. Snail extracts loaded on a nanofiber layer of bilayer dressings showed slight antimicrobial activity against Staphylococcus epidermidis and Escherichia coli. An in vitro release study of slime extract loaded in the nanofiber layer indicated that both groups 1 and 2 showed a burst release up to 6 h,and a sustained release was observed up to 96 h for group 1, whereas slime extract release from group 2 continued up to 72 h. In vitro bioactivity assays unveiled the favorable impact of mucus and slime extracts on NIH/3T3 fibroblast and HS2 keratinocyte cell attachment, proliferation, and glycosaminoglycan synthesis. Furthermore, our investigations utilizing the in vitro scratch assay showcased the proliferative and migratory effects of mucus and slime extracts on skin cells. Collectively, our results underscore the promising prospects of bioactive snail secretion-loaded chitosan constructs for facilitating skin regeneration and advancing wound healing therapies.
... When making immediate decisions, such when and where to grow a particular crop or which fields to irrigate, the data from the digital photos received may be retrieved, analyzed, and coupled with the data from the signals. At agricultural control centres, sensor and imaging data are merged with other data to help growers identify crops that require attention and choose which herbicides, water treatments, and fertilizers are most effective [14][15][16][17]. Larger businesses with the resources to invest in the IT infrastructure and other technical tools required to completely understand and reap the benefits of PA have historically been the only ones allowed to use it. ...
Agriculture is the study, practice, and science of plant growth. Agriculture has a long history dating back thousands of years. Depending on the topography and climate, it started out separately in different places of the planet. Thanks to agriculture, the number of people on Earth has increased many times beyond what could be maintained by hunting and gathering. Precision farming has improved production in modern agriculture since the 20th century. Precision farming is a farming method that uses technology to measure, monitor, and analyze the demands of particular fields and crops. The primary goal of this farming style, in contrast to conventional farming, is to maximize crop yields and profitability by precisely using inputs. In today's world, artificial intelligence and the Internet of Things are indispensable. Modern agriculture uses AI and IoT technologies and their benefits. This improves the accuracy and profitability of contemporary agriculture. We go over a few of the modern uses of AI and IoT in intelligent precision farming. Furthermore, significant instruments and methods used in precision farming are also described. The crucial benefits and the real-time devices used in the precision farming are also discussed in detail.
... Whereas production and secretion of mucus require a considerable energy cost (Davies et al. 1990, Davies andHawkins 1998), the mucus layer serves various functions in gastropods (reviewed in Bubel 1984;Voltzow 1994; Davies and Hawkins 1998;Avila and Angulo-Preckler 2020), including slip resistance for locomotion (Denny and Gosline 1980) and suspension-feeding (Kappner et al. 2000), as well as chemical defense against predation and infection. The mucus trail has multiple functions such as homing, mate location, and communication among conspecifics (reviewed in Ng et al. 2013), and some nudibranch sea slugs follow the mucus trails of their prey nudibranchs for predation (Paine 1963;Nakano and Hirose 2011). Moreover, aeolid sea slugs produce mucus that inhibits the discharge of nematocysts of their cnidarian prey (Greenwood et al. 2004). ...
... To deal with these varying conditions, mobile animals can employ movement as a strategy to evade both environmental and biotic challenges (Bach and Hazlett 2009). However, animals with limited mobility face significant constraints in actively escaping hostile conditions (Denny 1980;Ng et al. 2013). For slow-moving animals, it is therefore morphological and functional adaptations, rather than dispersal, that allow them to effectively cope with varying environmental conditions, including variations in temperature, hydrodynamic effects, desiccation, salinity, oxygen concentrations, food availability, and predation (Stillman and Somero 2000;Bird et al. 2013;Johannesson 2016). ...
Inhabitants of rocky intertidal shores, including gastropods, require specific adaptations to cope with numerous challenges that vary across the intertidal levels. We collected Stramonita biserialis snails from upper (wave-protected and intense predation) and lower (wave-exposed and low predation) intertidal sites to compare the following traits: shell skeleton (ventral and abaxial lateral views of shell shape, thickness, and mass), foot size, energy metabolism, and attachment strength to determine whether the trait values of snails from each zone fit the environmental challenges they face. We used a Principal Component Analysis to reduce the dimensionality of the data. Multivariate Analysis of Covariance (MANCOVA) for comparing characteristics between the two intertidal zones, and Partial Least Squares (PLS) analyses for testing the integration of overall snail characteristics. The traits of the snails of the two intertidal sites matched with the adaptations expected to allow them to cope with their contrasting challenges. The snails from the lower intertidal had more streamlined shells (which reduces drag forces) and a larger aperture and foot extension (which increase the strength of their attachment to the substrate) compared to snails from the upper sites. Snails from the lower intertidal also had a high mass-specific metabolism and soft body proportion, indicating that these snails from the wave-exposed sites have an energetically active musculature that matches their strong substrate attachment. The thin shell walls of the snails of the lower intertidal match the relatively low predatory pressure there.
... In order to reduce the water evaporation rate and avoid predators, snails generally take shelter in cool and humid places where moisture is available. As the snails are basically trail following gastropods, it is important to mention that the production of mucus trails is the most energy costly component of the snail locomotion (Ng et al. 2013;Hawkins and Hartnoll 1983). Snails do have eyes however they are not able to see far neither they can identify the colors (Chernorizov et al. 1994). ...
In this paper, a novel Snail Homing and Mating Search (SHMS) algorithm is proposed. It is inspired from the biological behaviour of the snails. Snails continuously travel to find food and a mate, leaving behind a trail of mucus that serves as a guide for their return. Snails tend to navigate by following the available trails on the ground and responding to cues from nearby shelter homes. The proposed SHMS algorithm is investigated by solving several unimodal and multimodal functions. The solutions are validated using standard statistical tests such as two-sided and pairwise signed rank Wilcoxon test and Friedman rank test. The solutions obtained from the SHMS algorithm exhibited superior robustness as well as search space exploration capabilities with less computational cost. The real-world application of the SHMS algorithm is successfully demonstrated in the engineering design domain by solving three cases of design and economic optimization Shell and Tube Heat Exchanger (STHE) problem. The objective function value and other statistical results obtained using SHMS algorithm are compared with other well-known metaheuristic algorithms. For Solving STHE Case 1 the SHMS algorithm achieved 0.5–35% minimization of the total cost. For Case 2, 0.6–29% minimization of the total cost has been attained. Furthermore, for Case 3, 0.3%, 0.4% and 52% minimization of total cost is achieved when compared with the ARGA & CI, GA, and original study, respectively. The analysis regarding the convergence of the SHMS algorithm is discussed in detail. The contributions in this paper have opened up several avenues for further applicability of the algorithm for solving complex real-world problems.
... Assortative mating is an important barrier between the Spanish L. saxatilis Crab and Wave ecotypes [64]. It likely emerged as a result of divergent selection on size, coupled to size-assortative mating, wherein size-assortative mating is an ancestral trait shared among many snails [77]. The clear size difference between ecotypes associated with microhabitat choice in Spain [65] strengthens this mating barrier [24]. ...
... In terrestrial ecosystems, larvae of some species of the Lampyridae, Carabidae, and Elateridae families (Coleoptera) prey on land snails by attaching to the shell and injecting venom to weaken them or else by breaking open the shell with their strong mandibles (Sato, 2019;Symondson, 2004). These snail eaters search actively by tracking land snail mucus trails (Ng et al., 2013;Sato, 2019;Symondson, 2004); no obvious ambush predator of these land snails has so far been found. ...
... Gastropoda is one of the most important groups of Mollusca that has successfully overrun most of the continent (Koudenoukpo et al., 2020). They may be found in a wide range of environments across the world, ranging from a defined aquatic environment to a more indeterminate terrestrial one (Kappes & Haase 2012;Ng et al., 2013;Vermeulen et al., 2015;Effendi et al., 2021;Al-Asif et al., 2022). It was found in aquatic habitats, such as lakes, rivers, marshes, streams, reservoirs, drainage, and other seasonal water bodies, among other places (Watson & Ormerod, 2004;Hill et al., 2016;Al-Asif et al., 2021). ...
