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Do Predator Cues Influence Turn Alternation Behavior in Terrestrial Isopods Porcellio laevis Latreille and Armadillidium vulgare Latreille?
... This behavior has been observed and studied in a wide range of animals, particularly terrestrial isopods (Grosslight and Ticknor 1953;Aderman and Dawson 1970;Hughes 1973Hughes , 1987Ramey et al. 2009;Izumi et al. 2013;Bögli and Huang 2017;Lewis et al. 2017;Nakashima et al. 2018;Rothacher et al. 2020). For example, woodlice frequently use TA to flee from adverse or potentially harmful conditions, such as food deprivation (Hughes 1978), excessive disturbance at the substrate level (Houghtaling and Kight 2006), indirect signals from predators (Hegarty and Kight 2014), exposure to predators (Hughes 1967(Hughes , 1978Carbines et al. 1992), excessive light or drought stress (Hughes 1967), and artificial stimulation (Ono and Takagi 2006). TA is condition-dependent and occurs when its benefits are greater than that of a random turn. ...
... TA frequency, or the number of TAs, has been investigated using a maze device with triple T-junctions and eight exits (henceforth called the triple T-maze; see Fig. 1), modified from a device described by Hughes (1967) in previous studies (e.g., Carbines et al. 1992;Houghtaling and Kight 2006;Hegarty and Kight 2014). The tested individuals were introduced to a start point (point S in Fig. 1), forced to turn to the right (R) at the initial curve, and then allowed to select left (L) or right (R) at the subsequent three T-junctions when moving. ...
... Furthermore, in two trajectories (R-RRL and R-LLL), individuals performed one TA out of the three T-junctions. Since evidence shows that the degree of linearity from the start position differs even among individuals with the same number of TAs, the total number of TAs used in many previous studies on terrestrial isopods (Carbines et al. 1992;Houghtaling and Kight 2006;Hegarty and Kight 2014) is insufficient to understand linearity with continuous TA. This inconsistency also occurs when considering the actual distance from start to exit. ...
Turn alternation (TA) is the tendency to turn in the opposite direction of an immediately preceding turn when moving forward, resulting in an overall linear trajectory. TA has been observed in many animals, and terrestrial isopods are considered model organisms for studying TA. Optimizing their fleeing speed and trajectory helps isopods efficiently escape from predatory threats. However, since reproduction induces morphological and physiological changes, individuals might adjust their trajectories depending on their altered mobility. In this study, we investigated the effect of reproduction-related factors on the frequency of TA, which enables linearity, in the common rough woodlouse Porcellio scaber. The results showed that breeding females enhanced their linearity more than nonbreeding females and males. Furthermore, females without access to a potential mate enhanced their linearity more than females and males with access to a potential mate and maintained a high linearity for approximately 40 days. In terrestrial isopods, continuous TA for linearity may be used to avoid reproductive failure because of lack of encounters with the potential mate or to compensate for low running ability due to physical or physiological loads. Conversely, individuals that do not need to worry about reproductive failures or individuals with small loads could perform the random turn that does not require learning or memory. This is the first study to show that the events involved in reproduction affect the linearity shown by continuous TA in terrestrial isopods.
... Porcellio scaber Latreille, 1804 more intensively alternated turns when they met a spider (e.g., the dangerous Dysdera crocata CL Koch, 1838) than when they met a harmless fly or cotton flock (Carbines et al. 1992). Chronic stress induced by indirect predatory cues (e.g., ant odour) can lead to increased turn alternation in P. laevis and A. vulgare (Hegarty and Kight 2014), behaviour that leads to the desertion of a dangerous place. Also, these isopods can use small chronical substrate vibrations for the detection of a predator (Zimmerman and Kight 2016). ...
... Habituation to the disturbance can significantly reduce turn alternation (Houghtaling and Kight 2006). The similarity in turn alternation of distantly related species of terrestrial isopods suggests evolutionary conservation of these antipredator mechanisms (Hegarty and Kight 2014). It is also known that this escape behaviour is a result of the isopod's own decision-making (Moriyama 1999;Moriyama and Migita 2004) and that A. vulgare can correct its turns to increase its level of alternation (Moriyama et al. 2016). ...
Terrestrial isopods (Oniscidea) represent a widespread group of land Crustacea that have been able to successfully adapt to the terrestrial environment and occupy newly formed ecological niches. During the colonisation of land, they faced numerous challenges, including finding an effective way to avoid their new terrestrial predators. In response to predation pressure, they have developed various behavioural and morphological adaptations. These include tonic immobility, conglobation, clinging to the ground, releasing strongly acidic secretions, jumping, and efficient running away. Furthermore, terrestrial isopods can aggregate with other individuals, use stridulation, or change their typical activity time. Some of them also developed spiny tergites and aposematic colouration or posture. The majority of these strategies have not yet been studied.
... They have to solve existential problems to fulfil their necessities, such as the need for water or moisture (Cloudsley-Thompson 1956), food (Brody and Lawlor 1984), shelter (Allee 1926), and mating (Sutton 1972). This all takes place at constant risk of predation, either by one's own kind (cannibalism) (Sutton 1972) or by other species such as spiders (Gorvett 1956), ants, birds, amphibians, and mammals (Hegarty and Kight 2014). If isopods suffer from a deficiency or excess of any of these factors or the risk of predation, their behaviour may be affected (Sutton 1972). ...
... Animals are likely to interpret species-specific and non-specific substrate-borne stridulations as a source of potential danger . Turn alternation as an antipredatory strategy of woodlice has been examined by many authors such as Carbines et al. (1992), Houghtaling and Kight (2006), Hegarty and Kight (2014), and Cividini and Montesanto (2018b). ...
This study was focused on behaviour of the Common Rough Woodlouse ( Porcellio scaber ) and the Plum Woodlouse ( Porcellionides pruinosus ) under the influence of stressors in the form of increased temperature, the vibrating surface, or their combination. Two types of experiments were performed. First, woodlice placed in a labyrinth were observed, to determine the degree of turn alternation, the speed of passing through the labyrinth, and the corrections of turn alternation, when exposed to stressors. In the second experiment how woodlice aggregate in the aforementioned potential stressors was recorded and whether the change in aggregation behaviour can be an indicator of the degree of stress. Increased temperature and the combination of increased temperature and vibrations were stressors only for P. scaber . The results show that vibrations are not a stress factor for P. scaber or P. pruinosus . Porcellio scaber passed through the labyrinth more slowly at increased temperatures, and although they made more turn-corrections, they alternated turns less intensely. Its aggregation behaviour was mainly influenced by temperature, which confirms that the aggregation behaviour of P. scaber actually indicates a degree of stress.
... Hughes (1989) described the tendency to turn to the opposite side following an immediately preceding turn in many invertebrates. Alternating turn behavior may depend on particularly unfavorable conditions such as food deprivation (Hughes 1978), excessive disturbance at the level of substrate (Houghtaling and Kight 2006), signals from indirect predators (Hegarty and Kight 2014), or presence of predators (Carbines et al. 1992;Hughes 1967Hughes , 1978. Vibrations studied by Houghtaling and Kight (2006), however, were mainly generated inside an urban and rural environment contaminated by human activities, and, for this reason, not comparable in intensity and frequency with those generated in a natural environment. ...
