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Pain and stress in crustaceans?
Abstract
We consider evidence that crustaceans might experience pain and stress in ways that are analogous to those of vertebrates. Various criteria are applied that might indicate a potential for pain experience: (1) a suitable central nervous system and receptors, (2) avoidance learning, (3) protective motor reactions that might include reduced use of the affected area, limping, rubbing, holding or autotomy, (4) physiological changes, (5) trade-offs between stimulus avoidance and other motivational requirements, (6) opioid receptors and evidence of reduced pain experience if treated with local anaesthetics or analgesics, and (7) high cognitive ability and sentience. For stress, we examine hormonal responses that have similar function to glucocorticoids in vertebrates. We conclude that there is considerable similarity of function, although different systems are used, and thus there might be a similar experience in terms of suffering. The treatment of these animals in the food industry and elsewhere might thus pose welfare problems.
... Does the encounter of stressors (predators, odors, noises, etc.) impact exploratory activity? A stress response is typically produced when individuals experience environmental conditions outside of their normal and/or safe perceptual range (Elwood, Barr, & Patterson, 2009). In vertebrates, the physiological stress response consists of an activation of the hypothalamus-pituitary-adrenocortical axis (Cabib & Puglisi-Allegra, 2012), which may lead to the release of glucocorticoid hormones such as cortisol and corticosterone. ...
... The consequences of glucocorticoids on exploratory activity depend on the species and the situation (Grønli et al., 2005;Harris, Zhou, Youngblood, Smagin, & Ryan, 1998;Pravosudov, 2003;Strekalova, Spanagel, Bartsch, Henn, & Gass, 2004). Invertebrates also react to environmental stressors, causing a physiological stress response that has common features with that observed in vertebrates (Elwood et al., 2009;Ottaviani & Franceschi, 1996;Stefano et al., 2002). In crustaceans, the hyperglycemic hormone is the physiological marker of a stress response; this hormone plays a role similar to cortisol and corticosterone. ...
... Although the existence of physiological stress responses in invertebrates is now a well-established fact, the question of whether the members of invertebrate species can experience conscious feelings related to these physiological stress responses remains controversial (Barron & Klein, 2016;Elwood et al., 2009;Mason, 2011;Mendl, Paul, & Chittka, 2011). In this study, I do not aim to enrich this debate one way or the other. ...
Terrestrial isopods (or woodlice), like the members of the other arthropod taxa, have a sophisticated nervous system that makes them sensitive to specific environmental factors. They can search for survival-related opportunities (e.g., approaching food sources or avoiding sunny areas). Two experiments examined how rotational stress could influence the propensity of common woodlice, Porcellio scaber to exhibit survival-related behaviors such as traveling and rearing up in a hostile environment. Experiment 1 assessed the behaviors of stressed and nonstressed woodlice exposed to a familiar or a novel environment without rewards. Experiment 2 assessed the effects of stress in woodlice given a free choice between a familiar and a novel environment without rewards. In the nonstressed individuals, the results showed a decrease in locomotor activity (habituation) and an increase in the time spent rearing up (sensitization) on the arena’s walls over time. In the stressed individuals, repeated rotation had a detrimental effect on the time spent rearing up, but locomotion was decreased only in the stressed individuals that were not preexposed to the test environment beforehand. In addition, immobilization periods—as a plausible indicator of stress—were longer in the absence of preexposure. It is suggested that preexposure had some antistress protective effects on habituated but not on sensitized, exploratory behaviors in woodlice.
... Sound: The supply of crustaceans should meet regulatory standards and public ethical expectations in terms of animal welfare, biosecurity, and traceability (and food authenticity), including fair treatment and management of workers (Wickins and Lee 2002). The ability of invertebrates, including crustaceans, to experience pain and stress has become increasingly studied ( Fig. 19.2) and is increasingly entering the public consciousness (Elwood et al. 2009, Horvath et al. 2013, Crustacean Compassion 2017. ...