Freshwater Gastropoda can be considered as the biological indicator in ecosystems such as rivers, streams, lakes, and ponds. The objectives of this study are to identify freshwater gastropod species, diversity, and distribution along Sungai Penebak, Sungai Nanga Tiga, and Sungai Kabo in the Betong division. The study was conducted on 10 November 2020. A 50 m transect was laid on the riverbank of all three stations. The existing specimens were counted and collected from each sampling point and stored were taken to the laboratory for species identification. The diversity index and morphological study of freshwater gastropods were performed. Five species of freshwater gastropods belonging to four families were discovered. The five species of freshwater gastropods consisted of Sulcospira pageli, which shows great abundance, followed by Clea nigricans, Brotia costula, Pila ampullacea, and Vittina pennata. The diversity indices of collected Gastropoda species from the different stations, for instance, Shannon Weiner diversity index (H’), Pielou’s evenness index (J’), and Margalef’s richness index were assessed; where station 3 showed higher diversity of Gastropoda compared to other two stations. The information presented in this paper might be helpful for ecological wealth studies and considered as the baseline data for the stream ecosystem in Sarawak, Malaysia.
... The silver trails were demonstrated to exhibit multiple functions, including the release of water-or airborne pheromones for mate searching. Some snails prefer to move over previously laid mucus trails to save energy and reduce production of their own mucus [10]. For either function, the formation of the coffee-ring effect in trail-followings should be inhibited. ...
Surface engineering of nanoparticles has been widely used in biosensing and assays, where sensitivity was mainly limited by plasmonic colour change or electrochemical responses. Here, we report a novel biomimetic sensing strategy involving protein-modified gold nanoparticles (AuNPs), where the modulation strategy was inspired by gastropods in inhibition of coffee-ring effects in their trail-followings. The so-called coffee-ring effect presents the molecular behaviour of AuNPs to a macroscopic ring through aggregation, and thus greatly improves sensitivity. The assay relies upon the different assembly patterns of AuNPs against analytes, resulting in the formation or suppression of coffee-ring effects by the different surface engineering of AuNPs by proteins and peptides. The mechanism of the coffee-ring formation process is examined through experimental characterizations and computational simulations. A practical coffee-ring effect assay is developed for a proof-of-concept target, amyloid β (1–42), which is a typical biomarker of Alzheimer’s disease. A novel quasi-titrimetric protocol is constructed for quantitative determination of the target molecule. The assay shows excellent selectivity and sensitivity for the amyloid β monomer, with a low detection limit of 20 pM. Combined with a fluorescent staining technique, the assay is designed as a smart sensor for amyloid β detection and fibrillation evaluation in rat cerebrospinal fluids, which is a potential point-of-care test for Alzheimer’s disease. Connections between amyloid fibrillation and different courses of brain ischaemia are also studied, with improved sensitivity, lower sample volumes that are required, convenience for rapid detection, and point-of-care testing.
... Benthic foraminifera are also able to produce mucus (e.g. [60]) of the same nature than gastropod mucus [61]. Besides allowing individuals to adhere to the substrate and move faster, mucus may also stabilize the sediment as particles are bound together by extracellular polymeric substance secreted by organisms [17,18,40,62]. ...
This study aimed to describe for the first time the vertical motion behaviour of the intertidal foraminifera Haynesina germanica and its contribution to bio-turbation. Its infaunal behaviour leads to the creation of a one-end tube within the first centimetre of sediment. In addition, a vertical trail following behaviour was described for the first time in foraminifera, which may be linked to the sustainability of the biogenic sedimentary structures. As a consequence , H. germanica produces a vertical transport of both mud and fine sediment fractions similarly to the sediment reworking mode reported for gallery-diffusor benthic species. This finding allows us to refine the biotur-bating mode of H. germanica, previously classified as surficial biodiffusor. Furthermore, sediment reworking intensity appeared to be dependent on the foraminiferal density. H. germanica would adapt its motion behaviour to deal with the intra-specific competition for food and space that may occur when density increases. Consequently, this behavioural modification would affect both the species and the individual contribution to sediment reworking processes. In fine, sediment reworking in H. germanica may further contribute to the bioirrigation of intertidal sediments, which has implications for oxygen availability in sediments and on aerobic microbial processes involved in carbon and nutrient cycling at the sediment-water interface.
... Shellfish meat is a product that is not resistant to long-term storage. According to Ng et al. (2013), it is explained by: the loose structure of muscle tissue, low amount of glycogen in the muscles, high water content, which serves as a favourable environment for the development of microorganisms, and the ability of snail microflora to develop at low positive temperatures (0... + 5°C). But its quality depends on storage conditions (Batyrbekov & Zhumabaev, 2017). ...
The meat of edible snails is considered a delicacy and is part of Ukraine's food exports, but there are no regulations or legislation on its quality. The purpose of this work was to develop methods for determining the degree of freshness of snail meat by the content of ammonia and ammonium salts with Nessler's reagent, peroxidase in meat with copper sulfate solution, and processing a smear-print from meat with a fluorescent dye and to determine the quality of meat by the number of green pixels. During the research, first of all, it was determined the organoleptic characteristics of shellfish meat, which reflect their freshness. Next, research was performed to determine the enzymes and ammonia that are produced during meat storage. The following reagents were used: copper sulfate solution, Nessler's reagent, and fluorescent dye – acridine orange. The equipment used for these reactions was used, namely: a KFK-2-UHL 4.2 photometer and an SMT fluorescence microscope with a working current of 2.5 A. Thus, schemes for establishing reactions for determining the degree of freshness of snail meat were developed and tested: biochemical, photometric, and immunofluorescence methods. The stability of the indicators for determining the degree of freshness was established. It is analysed that the data presented relate only to the research on snail meat. Utility model patents have been granted for each method. The proposed methods for assessing the quality of snail meat are effective, technologically simple and fast, have high reliability of the results obtained and can be used in the work of research and experimental, production and regional laboratories of veterinary medicine
... L. irrorata have the ability to detect and respond to crushed conspecifics (Duval et al., 1994), and to the chemical cues of predators present in air, water and mucus (Carroll et al., 2018;Dix & Hamilton, 1993;Duval et al., 1994). L. irrorata also possess the ability to detect cues from the mucus trails produced by conspecifics (Ng et al., 2013); therefore it is possible that they utilize them as a source of information about the presence of parasitized conspecifics. Indeed, other species of Littorina can detect trematode cercariae in the mucus trails of conspecifics and avoid associating with those infected individuals (Davies & Knowles, 2001). ...
Parasites can alter species interactions either by modifying infected host behaviour or by influencing behavioural responses in uninfected individuals. Salt marsh ecosystems are characterized by a predator–prey interaction between the keystone grazer, Littoraria irrorata, and its main predator, Callinectes sapidus, both integral players in mediating the productivity of these habitats.
Littoraria also acts as the first intermediate host for at least four species of digenetic trematode. Parasite infection has been shown to decrease grazing and climbing in populations of Littoraria, although effects on infected host response to predators have not been investigated. Moreover, how infection might increase or decrease among‐individual variation in behaviour (i.e. animal personality) is still unknown. Here we ask how trematode infection affects the expression of boldness in the anti‐predator responses of L. irrorata in both the absence and presence of a predator cue.
We find that individual boldness varies substantially, and repeatability tends to increase as the number of stressors increases, with infected individuals exposed to a predator cue showing the strongest expression of behavioural types.
Parasitism amplifies this effect, although the parasite itself does not appear to directly induce behavioural changes: infected snails show no evidence of decreased climbing or differences in refuge use as compared to their uninfected counterparts. Infection might therefore drive the expression of condition‐dependent personality differences evident only under high‐risk conditions.
Group infection status strongly influenced behavioural reaction norms: uninfected individuals grouped with an infected snail were more responsive to predation risk, exhibiting increased climbing behaviour and spending less time in the water. Here parasites are influencing personality indirectly by inducing avoidance behaviours in healthy individuals, although only in high‐risk environments.
The potential for exposure to parasites and predators fluctuates greatly across marsh ecosystems. Given the ecological importance of this predator–prey relationship, trematode infection can act as an important, although indirect, determinant of overall salt marsh community structure, health and function.
... Chemical communication is a key process in ecology that has been extensively studied over a wide range of organisms, both terrestrial and marine (Zimmer and Butman, 2000;McClintock and Baker, 2001;Dicke and Takken, 2006;Paul et al., 2006;Ng et al., 2013;Tabata, 2018). Specifically, chemical signals play a key role in intra-and inter-specific interactions (e.g. ...