... In many species of terrestrial isopods, turn alternation has been supposed to be a natural reaction of animals towards particularly unfavorable environmental conditions. Food deprivation (Hughes 1978), an excess of disturb at the level of substrate (Houghtaling and Kight 2006), signals coming from indirect predators (Hegarty and Kight 2014), and exposure to predators (Carbines et al. 1992;Hughes 1967Hughes , 1978 can lead an increased number of alternating turns. In a previous work (Cividini and Montesanto 2018), we proved the existence of a statistically significant association between the pattern of turn alternation and both exposure to substrate-borne vibrations and species of the animals. ...
In this study, we focused on the relationship existing between the phenomenon of alternating turns and substrate-borne vibrations in woodlice, utilizing Armadillo officinalis as an experimental behavioral model. A T-maze with multiple exits was used to collect information on the pattern of turn alternation in (i) adult individuals of A. officinalis exposed and (ii) non-exposed to micro-vibrations, and (iii) juveniles of A. officinalis exposed to micro-vibrations. Turn alternation was assessed as the number of times that an animal turned on the opposite side in the T-maze. Our best model pointed out a statistically significant increased expected number of alternating turns for both groups of adult individuals, non-exposed and exposed to micro-vibrations, compared to exposed juveniles. Adults of A. officinalis seem to be very reactive to substrate-borne vibrations, unlike juveniles. This reactivity might be related to a defense mechanism developed as an evolutionary adaptation to the xeric environment, increasing progressively from the juvenile condition until the adult state. This feature might also fit into a complex network of inter- and intraspecific communication mediated by substrate-borne vibrations, like in insects.
... In nature, moving in a straight line is considered the most adaptive strategy to adopt when there is no precise information about environmental resources or hazards [11]. Experimental results have suggested that sequential alternation of turns facilitates foraging [12] and escaping from biologically unfavorable conditions (food deprivation [10], vibrational disturbance [13], exposure to predators [14], indirect predator cue [15], being touched [16]). Additionally, it is known that pill bugs can correct its turns using directional change to increase its level of alternation [17]. ...
In this study, whether pill bugs produce turn alternation, i.e., the tendency to turn in the opposite direction of a preceding turn, under obstacle-free conditions was investigated by movement measurements using an omnidirectional motion compensator ANTAM. The results showed that turn alternation was observed at the microscopic observation level (sampling frequency 10 Hz). On the other hand, repeated turns in the same direction were observed more often than turn alternations at the macroscopic observation level (1 Hz). These results suggest that under obstacle-free conditions, the pill bug moves in a microscopic left–right and macroscopic arc, and that it has at least two turn control mechanisms.
... This is a simple and wide-spread strategy to avoid attacks of enemies (Parmentier et al. 2018;Ospina et al. 2022). It was also documented that Porcellio species make use of avoidance behaviour when confronted with other negative conditions, such as the presence of toxins (Zidar et al. 2019) or predator cues (Hegarty and Kight 2014). In addition, they likely benefit from a hard, protective exoskeleton (cf von Beeren et al. 2021) and low concentrations of chemical recognition cues on the cuticle (Parmentier et al. 2017). ...
The balance between costs and benefits is expected to drive associations between species. While these balances are well understood for strict associations, we have no insights to which extent they determine facultative associations between species. Here, we quantified the costs of living in a facultative association, by studying the effects of red wood ants on the facultatively associated isopod Porcellio scaber. Porcellio scaber frequently occurred in and near hostile red wood ant nests and might outnumber obligate nest associates. The facultative association involved different costs for the isopod. We found that the density of the isopod decreases near the nest with higher ant traffic. Individuals in and near the nest were smaller than individuals further away from the nest. Smaller individuals were also found at sites with higher ant traffic. A higher proportion of wounded individuals was found closer to the nest and with higher ant traffic. We recorded pregnant females and juveniles in the nest suggesting that the life cycle can be completed inside the nests. Lab experiments showed that females died sooner and invested less in reproduction in presence of red wood ants. Porcellio scaber rarely provoked an aggression response, but large numbers were carried as prey to the nest. These preyed isopods were mainly dried out corpses. Our results showed that the ant association incurred several costs for a facultative associate. Consequently, red wood ant nests and their surrounding territory act as an alternative habitat where demographic costs are offset by a stable resource provisioning and protection.
... Behavioral studies focusing on olfactory-guided behavior are rare for aquatic as well as terrestrial isopods (reviews: Warburg, 1993;Thiel, 2011), and behavioral responses for distant olfactory stimuli were contradictory for the isopod species investigated (compare Fischbach, 1951;Kuenen and Nooteboom, 1963;Kenning et al., 2015;andreview: Warburg, 1993 with, e.g., Nagel, 1894;Tait, 1927;Seelinger, 1983;Zimmer et al., 1996;Hegarty and Kight, 2014;Buzzelli, 2017). ...
Crustaceans provide a fascinating opportunity for studying adaptations to a terrestrial lifestyle because within this group, the conquest of land has occurred at least ten times convergently. The evolutionary transition from water to land demands various morphological and physiological adaptations of tissues and organs including the sensory and nervous system. In this review, we aim to compare the brain architecture between selected terrestrial and closely related marine representatives of the crustacean taxa Amphipoda, Isopoda, Brachyura, and Anomala with an emphasis on the elements of the olfactory pathway including receptor molecules. Our comparison of neuroanatomical structures between terrestrial members and their close aquatic relatives suggests that during the convergent evolution of terrestrial life-styles, the elements of the olfactory pathway were subject to different morphological transformations. In terrestrial anomalans (Coenobitidae), the elements of the primary olfactory pathway (antennules and olfactory lobes) are in general considerably enlarged whereas they are smaller in terrestrial brachyurans compared to their aquatic relatives. Studies on the repertoire of receptor molecules in Coenobitidae do not point to specific terrestrial adaptations but suggest that perireceptor events – processes in the receptor environment before the stimuli bind – may play an important role for aerial olfaction in this group. In terrestrial members of amphipods (Amphipoda: Talitridae) as well as of isopods (Isopoda: Oniscidea), however, the antennules and olfactory sensilla (aesthetascs) are largely reduced and miniaturized. Consequently, their primary olfactory processing centers are suggested to have been lost during the evolution of a life on land. Nevertheless, in terrestrial Peracarida, the (second) antennae as well as their associated tritocerebral processing structures are presumed to compensate for this loss or rather considerable reduction of the (deutocerebral) primary olfactory pathway. We conclude that after the evolutionary transition from water to land, it is not trivial for arthropods to establish aerial olfaction. If we consider insects as an ingroup of Crustacea, then the Coenobitidae and Insecta may be seen as the most successful crustacean representatives in this respect.
... The protocol to collect lizard olfactory cues is a standard protocol already used several times to elicit social reactions in lizards (e.g. Cote & Clobert, 2007;Teyssier et al., 2014) and the woodlice are known to react to predator chemical cues (e.g., volatile ant cues, Hegarty & Kight, 2014). We also added two individuals that were crushed in a tube in each predator treatment as alarm cues of predation (Broly et al., 2013) and an empty tube in no predation treatments. ...