... National animal welfare regulations, for example the EU (Council Regulation (EC) No. 1/ 2005 and UK Animal Welfare Act), apply to animals for live export, although in practice, this is probably rarely, if ever, applied to live crustaceans. Public awareness of crustacean welfare and the potential to experience negative stimuli is growing, which has ramifications for crustacean transport and fishery practices (Elwood et al. 2009). For scientific research at least, European member states recently adopted a directive (European Directive 2010/ 63/ EU) regarding the use of animals specifically to yield scientific data. ...
... Arthropods generally have an ability to detect unpleasant stimuli and respond via avoidance or escape reactions (termed nociception; Elwood et al. 2009). The capacity for a decapod to perceive pain, or a pain-like sensation (defined as an unpleasant sensory and emotional quality and its internal interpretation), is an ongoing debate. ...
*PUBLISHED AUGUST 2020*
https://global.oup.com/academic/product/fisheries-and-aquaculture-9780190865627?lang=en&cc=gb
Current production (ca. 14 million metric tonnes) and value (up to $60 billion) for crustaceans is significant and likely to increase further during the 21st century. Satisfactory management and handling of live crustaceans is important to safeguard the value, security, safety, and sustainability of wild-caught and aquaculture-sourced fisheries, and increasingly to foster improved welfare and public perception of both industries. Decapod crustaceans are frequently transported live and internationally over long distances, and experience anthropogenic stressors from point of capture to point of sale. Physical handling, emersion in air, and temperature fluctuations are key examples of stressors, which elicit progressive behavioral, physiological and immunological stress responses in crustaceans. Stress responses are initiated to return the individual to a state of homeostasis; if these fail, then physiological collapse, a loss of vitality and death will likely occur. There are several ways to mitigate against the impact of stressors, reduce associated stress responses, and thus maintain quantity (survival, weight) and quality (vitality, sensorial perception) of live crustaceans. These include improved fishing techniques, better handling and operating procedures, and the introduction of proven equipment and facilities during the supply chain. The action of stressors and effectiveness of potential mitigating strategies have been studied intensively via behavioral analysis, and hemolymph sampling to ascertain changes in metabolites and the immune system. Finally, improved handling and management includes global and ethical considerations, supported by relevant research, which may be achieved by adopting best practices and standards and by ensuring welfare and disease regulations.
... When they fire, they initiate a reflex by which the animal withdraws part or all of its body to avoid further noxious stimuli. Importantly for understanding the complexity of pain, the reflex does not necessarily involve the central nervous system or central processing and does not necessarily produce the emotional experience of pain [10]. Thus, simply noting that an animal avoids noxious stimuli does not enable pain to be inferred. ...
... For example, numerous studies on Drosophila have been key to our understanding the development and functioning of these nerve cells [11]. They have been much less studied in decapods, but they have been inferred from the behavioural responses of these animals and from examination of surface receptors [10]. Decapods respond to mechanical, thermal, and chemical stimuli [7,12], and receptors have been described that respond to those stimuli [7,13]. ...
... In vertebrates, it causes a cascade of hormonal changes that leads to the production of adrenal hormones (cortisol and corticosterone), which stimulate the conversion of glycogen to glucose used in the fight-or-flight response. In decapods, stress releases the crustacean hyperglycemic hormone (CHH), which has broadly similar effects to those adrenal hormones in vertebrates [10], or by releasing biogenic amines such as epinephrine and serotonin [38,39]. ...
Vast numbers of crustaceans are produced by aquaculture and caught in fisheries to meet the increasing demand for seafood and freshwater crustaceans. Simultaneously, the public is increasingly concerned about current methods employed in their handling and killing. Recent evidence has shown that decapod crustaceans probably have the capacity to suffer because they show responses consistent with pain and have a relatively complex cognitive capacity. For these reasons, they should receive protection. Despite the large numbers of crustaceans transported and slaughtered, legislation protecting their welfare, by using agreed, standardized methods, is lacking. We review various stunning and killing systems proposed for crustaceans, and assess welfare concerns. We suggest the use of methods least likely to cause suffering and call for the implementation of welfare guidelines covering the slaughter of these economically important animals.