The massive contamination of the environment by plastics is an increasing global scientific and societal concern. Knowing whether and how these pollutants affect the behaviour of keystone species is essential to identify environmental risks effectively. Here, we focus on the effect of plastic leachates on the behavioural response of the common blue mussel Mytilus edulis, an ecosystem engineer responsible for the creation of biogenic structures that modify the environment and provide numerous ecosystem functions and services. Specifically, we assess the effect of virgin polypropylene beads on mussels’ chemotactic (i.e. a directional movement in response to a chemical stimulus) and chemokinetic (i.e. a non-directional change in movement properties such as speed, distance travelled or turning frequency in response to a chemical stimulus) responses to different chemical cues (i.e. conspecifics, injured conspecifics and a predator, the crab Hemigrapsus sanguineus). In the presence of predator cues, individual mussels reduced both their gross distance and speed, changes interpreted here as an avoidance behaviour. When exposed to polypropylene leachates, mussels moved less compared to control conditions, regardless of the cues tested. Additionally, in presence of crab cues with plastic leachates, mussels significantly changed the direction of movement suggesting a leachate-induced loss of their negative chemotaxis response. Taken together, our results indicate that the behavioural response of M. edulis is cue-specific and that its anti-predator behaviour as well as its mobility are impaired when exposed to microplastic leachates, potentially affecting the functioning of the ecosystem that the species supports.
... However, it is premature to consider the practical use of mollusc mucus in agriculture since we have received a dual effect on seeds -negative and positive. The results are also affected by the chemical composition of the mucus, which can vary greatly from species to species and depending on environmental conditions (Skingsley et al., 2000;Ng et al., 2013). We find it interesting that there is an indirect relationship between the life cycle of the slug and the effect of mucus on seeds, and thus we suggest firstly focusing on the ecological role of mucus and then investigating practical application in agriculture, to provide reliable recommendations in the future. ...
The development of new methods of crop production is the most promising field of research in agriculture. There are numerous chemical techniques of seed treatment before sowing; however, mollusc mucus has not been considered as a natural alternative of seed treatment yet. In this study, we treated sweet pepper seeds with Spanish slug mucus before sowing. Seed germination success, germination time, as well as the performance of seedling growth were compared between experimental and control groups. The main result showed that seeds treated with slug mucus required significantly fewer days to germinate than seeds without treatment. Although treated seeds exhibited faster germination, seedlings showed slower growth than in the control group. No significant difference of seed germination success between the control and experimental group was found.
... Molluscan pedal mucus has a protective function (reviewed by Ng et al., 2013) and gel-like property (Smith, 2002), and it was possible that a proportion of larvae were trapped in the mucus, thus hindering larval entry into the snail's integument. Variation in mucus production between snail hosts could affect uptake of the larvae in other snail species, so our study findings are limited to B. lessoni only. ...
Given the importance of angiostrongyliasis as an emerging infectious disease of humans, companion animals, and wildlife, the current study focused on the transmission dynamics of first- and third-stage larvae of the parasitic nematode, Angiostrongylus cantonensis. The migration of infective larvae and their subsequent distribution within the Lymnaeidae snail, Bullastra lessoni, were investigated over time using microscopic examination of histological sections and fresh tissue. Snails were divided into four anatomical regions: (i) anterior and (ii) posterior cephalopedal masses, (iii) mantle skirt and (iv) visceral mass. The viability of free-swimming third-stage larvae, after their release from snail tissues, was evaluated in vitro by propidium iodide staining and infectivity by in vivo infection of Wistar rats. Snails were sequentially dissected over time to assess the number and anatomical distribution of larvae within each snail and hence infer their migration pathway. Herein, ongoing larval migratory activity was detected over 28 days post-infection. A comparison of infection rates and the larval distribution within the four designated snail regions demonstrated a significant relationship between anatomical region and density of infective larvae, with larvae mostly distributed in the anterior cephalopedal mass (43.6 ± 10.8%) and the mantle skirt (33.0 ± 8.8%). Propidium iodide staining showed that free-swimming third-stage larvae retained viability for between 4 and 8 weeks when stored under laboratory conditions. In contrast to viability, larval infectivity in rats remained for up to 2 weeks only. Knowledge gained from the current work could provide information on the development of new approaches to controlling the transmission of this parasite.
... Scent tracking has been postulated as an energy-saving mechanism in gastropods [45,46]. Because queen conch do not move using a slime trail, it is unclear if scent tracking is possible for the species. ...
Queen conch are among the most economically, socially, and culturally important fishery resources in the Caribbean. Despite a multitude of fisheries management measures enacted across the region, populations are depleted and failing to recover. It is believed that queen conch are highly susceptible to depensatory processes, impacting reproductive success and contributing to the lack of recovery. We developed a model of reproductive dynamics to evaluate how variations in biological factors such as population density, movement speeds, rest periods between mating events, scent tracking, visual perception of conspecifics, sexual facilitation, and barriers to movement affect reproductive success and overall reproductive output. We compared simulation results to empirical observations of mating and spawning frequencies from conch populations in the central Bahamas and Florida Keys. Our results confirm that low probability of mate finding associated with decreased population density is the primary driver behind observed breeding behavior in the field, but is insufficient to explain observed trends. Specifically, sexual facilitation coupled with differences in movement speeds and ability to perceive conspecifics may explain the observed lack of mating at low densities and differences between mating frequencies in the central Bahamas and Florida Keys, respectively. Our simulations suggest that effective management strategies for queen conch should aim to protect high-density reproductive aggregations and critical breeding habitats.
... The presence of snails on supports did not affect snail choice, which implies that the snails either were not able to detect the presence of other snails from a distance, or that the presence of snails did not constitute a stimulus. Similarly, the presence of mucus did not affect snail choices, in contrast to other species that have been shown to follow mucus trails (e.g., [16,36]). This lack of response to the mucus of snails of another species is somewhat surprising, as a recent study showed that the presence of traces of T. pisana (mucus + faeces) negatively affected the survival of C. virgata under laboratory conditions [37]. ...
Simple Summary
Terrestrial snails living in warm and dry climates had to develop strategies to survive. Several species climb on vertical supports when temperatures rise and spend the warmest months resting, typically in groups. Understanding this behavior could be useful in developing new management tools for species that are invasive. Here, we focused on four invasive snail species, and assessed their preferences for vertical supports varying in widths and heights under laboratory and field conditions. We also tested whether the presence of other snails from the same or different species affected these preferences. The snails strongly preferred wider supports in laboratory choice tests, and one species (Theba pisana) preferred taller supports as well. Results were similar in the field, where more snails were found on wider and taller supports 24 h after being released. The percentage of snails found in groups on a support was strongly density-dependent. The presence of other snails or their mucus did not affect the choices made. Overall, our results point towards the possibility of developing attractive supports to trap snails in the field.
Abstract
Terrestrial snails that live in hot and dry climates have developed strategies to cope with high summer temperatures. Several species estivate during the warmest months of the years by resting on vertical supports, typically in groups. Understanding how snails choose their estivation sites and aggregate may lead to the development of new management tools in areas where these snails are invasive. Here, we investigated the preferences of four snail species for vertical supports varying in widths and heights under laboratory and field conditions, and tested whether the presence of conspecifics or snails of other species affected these preferences. The results show that the snails strongly preferred wider supports in laboratory dual-choice tests, and one species (Theba pisana) showed a consistent preference for taller supports as well. These results were confirmed in the field, where more snails were found on wider and taller supports 24 h after being placed in test quadrats. The percentage of snails found in groups on a support was strongly density-dependent. The presence of conspecifics or their mucus did not affect the choices of the snails, nor did the presence of snails of other species or their mucus. Taken together, these results could lead to the development of attractive supports that could be used to mass-capture snails in the field.
... Periwinkles, or marine gastropod molluscs in the family Littorinidae, occur worldwide in the rocky intertidal and have been the subject of numerous evolutionary studies including many studies of sexual selection and mate choice (Ng et al. 2019;Perini et al. 2020). In the genus Echinolittorina, courtship is initiated by a male following a female's mucus trail; if this female is deemed an acceptable mate, courtship ends with the male mounting and copulating (Ng et al. 2013). Males are suspected to exhibit sizedependent mate preference because larger females likely have higher fecundity, but physically copulating with a very large female may not be possible for a smaller male or the risk of sperm competition may be very high and jeopardize paternity if multiple males target the largest females (see Ng et al. 2019). ...