Organisms rarely experience a homogeneous environment. Rather, ecological and evolutionary dynamics unfold in spatially structured and fragmented landscapes, with dispersal as the central process linking these dynamics across spatial scales. Because dispersal is a multi-causal and highly plastic life-history trait, finding general drivers that are of importance across species is challenging but highly relevant for ecological forecasting.
We here tested whether two fundamental ecological forces and main determinants of local population dynamics, top-down and bottom-up control, generally explain dispersal in spatially structured communities. In a coordinated distributed experiment spanning a wide range of actively dispersing organisms, from protozoa to vertebrates, we show that bottom-up control, that is resource limitation, consistently increased dispersal. While top-down control, that is predation risk, was an equally important dispersal driver as bottom-up control, its effect depended on prey and predator space use and whether dispersal occurred on land, in water or in the air: species that routinely use more space than their predators showed increased dispersal in response to predation, specifically in aquatic environments. After establishing these general causes of dispersal, we used a metacommunity model to show that bottom-up and top-down control of dispersal has important consequences for local population fluctuations as well as cascading effects on regional metacommunity dynamics. Context-dependent dispersal reduced local population fluctuations and desynchronized dynamics between communities, two effects that increase population and community stability.
Our study provides unprecedented insights into the generality of the positive resource dependency of dispersal as well as a robust experimental test of current theory predicting that predator-induced dispersal is modulated by prey and predator space use. Our experimental and theoretical work highlights the critical importance of the multi-causal nature of dispersal as well as its cascading effects on regional community dynamics, which are specifically relevant to ecological forecasting.
... Turn alternation An increase in the phenomenon of turn alternation is a natural mechanism, present in various species of terrestrial isopods, to react against a particularly unfavorable condition-mainly, for example, food deprivation (Hughes, 1978), disturbance on the substrate (Houghtaling & Kight, 2006), signals from indirect predators (Hegarty & Kight, 2014), or exposure to predators (Carbines, Dennis, & Jackson, 1992;Hughes, 1967Hughes, , 1978. An increased number of alternating turns in animals was also observed by Hughes (1967) following their exposure to excessive light or to dry environments, and by Ono and Takagi (2006) following the artificial stimulation of animals. ...
Effective communication is essential in animal life to allow fundamental behavioral processes and survival. Communicating by surface-borne vibrations is likely the most ancient mode of getting and exchanging information in both invertebrates and vertebrates. In this review, we concentrate on the use of vibrational communication in arthropods as a form of intraspecific and interspecific signaling, with a focus on the newest discoveries from our research group in terrestrial isopods (Crustacea: Isopoda: Oniscidea), a taxon never investigated before in this context. After getting little attention in the past, biotremology is now an emerging field of study in animal communication, and it is receiving increased interest from the scientific community dealing with these behavioral processes. In what follows, we illustrate the general principles and mechanisms on which biotremology is based, using definitions, examples, and insights from the literature in arthropods. Vibrational communication in arthropods has mainly been studied in insects and arachnids. For these taxa, much evidence of its use as a source of information from the surrounding environment exists, as well as its involvement in many behavioral roles, such as courtship and mating, conspecific recognition, competition, foraging, parental care, and danger perception. Recently, and for the first time, communication through surface-borne waves has been studied in terrestrial isopods, using a common Mediterranean species of the Armadillidae family as a pilot species, Armadillo officinalis Duméril, 1816. Mainly, for this species, we describe typical behavioral processes, such as turn alternation, aggregation, and stridulation, where vibrational communication appears to be involved.
... Os hábitos dos isópodes podem mudar quando submetidos à presença constante de predadores. Até mesmo rastros deixados por inimigos naturais -como, por exemplo, trilhas químicas produzidas por formigas -são capazes de modificar o comportamento de forrageio desses crustáceos (HEGARTY; KIGHT, 2014). ...
Este livro é composto por 17 capítulos que abordam diferentes temáticas como: trajetória de cultivo na Bahia, ecofisiologia e ambiente, indução de resistência ao ataque de patógenos, melhoramento genético, produção de mudas, biologia, física, química e manejo de solos, nutrição e adubação, irrigação, mecanização e sustentabilidade de sistemas agrossilviculturais com o cacaueiro.
... In several species of terrestrial isopods, an increased frequency of alternating turns has been considered as a natural reaction of animals towards an unfavorable condition; food deprivation (Hughes, 1978), excessive disturbance at the level of substrate (Houghtaling and Kight, 2006), signals from indirect predators (Hegarty and Kight, 2014), or exposure to predators (Carbines et al., 1992;Hughes, 1967Hughes, , 1978. Hughes (1967) proved an increase in turn alternations when isopods were kept in conditions of excessive light, or in dry environments. ...
The present study focuses on the relationship existing between the phenomenon of turn alternation and substrate-borne vibrations in woodlice. Armadillo officinalis was utilized as a behavioral model in comparison to Armadillidium vulgare so as to assess its capability of perceiving external vibrations too. A T-maze with multiple exits was used to collect information on the pattern of turn alternation in i) adult individuals of A. officinalis exposed, and ii) not exposed to micro-vibrations, and iii) adult individuals of A. vulgare exposed to micro-vibrations. Turn alternation was assessed as the number of times that an animal turned on the opposite side in the T-maze. Our results showed a statistically significant association between turn alternation pattern and both exposure to micro-vibrations and species of the animals. According to our best-fitting model, A. officinalis not exposed and A. vulgare exposed to substrate-borne vibrations have 97% and 98% lower odds, respectively of being in a higher category of turn alternations compared to a lower category than exposed individuals of A. officinalis. A. officinalis seems to be very reactive to substrate-borne vibrations, unlike A. vulgare. This different reactivity might be related to a more complex defense mechanism developed as an evolutionary adaptation to the xeric environment, and/or to a means of communication mediated by substrate-borne vibrations, like in insects.
... There is a need for studies in which prey species interact directly with living predators, as studies of antipredator behavior tend to use simulated (e.g., Wilson et al. 2010, Dupuy et al. 2011, Hedrick 2013; but see Camhi et al. 1978, Carbines et al. 1992 or indirect predator cues (e.g., Hoefler et al. 2012, Hegarty andKight 2014). For example, Beleznai et al. (2015) found that leafhoppers, Psammotettix alienus Dahlbom, 1850, changed foraging movement patterns in the direct presence the spider, Tibellus oblongus Walckenaer, 1802. ...
Comparisons of multiple invertebrate prey species to direct predator sensory cues are relatively uncommon. We compared prey responses to arachnid predators (Araneae: Lycosidae) of four species: Blattella germanica (Blattodea: Blattellidae), Acheta domesticus (Orthoptera: Gryllinae), Armadillidium vulgare (Oniscidea: Armadillidae), and Porcellio laevis (Oniscidea: Porcellionidae). Prey experienced combinations of direct mechanosensory, chemosensory or visual cues. All species responded to all cues, but response structure differed among species. Mechanosensory and chemosensory predator cues elicited frequent shifts between behaviors, whereas visual stimuli tended to diminish responses. Mechanosensory stimuli produced the most extreme responses, particularly in crickets and cockroaches, but responses to mechanosensory stimuli diminished when accompanied by visual stimuli. Crickets were particularly sensitive to chemical cues and reduced activity in response to them. Isopods were sensitive to visual stimuli, reducing activity in response. These behavioral similarities and differences provide insight into the sensory ecology of different species of arthropod.