... Generally, this effect is expressed with behaviors such as a lesser effort to avoid the sources of pain, as shown in snails (Kavaliers et al., 1983). Related to the similarity between the physiological changes associated to the experience of pain in vertebrates and invertebrates, we can also emphasize pupil dilatation, changes in blood and respiration flow rates, and stress or relative changes in the endocrine system (Elwood et al., 2009;Elwood, 2011). In the light of this evidence, some researchers have already claimed the use of analgesics and anesthetics in research with invertebrates (Lockwood, 1987(Lockwood, , 1988Crook & Walters, 2011). ...
... After one minute they are returned to the dark compartment. With only one trial, the crabs are unwilling to return to the illuminated compartment after 3 hours (Elwood et al., 2009). When they have undergone this process several times, the crabs display this behavior until up to 24 hours later. ...
... When they have undergone this process several times, the crabs display this behavior until up to 24 hours later. Similar investigations have been carried out with fruit flies (Yarali et al., 2008), cockroaches or ants (Broom, 2013), and lobsters (Elwood et al., 2009). The results of this research concerning memory and painavoidance learning provides solid reasons to conclude that, if we accept that vertebrates experience pain, the same must be concluded in the case of at least some invertebrates. ...
Invertebrate animals are usually seen as a kind of “aliens” which do not deserve any moral consideration. However, there is a growing amount of evidence indicating that many of them do have the capacity to experience pain. The same criteria that are usually applied in order to infer that vertebrates are sentient beings (behavioral response, learning capacity, memory, a certain specific neurophysiological structure…) lead to the idea that many invertebrates are sentient as well. Therefore, under the skeptical premise that we have no direct evidence of the experience of pain in vertebrates, we are forced to hold that it exists in both vertebrates and invertebrates.
... A stronger argument for a more inclusive ethics than the mere existence of advanced cognition (Vallortigara 2017(Vallortigara , 2020 is provided by the handful of recent studies investigating metacognition (Perry & Barron 2013), emotion-like states (Perry et al. 2016; but cf. Baracchi et al. 2017), sentience ) and pain (Elwood et al. 2009;Gherardi 2009;Elwood 2011) in Pancrustacea. Empirical studies and cognitive theorists have begun to support the existence of very basic forms of consciousness, such as subjective experience in invertebrates. ...
... There is evidence that positive or negative emotions can be induced in some invertebrates and that these affect their judgment (Bateson et al. 2011;Perry & Barron 2013;Fossat et al. 2014;Gibson et al. 2015). Crustaceans may feel pain (Elwood et al. 2009;Gherardi 2009;Elwood 2011), and the behavioral and physiological responses of crayfish to electric shocks are analogous to those of mammals, suggesting that they might experience fear (Fossat et al. 2014). ...
... Humans are not the only ones to face stress. Although this may seem trivial from today's perspective, soil invertebrates such as isopods may also suffer from stress (Elwood et al. 2009). 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). ...
... Just like vertebrates, invertebrates respond to stress caused by changes in the environment with a stress reaction. Isopods secrete substances into the haemolymph which are similar to glucocorticoids that can be found in vertebrates (Elwood et al. 2009). Stress can also shorten the maternal care period of the clutch (Kight and Nevo 2004). ...
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.
... Invertebrates such as shrimps, clams, squids, locusts, termites, grasshoppers, and beetle grubs, as well as honey from bees serve as a major source of human food worldwide [40] . For instance, research utilizing invertebrates include everything from field research on biodiversity and conservation to use as laboratory models for the biological systems of other animals, including humans [40,43] . Public concern is also economically motivated. ...
... For example, the increased occurrence of colony-collapse disorder in honey bees has led to increased research into bee health and welfare, because of their importance in producing honey and pollinating crops [42] . But the most striking example of the public's increased concern about invertebrate welfare is the growing dialogue on the welfare of decapods crustaceans during a live cooking [43,44] . Map ...