A number of key processes in evolution are driven by individuals preferring mates with particular phenotypes. However, despite longstanding interest, it is difficult to quantify the strength of mate preference from phenotypic observations in nature in a way that connects directly to key parameters in theoretical models. To bridge the gap between mathematical models and empirical data, we develop a novel maximum likelihood-based method to estimate the strength and form of mate preference, where preference depends on traits expressed in both males and females. Using simulated data, we demonstrate that our method accurately infers model parameters, including the strength of mate preference and the optimal offset match between trait values in mated pairs when model assumptions are satisfied. Applying our method to two previous studies of assortative mating in marine gastropods and the European common frog, we support previous findings, but also give additional insight into the role of mate preference in each system. Our method can be generalized to a variety of plant and animal taxa that exhibit mating preferences to facilitate the testing of evolutionary hypotheses and link empirical data to theoretical models of assortative mating, sexual selection, and speciation.
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... The toe-print examination also indicates that the mucous liquid surrounding each toe pad and filling the channels is key in adhesion. In addition, the secreted mucus of gastropods, such as snails, abalones and slugs, is crucial for successful attachment and locomotion on horizontal and vertical surfaces, adjusting to humidity and salinity, self-defense, locating prey items, and mating (Grimm-Jørgensen et al., 1986;Ng et al., 2013;Pawlicki et al., 2004). However, note that there are still some challenges in both biological and artificial adhesive surfaces, which require us to re-recognize pre-existing biological adhesive surfaces in nature (Chen et al., 2019). ...
Snails offer successful attachment and locomotion on horizontal and vertical surfaces, and have inspired extensive research to develop artificial adhesives. Here, we experimentally investigate the response mechanisms of snails to mechanical signals (pull-off force and crawling angle), then propose a way to design a bioinspired sucker, and theoretically analysis its application in vacuum suction. The experimental results indicate that the pull-off force is 7 N, about 22 times of its weight, and relatively invariant across the angles of the substrate. The flexible body increases work consumption by stretching and deformation during pulling, and a cavity with negative pressure differential can exist at the interface to help resist the pulling. We extract the flexible body and formation of a negative pressure cavity at the contact interface as two key elements of the bioinspired sucker, and the analysis shows that it can be adaptable to an extend range of products compared with conventional vacuum suction, which illustrates the potential for industrial or robotic manipulation.
... Recent studies have revealed that Helix aspersa, generally known as garden snail, has two types of secretions as mucus and slime. Snail secretions have many components such as allantoin, collagen, elastin, glycolic acid, GAG, vitamins A, E and C that are convenient with human body [17,18]. Mucus is produced by the glands in the dorsal and lateral foot epithelium and shows an adhesive property whereas, slime known as 'trail' mucus, is the secretion that snails leave behind during their movement and produced by the glands located in the ventral region of the foot sole. ...
Biobased extracts comprise various bioactive components and they are widely used in tissue engineering applications to increase bioactivity as well as physical characteristics of biomaterials. Among animal sources, garden snail Helix aspersa has come into prominence with its antibacterial and regenerative extracts and show potential in tissue regeneration. Thus, in this study, bioactive Helix aspersa extracts (slime, mucus) were loaded in chitosan (CHI) matrix to fabricate porous scaffolds for hard tissue regeneration. Physical, chemical properties, antimicrobial activity was determined as well as in vitro bioactivity for bone and cartilage regeneration. Mucus and slime incorporation enhanced mechanical properties and biodegradation rate of chitosan matrix. SEM images showed that the average pore size of the scaffolds decreased with higher extract content. Mucus and slime extracts showed antimicrobial effect on two bacterial strains. In vitro cytotoxicity, osteogenic and chondrogenic activity of the scaffolds were evaluated with Saos-2 and SW1353 cell lines in terms of ALP activity, biomineralization, GAG, COMP and hydroxyproline content. Cell viability results showed that extracts had a proliferative effect on Saos-2 and SW1353 cells when compared to the control group. Mucus and slime extract loading increased osteogenic and chondrogenic activity. Thus, the bioactive extract loaded chitosan scaffolds showed potential for bone and cartilage regeneration with enhanced physical properties and in vitro bioactivity.
... Firstly, the large variation in gastropod abundance across quadrats was not entirely explained by habitat type, relative humidity, or time of day, which likely relates to intrinsic factors of gastropod populations, such as social aggregation. The strong over-dispersion detected in gastropod abundance is consistent with literature on aggregation in terrestrial gastropod molluscs (e.g., Derocerus reticulatum, [41]) which have been shown to follow each other's slime trails, for example, during homing or reproductive behavior (observed in >30 genera including the coprophilic UK snail Cepaea nemoralis [42]). Such non-environmentally forced clustering is likely to explain the non-uniform distribution of gastropods across dog-walking areas, even when habitat types and levels of humidity were suitable for gastropod activity. ...
Simple Summary
Angiostrongylus vasorum is a serious parasitic disease increasing in range and prevalence in Europe. The parasite passes through land slugs and snails before it can infect dogs but contact between dogs and these intermediate hosts is not well studied. We surveyed dogs and slugs/snails in parks and on streets in an urban A. vasorum hotspot area in southern England, United Kingdom, with the aim of determining the conditions under which they overlap. We counted 1672 slugs/snails and 763 dogs across seven sites. We found that habitat types in which the hosts were present differed, with dogs occurring 15× more often on hard surfaces (e.g., concrete) than woodland/scrub, but also occurring on natural grassland. Large numbers of slugs/snails were present 5.82× more often in woodland/scrub and natural grassland than on hard surfaces. Slug and snail species at risk of a greater likelihood of infection with A. vasorum were present 65.12× more often in woodland/scrub and 62.17× more often in amenity grassland than other habitats. The results suggest that contact between dogs and slugs/snails is most likely in amenity and natural grassland but that infection risk with A. vasorum is greatest in amenity grassland and woodland/scrub.
Abstract
Angiostrongylusvasorum is a helminth parasite of domestic dogs that is increasing in range and prevalence. Its lifecycle requires terrestrial gastropod mollusc (“gastropod”) intermediate hosts, but research is lacking regarding contact risk in situ. We studied co-occurrence between dogs and gastropods in dog-walking spaces in an A. vasorum hotspot in southern England, United Kingdom, with the aim of quantifying environmental and spatio-temporal overlap. We surveyed 390 quadrats and 180 point-counts along 3 km transects at seven sites, yielding 1672 gastropod and 763 dog observations. Common gastropods comprised Arion, Cornu, Monacha, Deroceras, Tandonia, Cochlicella, and Trochulus species. Habitat was the most important factor structuring both gastropod and dog presence and abundance. Likelihood ratio comparisons from conditional probability trees revealed that dogs were 15× more likely to be present on hardstanding surfaces than other habitats but were also present on natural and amenity grassland. Presence of gastropod species associated with high A. vasorum prevalence was 65.12× more likely in woodland/scrub and 62.17× more likely in amenity grassland than other habitats. For gastropods overall, high abundance was 5.82× more likely in woodland/scrub and natural grassland. The findings suggest co-occurrence is highest in amenity and natural grassland, but infection risk is greatest in amenity grassland and woodland/scrub.
... Microhabitats like cracks and crevices on tidal flat were preferred for shelter during storm surge or tidal wave shock (Saier, 2000;Carlson et al., 2006). Trail following behaviour in gastropods help them to locate prey and attached food particles on previously laid mucus trail (Ng et al., 2013). ...
The phylum mollusca, the second largest non chordate group of organisms inhabits all types of terrestrial and aquatic habitats. Benthic invertebrates represent an important group in the mangrove food web; influence various functional aspects in the ecosystem like energy flows, nutrient re-mineralization in the sediment etc. In this article, strong relationship between various environmental factors on molluscs in estuarine habitats is discussed. Analysis have been made on the influential environmental variance such as temperature, light, pH, tidal cycle, salinity, soil substratum, humidity and other environmental attributes on the behavioural response and external structure of molluscs.
... Indeed, copulating L. compressa individuals were significantly smaller than those of L. saxatilis and L. arcana (Fig. 4). The snails following the trail of a prospective mate 92 can perceive chemical and mechanical cues, including the size of the snail that left the trail 45,93 . Pronounced differences in the size and the shape of the shell between the wave and the crab ecotypes of L. saxatilis are supposed to drive strong assortative mating 31,50,[94][95][96] . ...