... Terrestrial isopods kept in bright, dry environments (Hughes, 1967), and those given artificial stimulation (Ono and Takagi, 2006) before testing, have been reported to make more alternating turns. Likewise, food deprivation (Hughes, 1978), excessive substratum disturbance (Houghtaling and Kight, 2006), indirect predator cues (Hegarty and Kight, 2014), and exposure to predators (Carbines et al., 1992;Hughes, 1967Hughes, , 1978 are all associated with increased alternating turns. Unlike these situations, although we reduced our handling of the animals as much as possible to avoid stimulating them, they made more alternating turns. ...
Pill bugs (Armadillidium vulgare) demonstrate a behavior called turn alternation that keeps their overall direction of movement straight after obstacles in experimental settings force them to deviate from a course. For example, this behavior is seen when they alternate their path choice on successive trials of the T-maze test. However, sometimes pill bugs stop after turning and change their direction (directional change). The function of this directional change has not been investigated because such individuals are usually omitted from the data. The present paper shows that pill bugs use directional changes to prevent them from turning in the same direction on two successive turns, a behavior called turn repetition. We examined the behavior of 36 pill bugs that each completed 130 successive T-maze trials. Directional changes appeared more frequently when individuals had begun a turn repetition than when they had begun a turn alternation. Furthermore, after correcting for turn repetition, turn alternations increased. These results suggest that pill bugs have an inherent mechanism that acts to maintain turn-alternating behavior.
Pill bug is an arthropod of about 1 cm in length that lives under fallen leaves and stones. When it turns in an L-shaped passage and encounters a T-maze next, it turns in the opposite direction of the turn in the L-shaped passage mostly. This reaction is called turn alternation. In this paper, we report our experiments to investigate whether pill bugs have a tendency to keep turn alternation or not in a pathway where the distance between the L-shaped passage (forced turn point) and the T-maze (free choice point) is long. Our results suggest that some pill bugs tend to decrease turn alternation, i.e., increase turn repetition, as the distance between the forced turn and free choice points is longer. In nature, these pill bugs may use turn alternation in places where there are many obstacles like stones and dead leaves and do turn repetition in those such as sandy squares with sunlight where there are few obstacles.
Turn alternation is a locomotory behaviour wherein an animal makes consecutive turns in opposite directions (left-then-right or right-then-left). It has been suggested that its adaptive function is to maintain locomotion in a relatively constant general direction while negotiating obstacles. Previous work has focussed on the use of turn alternation in prey species in artificial horizontal mazes. In the first study presented here, we tested whether predatory seven-spot ladybirds (Coccinella septempunctata) exhibit turn alternation when repeatedly presented with consecutive choice turning decisions on vertically oriented twigs. Our findings suggest that turn alternation occurs vertically as well as horizontally, on plant structures as well as terrestrially, and in a type of animal (predatory insect) in which turn alternation has received little attention. In the second study presented here, we tested whether characteristics of branched structures explored by two-spot ladybirds (Adalia bipunctata) influence turning decisions. Our findings suggest that ladybirds exhibit preferences for thicker over thinner, straighter over more deviating headings, and higher over lower turning choice options at bifurcations. These exploratory studies indicate that while turn alternation is an observable phenomenon in ladybirds, it is not the only predictor of searching behaviour on branched structures.
In recent years, various animal observation instruments have been developed to support long-term measurement and analysis of animal behaviors. This study proposes an automatic observation instrument that specializes for turning behaviors of pill bugs and aims to obtain new knowledge in the field of ethology. Pill bugs strongly tend to turn in the opposite direction of a preceding turn. This alternation of turning is called turn alternation reaction. However, a repetition of turns in the same direction is called turn repetition reaction and has been considered a malfunction of turn alternation. In this research, the authors developed an automatic turntable-type multiple T-maze device and observed the turning behavior of 34 pill bugs for 6 h to investigate whether turn repetition is a malfunction. As a result, most of the pill bug movements were categorized into three groups: sub-diffusion, Brownian motion, and Lévy walk. This result suggests that pill bugs do not continue turn alternation mechanically but elicit turn repetition moderately, which results in various movement patterns. In organisms with relatively simple nervous systems such as pill bugs, stereotypical behaviors such as turn alternation have been considered mechanical reactions and variant behaviors such as turn repetition have been considered malfunctions. However, our results suggest that a moderate generation of turn repetition is involved in the generation of various movement patterns. This study is expected to provide a new perspective on the conventional view of the behaviors of simple organisms.
Ecology and evolution unfold in spatially structured communities, where dispersal links dynamics across scales. Because dispersal is multicausal, identifying general drivers remains challenging. In a coordinated distributed experiment spanning organisms from protozoa to vertebrates, we tested whether two fundamental determinants of local dynamics, top-down and bottom-up control, generally explain active dispersal. We show that both factors consistently increased emigration rates and use metacommunity modelling to highlight consequences on local and regional dynamics.
Spontaneous alternation refers to the tendency of organisms to explore places that they have least recently visited. Our previous work showed that alternation performance of Carcinus maenas (invasive European green crab) was significantly higher than Callinectes sapidus (native blue crab), and chance level performance (Ramey, P. A., Teichman, E., Oleksiak, J., & Balcı, F. [2009]. Spontaneous alternation in marine crabs: Invasive versus native species. Behavioural Processes, 82, 51–55.). In the current study, we first tested the robustness of these findings in the absence of visual cues, longer test durations, and wider maze dimensions. These manipulations enabled us to determine whether these two crab species relied on the visual cues provided during the spontaneous alternation task in our prior work, and allowed for better characterization of their exploratory activity in the maze. Our original findings were reproduced in the present study under these new task conditions, suggesting no role for visual cues during alternation, and emphasizing the robustness and generalizability of the corresponding interspecies differences in alternation performance. We also tested whether the lower alternation performance of C. sapidus also applied to another native crab species, Uca pugnax (fiddler crab). Spontaneous alternation performance of U. pugnax was significantly lower than C. maenas but indistinguishable from C. sapidus. Finally, we examined whether the potentially higher inherent risk-sensitivity of C. sapidus could have contributed to their lower alternation performance by testing C. maenas in the presence of a larger natural predator (stressor). Higher risk sensitivity presumably induced by the stressor led to locomotor activity patterns that better resembled those of C. sapidus, however the resultant reduction in alternation performance was not statistically significant.
Three different types of prey-preference tests were carried out using Dysdera crocata, a spider frequently described as a specialist predator of woodlice. None of these tests provided evidence that Dysdera crocata prefers woodlice over a variety of insect prey (house flies, beetle larvae, mirid bugs, moths and crickets). We also ran prey preference tests with two species of woodlice that differ in their behavioural and chemical defences, and there was no evidence of preference for either of these species over the other. The broader question of whether D. crocata is a specialized predator in any respect is discussed.