Sympatric coexistence of recently diverged species raises the question of barriers restricting the gene flow between them. Reproductive isolation may be implemented at several levels, and the weakening of some, e.g. premating, barriers may require the strengthening of the others, e.g. postcopulatory ones. We analysed mating patterns and shell size of mates in recently diverged closely related species of the subgenus Littorina Neritrema (Littorinidae, Caenogastropoda) in order to assess the role of premating reproductive barriers between them. We compared mating frequencies observed in the wild with those expected based on relative densities using partial canonical correspondence analysis. We introduced the fidelity index (FI) to estimate the relative accuracy of mating with conspecific females and precopulatory isolation index (IPC) to characterize the strength of premating barriers. The species under study, with the exception of L. arcana, clearly demonstrated preferential mating with conspecifics. According to FI and IPC, L. fabalis and L. compressa appeared reliably isolated from their closest relatives within Neritrema. Individuals of these two species tend to be smaller than those of the others, highlighting the importance of shell size changes in gastropod species divergence. L. arcana males were often found in pairs with L. saxatilis females, and no interspecific size differences were revealed in this sibling species pair. We discuss the lack of discriminative mate choice in the sympatric populations of L. arcana and L. saxatilis, and possible additional mechanisms restricting gene flow between them.
Synopsis
Social predation is a common strategy used by predators to subdue and consume prey. Animals that use this strategy have diverse methods of finding each other, organizing behaviors, and capturing prey. There is wide variation in the extent to which these behaviors are coordinated and in the stability of individual roles. This study characterizes social predation by the nudibranch mollusc, Berghia stephanieae, which is a specialist predator that eats only the sea anemone, Exaiptasia diaphana. A combination of experimental and modeling approaches established that Berghia consistently preys upon E. diaphana in groups, even when resources are abundant. However, this preference for social foraging does not appear to be a fixed personality trait, as individuals did not exhibit stable roles such as leader or follower. Instead, the population exhibited fission–fusion dynamics with temporary roles during predation. The extent of this social feeding was not altered by length of food deprivation, suggesting that animals are not shifting strategies based on hunger state. Furthermore, classic gastropod cues—such as slime trails, attraction to injured anemones, or preference for conspecifics feeding—did not facilitate group formation. Thus, Berghia provides an example of a specialist predator of dangerous prey that loosely organizes social feeding, independent of hunger state and fixed individual roles, while the mechanism of aggregation remains unknown.
Significance Statement
Social predation is an adaptive strategy that enables predators to subdue dangerous prey while minimizing injury. Many nudibranchs specialize to predate upon cnidarians, which pose unique challenges due to their potent defenses. Although nudibranchs are often characterized as solitary hunters, our study reveals that Berghia stephanieae exhibits social predation behaviors, forming temporary, fluid groups to feed on sea anemones. These groups lack stable social structures, with individuals adopting temporary roles such as joining or initiating feeding. Interestingly, we found no evidence that aggregation is driven by simple cues such as slime trails, conspecific activity, or prey injury, suggesting that group formation may depend on more complex or context-specific mechanisms. This work highlights the need for further research into the ecological and sensory factors underlying social predation in nudibranchs and other marine predators.
In this paper, a novel Snail Homing and Mating Search (SHMS) algorithm is proposed. It is inspired from the biological behaviour of the snails. Snails continuously travels to find food and a mate, leaving behind a trail of mucus that serves as a guide for their return. Snails tend to navigate by following the available trails on the ground and responding to cues from nearby shelter homes. The proposed SHMS algorithm is investigated by solving several unimodal and multimodal functions. The solutions are validated using standard statistical tests such as two-sided and pairwise signed rank Wilcoxon test and Friedman rank test. The solution obtained from the SHMS algorithm exhibited superior robustness as well as search space exploration capabilities within the less computational cost. The real-world application of SHMS algorithm is successfully demonstrated in the engineering design domain by solving three cases of design and economic optimization shell and tube heat exchanger problem. The objective function value and other statistical results obtained using SHMS algorithm are compared with other well-known metaheuristic algorithms.
The coastal fishing of the snail Titanostrombus galeatus is carried out in some coastal countries of the Tropical Eastern Pacific. In this study, the individual growth of T. galeatus that are fished in the community at Punta Maldonado was estimated. The size structure was made using the shell length (SL), and the growth parameters were estimated through the five Schnute cases, where cases 1, 2, and 5 describe asymptotic growth and cases 3 and 4 describe nonasymptotic growth. The male population was more abundant than the females, with 398 and 322 specimens, respectively, but the females were larger (198 ± 9.66 mm). In general, the average SL during the two sampling cycles was 196 ± 9.44 mm; this size was not significantly different between the first and second cycles (P = 0.98). Females had a greater range of SL (170–267 mm) compared with males (170–240 mm). The lengths of both sexes showed significant differences between months (P < 0.05). The multinomial analysis showed a multimodal SL distribution, with one to three modal groups for females and males. In growth, cases 2 and 5 were the ones that best describe the growth in females, in males the best were cases 5 and 2. According to the best case (case 2) in females, the growth curve is sigmoidal. In males, the best case (case 5) describes growth according to an inverted exponential curve. In relation to the estimated growth parameters, females showed faster growth than males, analyzed using Kimura's test. The present investigation is the first that reports the growth for both sexes of T. galeatus using the five cases of the Schnute model. The information generated can be used for management purposes, as this species is not currently regulated in Mexico.
Mucus-mediated communication plays a significant role in shaping community dynamics, particularly in marine organisms found in intertidal zones with complex topography. In this study, we investigated the host preference of a flatworm Stylochoplana pusilla, which lives symbiotically with intertidal gastropods, and its responses to the host and conspecific mucus. Our line transect surveys revealed differences in flatworm prevalence among sympatric gastropods, with multiple flatworms found in a single host individual, indicating host preference. The body mucus of gastropods and flatworms was applied to one side of a Petri dish to experimentally determine whether flatworms prefer the mucus-coated side under light and dark conditions. However, contrary to our expectations, the experiments in both light and dark conditions showed that the mucus of none of the host gastropods effectively attracted flatworms, suggesting that mucus-mediated communication may not be the primary factor in establishing host preference, and other ecological factors may play a role. Nonetheless, under dark conditions, flatworms were attracted to conspecific mucus, indicating that they may engage in collective homing behaviour or conspecific aggregation to find a suitable position in the mantle cavity. Overall, our results highlight the complex ecological interactions involved in shaping symbiosis between flatworms and gastropods.
Predator–prey interactions structure ecological communities, and personality can significantly mediate these interactions. Personality expression is often contingent on social context, suggesting that group personality may be key in determining the outcomes of predator encounters. Here, we test the influence of individual personality and group composition on survival of the marsh periwinkle, Littoraria irrorata, when exposed to its main predator, the blue crab, Callinectes sapidus, both integral players in mediating the productivity and health of salt marsh ecosystems. Snails were categorized as having bold or shy personality types, which were unrelated to shell length, though neither trait influenced survival when individual snails were exposed to a predator. However, when snails were partitioned into groups differing in personality composition, snails in groups with bold individuals had higher survival than those in groups with none. While group type did not influence the survival of bold snails, shy snails performed better in mixed groups: the presence of a few bold individuals emerged as especially effective in decreasing mortality of shy snails. The effect of personality on predator escape is thus conditional on group personality composition, indicating that social context can directly impact the survival and success of its individual members, with broad implications for community dynamics.
Transmission between hosts is crucial to the growth, development and reproduction of many parasites. As a consequence, parasites are under selection to maximise transmission success and exhibit many behavioural and morphological adaptations that allow detection of, and movement between, hosts. However, transmission success is not determined by parasites alone, but is also shaped by host behaviours. Often, host behaviours function to minimise the risk of exposure to parasites; in some cases, however, host behaviours may be manipulated by parasites to increase transmission success. In this study, we investigated transmission of the parasitic mite Riccardoella oudemansi between slug (Limacus maculatus) hosts, considering the role of both host and parasite behaviour in determining transmission success. Host-host transmission occurred when slugs were in physical contact, but mites were also capable of moving across the substrate to locate new hosts, a process facilitated by mucus trails. We found no strong evidence that slugs avoid parasitised conspecifics, or that mites manipulate slug behaviour to increase transmission. Finally, mites showed a preference for the mucus of parasitised slugs, but did not discriminate between mucus from their own host and another parasitised slug. A general preference for mucus from parasitised slugs is likely to be important in encouraging mites to remain in close contact with their host and may also facilitate host-switching and outbreeding. We encourage further study of parasitism by Riccardoella in limacid slugs, where cross-species variation in host social behaviour may drive differences in the rate and success of parasite transmission across slug species.