Shows that contact with a spider that preys on woodlice (WL) influences the correcting behavior of WL. The test apparatus used was a modification of R. N. Hughes (1967) maze. Hughes proposed that correcting behavior may function to facilitate efficient movement away from unfavorable conditions. In an experimental test, a woodlouse was put in the starting chamber with a predatory spider. In a control test, a woodlouse was put in the starting chamber with either a ball of cotton wool or a fly. There were 100 trials for each of the 3 treatments. Results support Hughes' hypothesis by providing evidence that WL react to the presence of a predator by increasing their rates of alternating turns. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Equal investment within broods does not always maximize parental reproductive value if the reproductive value of some of the young is low. We examined maternal investment in terms of offspring size in relation to the prospects of survival from predation within broods of the shield bug Elasmucha ferrugata Fabr. (Heteroptera; Acanthosomatidae). Shield bug females guard eggs and first instar nymphs against invertebrate predators by covering the clutch with their body and by behaving aggressively towards their enemies. Survival of eggs was not possible without maternal care. When females were allowed to guard their brood, eggs at the periphery were more vulnerable to predators than eggs at the centre. We found that females laid significantly larger eggs in the safest, central part of the clutch. There seems to be an advantage of large nymph size, since when nymphs were reared separately with low food resources, the larger ones were more likely to survive. Larger nymphs were also more likely to push themselves to the safest, central part of the clutch. Females seem to allocate their resources more to the offspring with the highest probability of avoiding predation. Thus our study supports unequal maternal investment within broods of E.ferrugata.
We used foraging trays to determine whether oldfield mice, Peromyscus polionotus, altered foraging in response to direct cues of predation risk (urine of native and nonnative predators) and indirect cues of predation risk (foraging microhabitat, precipitation, and moon illumination). The proportion of seeds remaining in each tray (a measure of the giving-up density [GUD]) was used to measure risk perceived by mice. Mice did not alter their GUD when presented with cues of native predators (bobcats, Lynx rufus, and red foxes, Vulpes vulpes), recently introduced predators (coyotes, Canis latrans), nonnative predators (ocelots, Leopardus pardalis), a native herbivore (white-tailed deer, Odocoileus virginianus), or a water control. Rather, GUD was related to microhabitat: rodents removed more seeds from foraging trays sheltered beneath vegetative cover compared with exposed trays outside of cover. Rodents also removed more seeds during nights with precipitation and when moon illumination was low. Our results suggest that P. polionotus used indirect cues rather than direct cues to assess risk of vertebrate predation. Indirect cues may be more reliable than are direct scent cues for estimating risk from multiple vertebrate predators that present the most risk in open environments. Copyright 2004.
Little is known about the flow of chemical information from higher to lower levels within the animal food chain. However, this information may determine the behavior and distribution of many animals (e.g., that of potential prey) when exposed to direct and indirect cues of predation risk. We used herbivorous spider mites, Tetranychus urticae Koch (Tetranychidae) as a model to examine the foraging and oviposition decisions that prey make when exposed to these cues. We conducted laboratory tests to determine if the previous presence of predators (direct cues) on leaf discs or the presence of injured conspecifics (indirect cues) alters the distribution of adults and eggs of T. urticae. When given a choice, after 24 h, fewer adults and eggs were found on leaf discs that had previously contained specialist spider mite predators, Phytoseiulus persimilis Athias-Henriot (Phytoseiidae), than on discs unexposed to predators. Also, more T. urticae emigrated from predator-exposed discs than from unexposed discs or from those that had previously contained nonpredatory mites (Tyrophagus putrescentiae, Acaridae). Finally, fewer T. urticae foraged and laid eggs on predator-exposed discs or on those with artificially damaged conspecifics (eggs or dead adults) than on discs with intact conspecifics. Tetranychus urticae probably recognizes infochemicals (kairomones) from its predators or cues from injured spider mites and consequently avoids feeding or ovipositing in areas exposed to these cues. Recognition and avoidance of kairomones from specialist predators by this prey are likely to be hereditary, but avoidance of injured conspecifics may be an adaptation to avoid predators that are not inherently recognized. We discuss the behavioral and ecological implications of our findings.
Little is known about the effects of predatory stress on reproduction in terrestrial isopods (Crustacea: Oniscidea). We studied direct and indirect influences of predatory ants Tetramorium caespitum (Hymenoptera: Formicidae) on the behavior and reproduction of two terrestrial isopods, Armadillidium vulgare and Porcellio laevis. A. vulgare females were more cryptic than P. laevis females in both the presence and absence of ants, but in both species control animals were more cryptic than experimental animals exposed to ants. This likely resulted from increased movement in the presence of ants. Both species also avoided ventilated enclosures containing ants, but control animals not previously exposed to ants remained significantly further away. P. laevis also remained significantly further from ants than A. vulgare, suggesting that P. laevis more actively avoids potential predators. This is consistent with morphological differences between the two species: A. vulgare can roll into a sealed ball whereas the morphology of P. laevis permits swift locomotion. Furthermore, mortality rates of P. laevis were greater than A. vulgare when both were directly exposed to ants in the laboratory, and P. laevis suffered significantly more attacks than A. vulgare under experimental conditions. However, the length of the brooding period in A. vulgare was shorter in ant-exposed females than in controls, whereas experimental and control P. laevis females showed no such difference. This could be an adaptive trade-off for A. vulgare because in the late brooding period the distended marsupium can prevent rolling into a closed ball for protection. The results of this study underscore the relationships between morphology, behavior, and reproductive success.
We used giving-up densities in food patches to measure the effects of several direct (left by the predator) and indirect (environmental correlates of risk) cues of predatory risk on the foraging behavior of free-living fox squirrels ( Sciurus niger ) and thirteen-lined ground squirrels (Spermophihis tridtctmlineatus). Increases in giving-up density in response to stimuli allow quantitative comparisons of the effects of different types of cues. We used olfactory (urine of red fox) and visual (plastic models of owls) direct cues. As indirect cues, we used mkrohabitat (near or far from a refuge), background coloration (white, green, and brown tarpaulins), and escape substrate (canvas tarpaulins versus natural surrounding substrates). Both squirrel species responded most strongly to microhabitat Fox squirrels increased their giving-up density by 97% when feeding 4–6 m from a tree compared to feeding at the tree base. Thirteen-lined ground squirrels increased giving-up densities 84% when feeding 2 m from their burrows compared to feeding at the burrow entry. In response to an unfavorable escape substrate (canvas versus grass), fox squirrel giving-up densities increased 61%. Fox squirrels and ground squirrels increased giving-up densities 26% and 35%, respectively, in response to a plastic owL Background coloration had no demonstrable effect on the giving-up densities of fox squirrels. In contrast to other work on nocturnal mammalian herbivores and granivores, the diurnal fox squirrels did not respond to olfactory cues.
The complex collective behavior seen in many insect societies strongly suggests that a minimum number of workers are required for these societies to function effectively. Here we investigated the transition between disordered and ordered foraging in the Pharaoh's ant. We show that small colonies forage in a disorganized manner, with a transition to organized pheromone-based foraging in larger colonies. We also show that when food sources are difficult to locate through independent searching, this transition is first-order and exhibits hysteresis, comparable to a first-order phase transition found in many physical systems. To our knowledge, this is the first experimental evidence of a behavioral phase transition between a maladaptive (disorganized) and an adaptive (organized) state.
Research concerned with spontaneous alternation behavior in rats is examined and related to learning theory. It is concluded that alternation behavior can no longer be adequately interpreted in terms of Hull's concept of reactive inhibition. The notion of stimulus satiation as an explanation of alternation behavior has received general support from the research literature, but some data seem to require a more general theoretical explanation. Motivational concepts such as curiosity are suggested. 47 references. (PsycINFO Database Record (c) 2006 APA, all rights reserved).
The woodlouse Oniscus asellus (Crustacea, Isopoda, Oniscoidea), when disturbed, discharges droplets of a sticky fluid from a pair of projections (uropods) at its rear. The fluid coagulates on exposure to air, and acts effectively to entangle attacking ants. Analyses showed the secretion to be proteinaceous and unusually rich in glycine and proline. Its coagulation may be due to a polymerization process.
Seventy-five children of preschool age were observed in a cross-maze. The frequency of alternation increased with age for the Ss who started both trials from the same start position but did not change across age for the Ss who started the two trials from opposite start stems. Running time decreased with increasing age under both conditions.
Diese Arbeit befaßt sich mit dem Verhalten der Rollassel Armadillidium vulgare (Latreille, 1804), das zum Temperaturausgleich führt. Es wurde beobachtet, daß diese Landisopoden Unterschlüpfe suchen, in denen die Temperaturschwankungen der Umgebung gemindert werden. In Laboratoriumsversuchen zeigte sich die Rollassel in der Lage, in einem Wärmegradienten ein gewisses Temperaturgebiet (22-23°C) mit einer relativen Genauigkeit zu wählen. Diese Vorzugstemperatur kann leicht durch einen Konflikt zwischen der Thermotaxis und der Thigmotaxis, Phototaxis oder Hygrotaxis verändert werden. Des weiteren kann diese Vorzugstemperatur durch vorherige Gewöhnung an Kälte (12°C) oder Wärme (32°C) um einige Grade nach unten verschoben werden. Unter Wärmeeinfluß gesellen sich die Rollasseln zu Gruppen zusammen, was wahrscheinlich zu einem geringeren Wasserverlust führt. Eine andere wichtige Eigenschaft des Verhaltens dieses Tieres ist die Möglichkeit, Verbindungen zwischen thermischen und optischen oder chemischen Reizen zu lernen. Es wurden keine Beweise gefunden, daß die Rollassel sich bei Kälte in tiefere Erdlöcher verkriecht; jedoch wurde beobachtet, daß bei Temperaturen unter dem Gefrierpunkt die Rollassel in ein Schlafstadium verfallt. Zuletzt wurde noch festgestellt, daß die Rollassel, obwohl sie tagaktiv ist, diesen Zyklus umkehren kann, wenn die Temperaturen in der Helligkeitsphase erhöht (30°C) und in der Dunkelphase neutral (20°C) gelassen werden.
Pygmy shrews were snap-trapped over one year in grassland and occasionally in other habitats. The bodies yielded data on tooth-wear, body and skull dimensions, moulting, reproduction, food and parasites. The shrews appeared equally abundant in grassland and woodland and were more active in the day. The breeding season, population turnover, and winter body and skull regression were similar to those of other Sorex species. However, cranial regression was more marked: this may be associated with the animal's exceptionally small size. Moulting extended in autumn from August to November, and in spring from March to May, the latter in males starting earlier and perhaps lasting longer. Simultaneous and patch moults were also recorded. The litter size dropped as the breeding season progressed. The main foods were beetles, woodlice, Diptera and insect larvae; all except Diptera were eaten consistently over the year. There was a wide variety of other foods, many showing seasonal fluctuations. The commonest flea was Doratopsylla dasycnema. Palaeopsylla soricis, a common shrew-flea, widespread in the British Isles, is at least locally absent. Pygmy shrews may be the principal host of Hystrichopsylla talpae in Ireland. Rates of infestation by the trematodes and one cestode appeared to increase as the hosts aged. The tapeworm Hymenolepis scutigera, however, was commonest in juveniles. It is postulated that Doratopsylla dasycnema is its intermediate host, allowing infection of young before they leave the nest. Sorex araneus is sympatric with Sorex minutus over most of its range, but not in Ireland. In its absence, S. minutus may have been able to exploit its niche, the apparent abundance of the latter in woodland and wider variety of food consumed providing grounds for such a hypothesis.
Free-choice behavior following one or more forced turns was observed in representatives of four invertebrate classes (earthworms, woodlice, millipedes, earwigs). While all animals alternated, species differences occurred in free turn angle and the effects of varied angle and number of forced turns. Overall, woodlice and millipedes turned at sharper angles and responded more to the forced turn conditions than earthworms and earwigs. From behavior observed following three forced turns in one direction and then one in the opposite, it was concluded that, in earlier experiments, earthworms alternated via tactile cues, woodlice mainly used kinesthetic but could also use tactile cues, millipedes mainly used tactile but could also use kinesthetic cues and earwigs may have relied on kinesthetic cues alone. Since phyletic differences did not seem appropriate, the results were discussed in terms of other characteristics such as body shape and life style.
This study attempts to control thigmotaxis and centrifugal swing as the basic factor in the alternation behaviour of the meal worm, larvae of Tenebrio molitor. In order to eliminate these variables, alleyways of the mazes were essentially V-shaped in construction. As a result, centrifugal swing to one side or another is substantially reduced and since the construction of the maze guarantees contact on both sides of the organisms' body, thigmotaxis control in determining turning behaviour is eliminated. Four mazes were employed in this study. Two of the mazes had a 3 cm. alleyway from forced turn to T-choice. These mazes were mirror images of each other; the direction of forced turn being right for one and left for the other. Two of the mazes had a 6 cm. alleyway from forced turn to T-choice. These mazes were mirror images of each other. All mazes were pre-tested for bias by using only the T portion of the maze. The distribution of right and left turns in the pretest for all mazes did not differ significantly from chance. In the basic study, 512 meal worms were employed with N = 128 for each maze. In both the 3 cm. and 6 cm. maze (combined mirror image), the tendency to turn in the opposite direction from the forced turn was highly significant. The magnitude of the effect decreases significantly from the 3 cm. to the 6 cm. maze. These findings duplicate the original findings of Grosslight & Ticknor (1953). The results in relation to the concepts of reactive inhibition, the original hypothesis, and the alternate explanations of centrifugal swing and thigmotaxis are discussed.
It is well documented that animals take risk of predation into account when making decisions about how to behave in particular situations, often trading-off risk against opportunities for mating or acquiring energy. Such an ability implies that animals have reliable information about the risk of predation at a given place and time. Chemosensory cues are an important source of such information. They reliably reveal the presence of predators (or their presence in the immediate past) and may also provide information on predator activity level and diet. In certain circumstances (eg, in the dark, for animals in hiding) they may be the only cues available. Although a vast literature exists on the responses of prey to predator chemosensory cues (or odours), these studies are widely scattered, from marine biology to biological control, and not well known or appreciated by behavioural ecologists. In this paper, we provide an exhaustive review of this literature, primarily in tabular form. We highlight some of the more representative examples in the text, and discuss some ecological and evolutionary aspects of the use of chemoscensory information for prey decision making. Curiously, only one example illustrates the ability of birds to detect predator odours and we have found no examples for terrestrial insects, suggesting a fruitful area for future study.