Many gastropods release mucus hydrogels, which help them to remain attached to different substrates. Although not as strong as synthetic or biomimetic adhesives, some of these hydrogels have the ability to adhere to wet surfaces. These complex hydrogels mainly consist of proteins and carbohydrates, their natural cross-linking reactions being dependent on the presence of metals. In this paper, we investigated the role of metals in improving the underwater adhesive property of the mucus hydrogel from the slug Laevicaulis alte. We found that the strength and duration of attachment of two glass surfaces under water by the mucus hydrogel could be enhanced by its simple treatment with salts of metals, namely, Ca, Mg, Cu, or Zn. The degree of enhancement followed the order Ca²⁺ < Mg²⁺ < Zn²⁺ < Cu²⁺. The Cu²⁺-treated hydrogel kept two glass surfaces attached under water for about 20 days, while Zn²⁺ treatment caused attachment for about 15 days, as compared to the 3–5 days of attachment caused by the untreated gel. Treatment with both metals increased the underwater stability of the hydrogel almost threefold, presumably by strengthening its cross-linking. However, the Cu²⁺-treated hydrogel fell short of its adhesive function in the case of fast attachment within time scale of minutes, showing considerably low adhesive strength. From this study, we conclude that the treatment with Zn²⁺ is the best choice for improvement of the underwater adhesive property in terms of strength and stability. Overall, this work presents a novel biological underwater adhesive. The dynamic behavior of this multicomponent hydrogel in a versatile metal-rich environment may guide us toward designing new useful biomimetics.
The Common or Brown Garden Snail, Cornu aspersum, is an invasive land snail that has successfully colonized a diverse range of global environments. Like other invasive land snails, it is a significant pest of a variety of agricultural crops, including citrus, grapes and canola. Cornu aspersum secretes a mucus trail when mobile that facilitates locomotion. The involvement of the trail in conspecific chemical communication has also been postulated. Our study found that anterior tentacle contact with conspecific mucus elicited a significant increase in heart rate from 46.9 to 51 beats per minute. In order to gain a better understanding of the constituents of the trail mucus and the role it may play in snail communication, the protein and volatile components of mucus trails were investigated. Using two different protein extraction methods, mass spectrometry analysis yielded 175 different proteins, 29 of which had no significant similarity to any entries in the non-redundant protein sequence database. Of the mucus proteins, 22 contain features consistent with secreted proteins, including a perlucin-like protein. The eight most abundant volatiles detected using gas chromatography were recorded (including propanoic acid and limonene) and their potential role as putative pheromones are discussed. In summary, this study has provided an avenue for further research pertaining to the role of trail mucus in snail communication and provides a useful repository for land snail trail mucus components. This may be utilized for further research regarding snail attraction and dispersal, which may be applied in the fields of agriculture, ecology and human health.
Pharmaceutical drugs are among the most used chemicals for human and veterinary medicines, aquaculture and agriculture. Pharmaceuticals are environmentally persistent, biologically active molecules, thereby having the potential to exert biological effects on non-target species. Among the most used pharmaceuticals, one may find salicylic acid (SA), a non-steroid anti-inflammatory drug (NSAID) that acts by inhibiting the enzymes cyclooxigenases; it is also possible to identify acetazolamide (ACZ), a diuretic that acts by inhibiting the activity of carbonic anhydrase (CA). In this work, the effects of both single and combined effects of these drugs were assessed on the marine gastropod Phorcus lineatus, by measuring key enzymatic activities, namely carbonic anhydrase (CA) and cyclooxygenase (COX), under two different exposure periods (14 and 28 days). We observed no straightforward pattern of enzymatic response in all treatments of both pharmaceuticals, on both analyzed tissues (gut and gills), and for both exposure regimes. We assume that this species is not responsive to the hereby tested pharmaceuticals, a finding that may be due to general mechanisms of response to adverse conditions, such as reduction of metabolism, of heart rate, of filtration rates, and to the increase production of mucus. All these functional adaptations can mitigate the deleterious effects caused by adverse conditions, without triggering biochemical responses. In conclusion, the species P. lineatus seems not to be sensitive in terms of these specific enzymatic pathways to these contaminants, under the adopted conditions.
Self-organization was introduced originally in the context of physics and chemistry to describe how microscopic processes give rise to macroscopic stuctures in out-of-equilibrium systems, Recent research that extends this concept to ethology suggests that it provides a concise description of a wide range of collective phenomena in animals, especially in social insects. This description does not rely on individual complexity to account for complex spatiotemporal features that emerge at the colony level, but rather assumes that intractions among simple individuals can produce highly structured collective behaviours.
(1) Various mechanisms have been evolved to reduce intraspecific competition in South African Patella spp. On the basis of these, two groups can be distinguished, `migratory' and `non-migratory'. (2) Migratory species settle low on the shore and migrate progressively upwards, thus occupying a wider range; P. granularis, P. granatina, P. concolor and P. oculus comprise the group. Upwards migration occurs mainly in winter and short-term returns may occur in summer. In conjunction with migration, these species are generalized browsers, non-aggressive to their own species and have a random to aggregated distribution. Aggregations occur under desiccating conditions. Scars are often poorly defined or temporary and homing is variable and usually not well developed (except under desiccation). Territorial behaviour is lacking and there is no marked adult-juvenile differentiation with respect to habitat or food. (3) The `non-migratory' group includes species which settle in a narrow zone and remain there throughout life. P. cochlear, P. longicosta, P. tabularis, P. miniata, P. argenvillei and P. compressa conform to this. P. compressa lives only on the kelp Ecklonia maxima. In these species, specialized mechanisms have been evolved to reduce competition. Food requirements are often specific. The limpets respond aggressively to like species, and are therefore dispersed. Many show territorial behaviour and form permanent scars within their territories. Homing is rigid. In some species the foodplant is established, maintained and defended by the limpet. There is a differentiation of habitat or food between adults and juveniles. (4) The relative development of migratory or non-migratory tendencies is graded and most intense in high density species. Patella barbara (with the lowest density) is the only obvious intermediate form.
Infrared (IR) spectroscopy was used to study pedal mucous characteristics of eight species of marine gastropods to determine if it was useful for species identification. Three species of Nerita, two morphologically indistinguishable species of Littoraria (L. articulata and L. strigata) and one species each of Nodilittorina, Austrolittorina and Echinolittorina, were compared with a terrestrial snail, Achatina fulica. The IR spectra all showed high absorption in the 900–2100 cm!1 wave number region. No benzene overtones were observed at low wave numbers (1800–2000 cm!1) suggesting that aromatic amino acids could be lacking
in core glycoprotein molecules. Strong absorption bands at peaks of 1644 cm!1 and 1545 cm!1 were obtained for all species and attributable to amide-I and amide-II peaks respectively. Amide I (range 1600–1720 cm !1) to Amide II (1500–1600 cm!1) band area ratios ranged significantly: Nerita species: 1: 0.10–1: 0.22; Achatina fulica 1: 0.40; and Littoraria sp. 1: 0.48; Austrolittorina unifastciata: 1: 0.57; Echinolittorina malaccana: 1: 0.65 and Nodilittorina pyramidalis: 1: 0.74. These differences appear useful for distinguishing
between the six genera and congeneric species studied.
Stuart Kauffman here presents a brilliant new paradigm for evolutionary biology, one that extends the basic concepts of Darwinian evolution to accommodate recent findings and perspectives from the fields of biology, physics, chemistry and mathematics. The book drives to the heart of the exciting debate on the origins of life and maintenance of order in complex biological systems. It focuses on the concept of self-organization: the spontaneous emergence of order widely observed throughout nature. Kauffman here argues that self-organization plays an important role in the emergence of life itself and may play as fundamental a role in shaping life's subsequent evolution as does the Darwinian process of natural selection. Yet until now no systematic effort has been made to incorporate the concept of self-organization into evolutionary theory. The construction requirements which permit complex systems to adapt remain poorly understood, as is the extent to which selection itself can yield systems able to adapt more successfully. This book explores these themes. It shows how complex systems, contrary to expectations, can spontaneously exhibit stunning degrees of order, and how this order, in turn, is essential for understanding the emergence and development of life on Earth. Topics include the new biotechnology of applied molecular evolution, with its important implications for developing new drugs and vaccines; the balance between order and chaos observed in many naturally occurring systems; new insights concerning the predictive power of statistical mechanics in biology; and other major issues. Indeed, the approaches investigated here may prove to be the new center around which biological science itself will evolve. The work is written for all those interested in the cutting edge of research in the life sciences.
The study of speciation in recent populations is essentially a study of the evolution of reproductive isolation mechanisms between sub-groups of a species. Prezygotic isolation can be of central importance to models of speciation, either being a consequence of reinforcement of assortative mating in hybrid zones, or a pleiotropic effect of morphological or behavioral adaptation to different environments. To suggest speciation by reinforcement between incipient species one must at least know that gene flow occurs, or have recently occurred, and that assortative mating has been established in the hybrid zone. In Galician populations of the marine snail Littorina saxatilis, two main morphs appear on the same shores, one on the upper-shore barnacle belt and the other in the lower-shore mussel belt. The two morphs overlap in distribution in the midshore where hybrids are found together with pure forms. Allozyme variation indicates that the two parental morphs share a common gene pool, although within shores, gene flow between morphs is less than gene flow within morphs. In this study, we observed mating behavior in the field, and we found that mating was not random in midshore sites, with a deficiency of heterotypic pairs. Habitat selection, assortative mating, and possibly sexual selection among females contributed to the partial reproductive isolation between the pure morphs. Sizes of mates were often positively correlated, in particular, in the upper shore, indicating size-assortative mating too. However, this seemed to be a consequence of nonrandom microdistributions of snails of different sizes. Because we also argue that the hybrid zone is of primary rather than secondary origin, this seems to be an example of sympatric reproductive isolation, either established by means of reinforcement or as a by-product to divergent selection acting on other characters.
Comparison of the behaviour of slugs before and during trail following shows that there is no change in their rates of locomotion but that there are decreases in measures of tentacle activity (distance moved and the frequency of substrate contacts) during trail following. Bilateral amputation of tentacles has the general effect of slowing the speed of locomotion whether trail following or not, and preventing the decrease in tentacle activity during trail following.
Amputation of the anterior tentacles results in a decrease in the accuracy with which trails are followed. Amputation of the posterior tentacles on the other hand, results in a decrease in the frequency with which slugs turned onto trails. Removal of all the tentacles prevents trail following. It is concluded that the posterior tentacles are concerned with the detection and identification of trails which are subsequently followed and that the anterior tentacles normally control the behaviour of the slug on the trail.
Despite their different organization and biology, chitons (Mollusca, Polyplacophora) and gastropods (Mollusca, Gastropoda) share a large number of adaptations to intertidal life, including morpho-functional and behavioural traits. Communication, clustering, aggressiveness and even simple parental cares have been reported in both classes but, as in other animals, the basis of their behavioural adaptation to the intertidal environment is a proper organization of activity in space and time.
A revised six-kingdom system of life is presented, down to the level of infraphylum. As in my 1983 system Bacteria are treated as a single kingdom, and eukaryotes are divided into only five kingdoms: Protozoa, Animalia, Fungi, Plantae and Chromista. Intermediate high level categories (superkingdom, subkingdom, branch, infrakingdom, superphylum, subphylum and infraphylum) are extensively used to avoid splitting organisms into an excessive number of kingdoms and phyla (60 only being recognized). The two 'zoological' kingdoms, Protozoa and Animalia, are subject to the International Code of Zoological Nomenclature, the kingdom Bacteria to the International Code of Bacteriological Nomenclature, and the three 'botanical' kingdoms (Plantae, Fungi, Chromista) to the International Code of Botanical Nomenclature. Circumscriptions of the kingdoms Bacteria and Plantae remain unchanged since Cavalier-Smith (1981). The kingdom Fungi is expanded by adding Microsporidia, because of protein sequence evidence that these amitochondrial intracellular parasites are related to conventional Fungi, not Protozoa. Fungi are subdivided into four phyla and 20 classes; fungal classification at the rank of subclass and above is comprehensively revised. The kingdoms Protozoa and Animalia are modified in the light of molecular phylogenetic evidence that Myxozoa are actually Animalia, not Protozoa, and that mesozoans are related to bilaterian animals. Animalia are divided into four subkingdoms: Radiata (phyla Porifera, Cnidaria, Placozoa, Ctenophora), Myxozoa, Mesozoa and Bilateria (bilateral animals: all other phyla). Several new higher level groupings are made in the animal kingdom including three new phyla: Acanthognatha (rotifers, acanthocephalans, gastrotrichs, gnathostomulids), Brachiozoa (brachiopods and phoronids) and Lobopoda (onychophorans and tardigrades), so only 23 animal phyla are recognized. Archezoa, here restricted to the phyla Metamonada and Trichozoa, are treated as a subkingdom within Protozoa, as in my 1983 six-kingdom system, not as a separate kingdom. The recently revised phylum Rhizopoda is modified further by adding more flagellates and removing some 'rhizopods' and is therefore renamed Cercozoa. The number of protozoan phyla is reduced by grouping Mycetozoa and Archamoebae (both now infraphyla) as a new subphylum Conosa within the phylum Amoebozoa alongside the subphylum Lobosa, which now includes both the traditional aerobic lobosean amoebae and Multicilia. Haplosporidia and the (formerly microsporidian) metchnikovellids are now both placed within the phylum Sporozoa. These changes make a total of only 13 currently recognized protozoan phyla, which are grouped into two subkingdoms: Archezoa and Neozoa; the latter is modified in circumscription by adding the Discicristata, a new infrakingdom comprising the phyla Percolozoa and Euglenozoa). These changes are discussed in relation to the principles of megasystematics, here defined as systematics that concentrates on the higher levels of classes, phyla, and kingdoms. These principles also make it desirable to rank Archaebacteria as an infrakingdom of the kingdom Bacteria, not as a separate kingdom. Archaebacteria are grouped with the infrakingdom Posibacteria to form a new subkingdom, Unibacteria, comprising all bacteria bounded by a single membrane. The bacterial subkingdom Negibacteria, with separate cytoplasmic and outer membranes, is subdivided into two infrakingdoms: Lipobacteria, which lack lipopolysaccharide and have only phospholipids in the outer membrane, and Glycobacteria, with lipopolysaccharides in the outer leaflet of the outer membrane and phospholipids in its inner leaflet. This primary grouping of the 10 bacterial phyla into subkingdoms is based on the number of cell-envelope membranes, whilst their subdivision into infrakingdoms emphasises their membrane chemistry; definition of the negibacterial phyla, five at least partly photosynthetic, relies chiefly on photosynthetic mechanism and cell-envelope structure and chemistry corroborated by ribosomal RNA phylogeny. The kingdoms Protozoa and Chromista are slightly changed in circumscription by transferring subphylum Opalinata (classes Opalinea, Proteromonadea, Blastocystea cl. nov.) from Protozoa into infrakingdom Heterokonta of the kingdom Chromista. Opalinata are grouped with the subphylum Pseudofungi and the zooflagellate Developayella elegans (in a new subphylum Bigyromonada) to form a new botanical phylum (Bigyra) of heterotrophs with a double ciliary transitional helix, making it necessary to abandon the phylum name Opalozoa, which formerly included Opalinata. The loss of ciliary retronemes in Opalinata is attributed to their evolution of gut commensalism. The nature of the ancestral chromist is discussed in the light of recent phylogenetic evidence.
Excursions of Limax pseudoflavus (Evans) were recorded over 9 days using time lapse cinematography. Excursions were made at night, ending before sunrise, and were significantly more frequent in wet than in dry weather. The homes of these slugs are species rather than population or individual specific. Animals tended to home upwind but the direction in which they left home was not significantly correlated with wind direction. Trail following may be involved in homing. All but one example of homing may be interpreted in terms of distant chemoreception, rheotaxis and trail following. Using these mechanisms alone a slug's best strategy for feeding and homing is discussed.
Clustering behavior of the gastropod Planaxis sulcatus was investigated seasonally and in different shore levels on the Suez Canal rocky shores. The numbers of clusters/m2 and individual abundance/cluster in hot summer were significantly greater than in winter particularly in high and midshores. Clusters were more frequent in crevices than over boulders. There is a decline in snail size in summer due to the appearance of new recruits. Results of movement experiments revealed that the spreading of snails is faster in winter than in summer which showed high mortalities.