Foraging behaviour of Armadillidium vulgare was observed in laboratory arenas in which the spatial distribution of patches of high quality food (powdered dicotyledonous leaf litter) was varied within a background of low quality food (powdered grass leaf litter). The hypotheses that the foraging behaviour and foraging path of A. vulgare would be influenced by food quality and the patchiness of high quality food resources were tested. More time was spent in high quality food patches than in low quality food backgrounds than expected by chance in all heterogeneity treatments, but an increasingly higher percentage of time was spent in low quality food as the high quality food became more clumped in space. More time was spent searching, but less time was spent feeding in low quality food backgrounds than in high quality food patches in all the treatments. Walking speed was found to be lower in high quality food patches than in low quality food backgrounds and this was not affected by treatment. Turning frequency and turning angle were found to be higher in high quality food patches than in low quality backgrounds. Turning frequency in low quality food backgrounds decreased as the high quality food became more clumped in space, whereas turning angle in high quality food patches significantly increased in the patchy, but then decreased again in the clumped treatment. The effects of varying the spatial heterogeneity of high quality foods on the trade-off between costs of searching and intake benefits for saprophages are discussed in relation to predictions from optimal foraging theory for circumstances when intake rate maximisation is affected by the constraint of limited nutrients.
Terrestrial isopods are known to increase alternating maze turns in response to adverse environmental conditions, a behavioral pattern presumably associated with efficient escape. The present study investigates whether turning behavior in response to vibration disturbance differs between natural populations inhabiting disturbed and undisturbed areas. Some specimens were collected from urban habitat characterized by construction and heavy automobile traffic, and others from relatively undisturbed rural habitat less than 10 kilometers distant. We examined maze turn alternation in three groups: rural and urban terrestrial isopods exposed to vibration during testing, and rural isopods not exposed to vibration. As predicted, rural isopods exposed to vibration made significantly more turn alternations than rural isopods not exposed to vibration. However, rural vibration-exposed isopods also exhibited significantly greater turn alternation than vibration-exposed urban isopods. There was no significant difference between rural non-exposed and urban vibration-exposed isopods. These results indicate that isopods increase turn alternation when disturbed, but that previous exposure to disturbance is associated with a reduction in the effect. Whether this is due to acclimated or evolved behavioral mechanisms is presently unknown.
Four experiments observed turn alternation in about 400 garden woodlice in a multiple T-maze following blinding of one or both compound eyes, removal of one or both 2nd antennae, and deprivation of food for 24, 48, or 72 hrs. Blinding reduced alternation and increased trial durations, whereas the removal of antennae increased the latter but had no effect on the former measure. Blinding effects were seen as reflecting the results of decreased light input on locomotor speed upon which alternation is known to depend. The lack of a relationship between the 2 measures in antennectomized Ss may have been due to prior immobilization with carbon dioxide. Since visual, tactile, or chemical cues were not crucial for the occurrence of alternation, data were discussed in terms of alternation resulting from the greater inhibition of legs on one side; i.e., those that must walk farther and work harder in the course of negotiating a turn. Alternation was increased by 72 and durations by 24 hrs of food deprivation. Results support the view that alternation's survival value lies in its facilitation of rapid movement in a linear direction toward a more favorable environment. This view is further supported by a demonstration of high rates of alternation when Ss were confronted with obstacles in a comparatively natural environment. (12 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Woodlice ran faster in a straight runway when the floor was white than when it was black. When a runway with totally black or white floors (reflecting different levels of light) met up with equal areas of both brightnesses, woodlice turned in the direction of the runway brightness. Normal turn alternation after a forced turn was suppressed by this tendency to continue following the same substrate brightness when it involved moving in the direction of a repeating turn. However, when it involved turning in the direction of an alternating turn, the tendency to follow the same brightness had no effect on alternation.
In many species, prey detect predators using chemical cues, which may be based on the predator's previous diet. Furthermore, the predator's previous hunting strategy and diet may affect the prey's behavioural strategies to avoid predation. Juvenile Gryllid field crickets face predation by spiders, but the responses of juvenile crickets to spiders are unknown. We studied whether naïve juvenile field crickets can detect a predatory spider, Hololena nedra, using chemotactile cues (silk, secretions and excreta). We also studied the effect of the predator's diet on the juvenile field cricket's anti-predator behaviour. Cricket nymphs avoided the chemotactile spider cues when the spiders were previously fed with crickets, but not when spiders were not fed crickets. Our study suggests that the ability to detect the indirect cues of a potential predator may be an important factor determining the anti-predator responses of insects towards spiders.
The results of studies on the feeding ecology of spiders from 1974–1980 can be summed up as follows: All species of spiders examined fed exclusively on evertebrates (Insecta, Arachnida, Isopoda, Myriapoda, Lumbricidae). In most cases, more than 90% of the food consisted of insects.
Numerous spiders living in the vegetation stratum feed mainly on small flying insects, such as Diptera and aphids. The same is true for the dominant spiders living on the surface of the soil, though their prey spectrum is supplemented by Collembola and apterous aphids. Thus in the average prey spectrum of spiders small insects with a soft cuticle dominate. Exceptions are found withArgiope bruennichi, a predator of grasshoppers and bees,Agelena spp. feeding mainly on relatively large insects,Xysticus cristatus, which, when hunting on the ground, preys on ants and spiders,Achaearanea riparia, preying on ants and beetles,Coelotes terrestris, a specialized predator of beetles, andPholcus phalangioides, preying on wood-lice, spiders, opilionides etc. The prey spectra of the spider species examined vary considerably in breadth. So the food spectrum of the funnel-web spiders of the polyphagous genusAgelena is large compared to that of the oligophagousC. terrestris. Whereas in most spider species the size of their prey is relatively small or only reaches the size of the predator (size of prey ≤ size of predator), some species, mainly of Thomisidae and Theridiidae, prey at times upon prey larger than they are.
Spiders are secondary consumers belonging predominantly to herbivor food chains. Wolf spiders living on forest grounds intervene also in detritus food chains. Scorpionflies (genusPanorpa) often feed on prey animals in spider webs (food robbery).
Angles of free turn were observed in woodlice (Porcellio scaber) after they had been forced to turn left or right in runways. Alternation angles were increased by greater forced-turn angles
and number of successive forced turns in one direction. Removal of one or both antennae had no effect on alternation. It was
also repeatedly observed that the closer a woodlouse remained to the far wall while traveling along the exit alley of a runway,
the greater was its angle of alternation. However, orientation toward this far wall bore no relation to alternation. When
given three successive left or right forced turns followed by a fourth in the opposite direction, woodlice moved further away
from the exit-alley far wall and repeated the last forced turn at the choice area. Along with results of the other experiments,
this result in particular supported an explanation for woodlouse alternation based on bilaterally asymmetrical leg movements
(BALM) arising from the negotiation of forced turns. Such asymmetry is seen as biasing an animal to turn in the opposite direction
to a preceding forced turn.
Deflective displays direct predatory attacks to body parts that are relatively invulnerable or can be lost without disastrous consequences. Usually, these behaviors are directed to predators poised to attack at very close quarters. In contrast to such reactive deflection is anticipatory deflection in situations that entail a high risk of being ambushed. Because a predator can draw nearer during display, reactive deflection is feasible only when the predator is already close. A graphical model shows lines relating probability of death to distance from the predator when the prey displays and when it flees without display. Reactive deflection decreases the probability of death when the predator is closer than the intersection of these lines, but increases the probability of death beyond the intersection. If the predator is detected when far enough away, the best option is to flee without displaying. Anticipatory deflection may increase the probability of surviving ambush immediately after arriving at a new location but increase the risk of attracting the attention of other predators. This risk increases with time since stopping as more predators arrive that did not detect the prey moving to its new location. Anticipatory deflection can be selectively favored only during a brief interval immediately after the prey arrives. The interval increases with benefit of display to survival if ambushed. It decreases with increases in probabilities of being detected and killed due to display. Examples of these displays and other taxa in which they may be sought are discussed.
Organisms ranging from paramecia to humans tend to explore places that have been least recently explored, which is referred to as spontaneous alternation. Although organisms rely on different sources of information in alternating between places, the emergent behavioral pattern is likely advantageous during exploration and foraging. Under this rationale, continuous spontaneous alternation performance of the invasive green crab, Carcinus maenas was assessed and compared with the native blue crab, Callinectes sapidus in a plus-maze submerged in seawater. For the first time spontaneous alternation behavior was demonstrated in Crustacea (i.e., C. maenas) and significant interspecific differences in alternation performance were observed between the invasive versus the native species. Carcinus maneas exhibited a pronouncedly higher spontaneous alternation performance than C. sapidus. Carcinus maneas on average alternated at levels higher than chance, which was not the case for C. sapidus. These observations point to an additional behavioral mechanism that might result in the competitive success of green crabs over blue crabs in areas where they co-occur. Most of the subjects exhibited asymptotic alternation performance from the onset; there was no improvement in their performance over the course of the experimental session. This finding implies the innate nature of this behavioral policy.
Wild-caught adult Rana pipiens females were captured in midsummer and fed diets of crickets, flies sowbugs or wax moth larvae during a three-month period of active vitellogenesis. The cricket diet supported the most extensive body weight gain during this time and promoted a prolonged period of weight increase in an additional long-term study. Synchronous growth of the oocytes occurred in all four groups, but the ovaries and oviducts of cricket-fed animals were significantly larger than those of frogs on the other three diets. The significantly higher liver weights of frogs fed wax moth larvae may have reflected an augmentation of hepatic energy stores. Fat body weights were also highest in this group of animals. Frogs fed crickets and wax moth larvae possessed larger fat bodies than did the midsummer control animals killed immediately after their arrival in the laboratory. In contrast, frogs fed flies and sowbugs had smaller fat bodies than did the initial controls, suggesting that animals on these diets had utilized fat body lipid during vitellogenesis. Gastrocnemius and final body weights were lowest in frogs fed wax moth larvae. These findings may have reflected the nutritional content of the diet or the reduction in appetite frequently noted in these animals during observations of feeding behavior.
It was shown that response alternation frequency in woodlice became higher with the number of prior forced turns in one direction, but was unaffected by varied distance between the start and a forced turn. However, the frequency became lower with increased distance between a forced turn and a choice point, and also with detention following a forced turn. Woodlice kept in a bright, warm environment prior to testing made greater numbers of successive alternation responses in a multiple T maze and showed faster running speeds. It was concluded from this that adverse stimulation increases alternation merely by causing more rapid movement between turns. One possible adaptive function of response alternation in woodlice may be to insure efficient, direct movement away from a noxious area.
In nature, animals are exposed to a wide range of threats and dangers with predators being amongst the more prominent and intensely studied of these. The responses of prey to predators and various predator avoidance and antipredator behaviors have been extensively evaluated from ecological and ethological perspectives and more recent ethopharmacological and neuroscience approaches. Unfortunately, there has been relatively little interchange between the ecological-ethological and neuroscience areas with the latter often using responses to predators just simply as another 'model' system. There is, however, now a growing realization that integrative approaches incorporating ecological, evolutionary and neurobiological explanations are required for the understanding of behavior and its functions. This necessitates an incorporation of ecological and ethological concepts and validity with neuroscience approaches to the analysis of antipredator responses and defensive behavior. A number of selected ecological approaches that are used for the investigation of predator avoidance mechanisms and antipredator defensive behavior patterns are briefly reviewed here. These include examinations of how predation risk and its variation affect decision making in animals and how learning affects these responses. The trade-offs that are involved, how the risk of predation affects decisions concerning foraging behavior, mating and reproduction, as well as how varying levels of risk affect decisions relative to the type of defensive mechanisms utilized are briefly outlined. The utility of these approaches and their relevance to the design and interpretation of various neuroscience studies is addressed here.
Paramecia run through a single-T path, a T with a prior right or prior left turn, or T with 2 prior right or left turns, showed, particularly with the one prior turn, a marked "centrifugal swing" or "reactive inhibition." Distribution of turns in the single-T conformed to chance expectancy.
Spontaneous alternation behavior (SAB) is the universal tendency of animals, including unicellular organisms, to alternate directional choices at consecutive left/right branchings while traversing a maze. Occurrence of SAB implies short-term memory, as a current decision is statistically dependent on previous ones. We developed a procedure to assess SAB in human spermatozoa. A total of 1302 progressively motile spermatozoa from healthy donors were observed as they entered one of two mazes, both fabricated by eximer laser ablation. The control maze was a simple T-maze (width=depth=20 microm, distance between entrance and free choice T-intersection=600 microm). The experimental maze was identical to the control maze except for a forced right-turn 600 microm before the T-intersection. We recorded individual sperm cells' left/right decisions at the T-intersections in both mazes. Of the 714 spermatozoa entering the control maze, 49.1% turned to the left (not significantly different from the chance expectation of 50.0%). Of the 588 spermatozoa entering the experimental maze, 58.6% turned left after the initial forced right turn (significant SAB; P=0.041, Wilcoxon). The statistical dependency of a directional decision on a previous one suggests a physiological 'memory' in human spermatozoa. Among the possible underlying mechanisms are refractory processes in structures responsible for flagellar beating, a postulation which deserves further scrutiny with video-monitored single-cell testing.
Phase transition between disordered and ordered foraging in Pharoah's ants
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On the transpiration rates and temperature and humidity acclimation of the woodlice in Benghazi
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The death feint and other responses of the terrestrial isopod Porcellio scaber to a jarring stimulus
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On the transpiration rates and temperature and humidity acclimation of the woodlice in Benghazi, Libya
- Nair
Field Studies on feeding ecology of spiders: observations in the region of Zurich, Switzerland
- Nyffleler
Mechanisms for turn alternation in woodlice
- Hughes