Prairie rattlesnakes rapidly formed chemical search images of natural prey. With the snake behind a barrier, chemical trails were made with two deer mice. Then the snake struck one of these mice and was allowed to choose between the two trails, with neither mouse present. The trail previously made by the mouse that was eventually struck was selected on 83.3% of the trials. -from Authors
This book presents a synthesis of current knowledge and research on the biology of terrestrial gastropod molluscs, which are of importance to human societies as food, medicine, crop pests, vectors of parasites, and as tools, personal ornamentation and currency in trade. It covers the morphology, phylogeny and systematics, structure and function of the various organ systems, feeding behaviour, life history strategies, behavioural ecology, population and conservation genetics, and soil biology and ecotoxicology of the terrestrial molluscs.
Focuses on features of dog-whelk biology that are amenable to field study - feeding, predation, breeding, response to environmental stimuli and variation in shell characters. -from Author
The structure and dynamics of biological communities cannot be understood without considerable background information about the ecology of the component species. Experimental manipulations of natural populations in field situations are often the most profitable method of determining the factors that affect the distribution and abundance of species. Intertidal organisms have proved to be suitable for such direct experimentation because of the ease of access to intertidal areas, the relatively sessile nature, and due to the great abundance of many of the organisms. The chapter elaborates the key observations made on the ecology of intertidal gastropods such as the factors affecting their establishment of distributional patterns and the maintenance of distributional patterns caused through their behavioral adaptations and physiological stress. It dwells on the competition and predation due to the distribution and abundance of population of intertidal gastropods, its reproductive biology, and the geographical distribution and influences of gastropods on the structure of intertidal communities. The chapter also lists the observations based on general hypotheses and highlights the gap in the knowledge on ecology and behavior of intertidal gastropods, thus, paving a foundation for future research and investigations.
Pedal and hypobranchial mucus production of the common whelk Buccinum undatum L. were measured at three different temperatures (8.2, 10.5 and 15-degrees-C). Pedal mucus production at 8.2-degrees-C was significantly lower from that at 10.5-degrees-C, but similar to that at 15-degrees-C. In contrast hypobranchial mucus production at 8.2-degrees-C was significantly higher than that at 10.5-degrees-C but again similar to that at 15-degrees-C. At all temperatures whelks produced more hypobranchial than pedal mucus. Food consumption was measured, and from this it was determined that almost-equal-to 27.5% of the total energy intake appeared as mucus production (pedal + hypobranchial). Other studies on gastropod mucus energetics are reviewed, and possible sources of error in the determination of mucus energetics are discussed.
Euglandina feeds on other gastropods either by quickly sucking the contents from the shell, or by swallowing the prey whole, which can
be more time consuming. When Euglandina were offered prey species of various sizes, they preferentially consumed the smaller individuals, and often swallowed these
whole. Handling time increased with decreasing density since swallowing prey whole became more frequent at the lower densities.
The relationship between prey size, predator size, handling time and feeding technique was examined. For the two feeding techniques
observed, handling time increased exponentially with the size of the prey and decreased exponentially with the size of the
predator. Predators of intermediate size tended to swallow prey whole more frequently than did the smallest and largest.
These data are interpreted in terms of the animal behaving in such a way as to balance its rate of intake of both organic
matter, which resides mainly in the soft parts, and of calcium, which resides mainly in the shell.
Species occupying different ecological niches may evolve ecotypes that differ in size as a result of divergent selection on this trait. Size differences may affect mate preference and cause deviations from random mating. Several marine snails of the genus Littorina have ecotypes that differ in size and earlier studies have shown strong assortative mating between differently sized ecotypes in at least one of these species, L. saxatilis. Here we studied male mate choice in two ecotypes of the congeneric L. fabalis that differ in size. We found mating to be nonrandom, because males of the large ecotype followed the mucus trails and copulated with females of their own large ecotype more than with females of the smaller ecotype. Males of the smaller ecotype showed no strong preference, but tended to copulate more with females of the large ecotype than with their own females. Further experiments using the small ecotype showed that mate choice was size-based, with a general preference of the males to mate large females. It seems likely that the partial reproductive barrier that we describe somewhat impedes gene flow between the two ecotypes of L. fabalis, a result that corroborates earlier observations of a weak, but significant, gene-flow barrier across zones where the two ecotypes overlap and hybridize.
The study of speciation in recent populations is essentially a study of the evolution of reproductive isolation mechanisms between sub-groups of a species. Prezygotic isolation can be of central importance to models of speciation, either being a consequence of reinforcement of assortative mating in hybrid zones, or a pleiotropic effect of morphological or behavioral adaptation to different environments. To suggest speciation by reinforcement between incipient species one must at least know that gene flow occurs, or have recently occurred, and that assortative mating has been established in the hybrid zone. In Galician populations of the marine snail Littorina saxatilis, two main morphs appear on the same shores, one on the upper-shore barnacle belt and the other in the lower-shore mussel belt. The two morphs overlap in distribution in the midshore where hybrids are found together with pure forms. Allozyme variation indicates that the two parental morphs share a common gene pool, although within shores, gene flow between morphs is less than gene flow within morphs. In this study, we observed mating behavior in the field, and we found that mating was not random in midshore sites, with a deficiency of heterotypic pairs. Habitat selection, assortative mating, and possibly sexual selection among females contributed to the partial reproductive isolation between the pure morphs. Sizes of mates were often positively correlated, in particular, in the upper shore, indicating size-assortative mating too. However, this seemed to be a consequence of nonrandom microdistributions of snails of different sizes. Because we also argue that the hybrid zone is of primary rather than secondary origin, this seems to be an example of sympatric reproductive isolation, either established by means of reinforcement or as a by-product to divergent selection acting on other characters.
Activity patterns, microhabitat occurrences, and behaviors during low tides of 10 common gastropods inhabiting rocky intertidal shores of the Pacific coast of Panama were examined. During daytime low tides, most snails occurred in crevices, on vertical surfaces, or in tidepools. Daytime physical stress at a given tidal level increased along the microhabitat gradient: crevices<tidepools<vertical surfaces<slopes<horizontal surfaces. In addition to the above mechanisms, 6 gastropods showed specific behaviors during sunny low tides that apparently further ameliorated stress. For predatory gastropods, one herbivorous snail, and two limpets, microhabitat was of vital importance in reducing stress, but several snails and a limpet had additional behavioral or morphological adaptations that further lessened stress and allowed them to persist over a wider range of microhabitats. A neritid formed multilayered aggregations, lost extravisceral water at a controlled rate, and reduced tissue temperature by evaporative cooling: 2 littorinids used mucus to attach and orient shells to lessen heat gain as well as to reduce water loss; and at least one pulmonate limpet maintained a raised posture on its home scar to lessen contact with substrate and allow evaporative cooling.-from Author
The power of locomotion of a terrestrial slug rises linearly with crawling speed. The metabolic cost of movement is 904 joules per kilogram per meter, considerably more than that reported for other forms of locomotion. This high cost is primarily attributable to the production of the pedal mucus by which the slug adheres to the substratum.
The pedal mucus of gastropods functions in locomotion by coupling the movements of the foot to the substratum. The pedal mucus of the terrestrial slug, Ariolimax columbianus, is suited to this role by the following unusual physical properties.
At small deformations the mucus is a viscoelastic solid with a shear modulus of 100–300 Pa. The mucus shows a sharp yield point at a strain of 5–6, the yield stress increasing with increasing strain rate. At strains greater than 6 the mucus is a viscous liquid (η = 30–50 poise). The mucus recovers its solidity if allowed to ‘heal’ for a period of time, the amount of solidity recovered increasing with increasing time.
Using field and laboratory experiments, this study evaluated whether the pedal mucus of several rocky intertidal species of gastropods from central Chile retained and allowed germination of seaweed propagules. Field-exposed slides coated with mucus retained significantly greater numbers of propagules than uncoated slides, suggesting that the mucus may contribute to propagule attachment in the field. The importance of such an effect, however, would vary with immersion time of the habitat considered, the type of gastropod and the kind of seaweed involved. Comparisons between propagule abundance on uncoated and coated slides indicated that the latter could be used as a spore trapper to document rapid changes of spore abundance in the water column. In addition, coated slides retained free floating, seemingly detached, developmental stages of various kinds of seaweeds that never appeared in the uncoated slides used as controls.