The present research was conducted to explore the vertebrate and invertebrate fauna in Khurum dam and Muhabbat Khel dam of district Karak, Khyber Pakhtunkhwa province of Pakistan during the period from April 2016 to December 2016. The Khurum dam and Muhabbat Khel dam having all the vertebrates including fishes, amphibians, reptiles, birds and mammals. Fishes of both dams include Cyprinus carpio, Crossocheilus diplochielus, Ctenopharyngodon idella, Salmophasia bacaila, Aspidoparia morar Ompok pabda Labeo rohita, Cirrhinus cirrhosus, Hypophthalmichthys molitrix. The family Cyprinidae is dominant in both dams. The Amphibians of both dams include Rana tigrina, Euphlyctis cyanophlyctis, Duttaphrynus melanostictus and Rana tigrina. The Reptiles of Khurum dam are Chamaeleo zeylanicus, Saara hardwickii, Xantusia vigilis, Lampropeltis getula and in Muhabbat Khel dam Xantusia vigilis, Lampropeltis getula are present. In Khurum dam nine species of birds are present, which is following
Passer domesticus, Acridotheris tristis, Anas crecca, Perdix Perdix, P. cristatus, Numida meleagris, Grus grus, Pycnonotus barbatus, Upupa epops. While in Muhabbat khel dam Passer domesticus, Acridotheris tristis, Anas crecca, Buteo jamaicensis, Cairina moschata, Dicrurus adsimilis. The family Bovidae of mammals is more abundant in both dams. The invertebrates found in Khurum dam are Sympetrum flaveolum, Pandinus imperator, Pterostichus melanarius, Anex junius, Solenopsis invicta, Hirudo medicinalis and Sceliphron caementarium Vespa velutina, Hirudo medicinalis, Pandinus imperator are present in Muhabbat Khel dam. So from the present study, it may be concluded that Khurum and Muhabbat Khel dams are very suitable for the growth of both vertebrates and invertebrates. Hence our present study will provide useful information about the diversity of vertebrates and invertebrates of the both dams that could be later valuable in systematic and conservation.
... Cunningham et al. (2021b) also observed alterations of various aspects of defence and attack with regard to 'rapping contests' (which is the acquisition of an already occupied shell from another hermit crab) in Pagurus bernhardus individuals exposed to microplastics. Changes in behavioural patterns due to toxicants are thus linked to physiological alterations as detailed in the previous sections and can manifest as stressful or painful circumstances in crustaceans (Elwood et al., 2009;Hebel et al., 1997). Thus, microplastics could affect behaviours such as foraging, predation, mating, fighting and even swimming which could lead to a weakened state of the animal (Barboza et al., 2018;Crooks et al., 2019). ...
... In spite of all the information available on microplastics in Decapods, a number of other tests/studies could be conducted to fully understand microplastic toxicity. For example, the effects of microplastics on the crustacean hyperglycemic hormone (CCH), which is the equivalent of the vertebrate stress hormone cortisol and corticosterone (Elwood et al., 2009) have not been evaluated. This hormone has been used as an indicator of stress in Decapod crustaceans Guo et al., 2021;Lorenzon et al., 2004). ...
The presence of microplastics in the aquatic environment poses a serious threat not only to aquatic organisms but also to human beings that consume them. The uptake and effects of microplastics have been studied in almost all groups of aquatic organisms. This review details the different aspects of microplastics exposure in an ecologically and economically important group of crustaceans, the Decapods. A majority of Decapod crustaceans such as prawns, shrimp, crabs, lobsters and crayfish are consumed as seafood and play important roles in food chains and food webs. Numerous studies are available on the accumulation of microplastics in tissues such as the gills, hepatopancreas and gastrointestinal tract in these organisms. Experimental studies have also highlighted the toxic effects of microplastics such as oxidative stress, immunotoxicity and reproductive and developmental toxicity in them. This review also summarizes the ecological impacts and implications in human beings as well as lacunae with regard to microplastic uptake in Decapods.
... Invertebrates such as shrimps, clams, squids, locusts, termites, grasshoppers, and beetle grubs, as well as honey from bees serve as a major source of human food worldwide [40] . For instance, research utilizing invertebrates include everything from field research on biodiversity and conservation to use as laboratory models for the biological systems of other animals, including humans [40,43] . Public concern is also economically motivated. ...
... For example, the increased occurrence of colony-collapse disorder in honey bees has led to increased research into bee health and welfare, because of their importance in producing honey and pollinating crops [42] . But the most striking example of the public's increased concern about invertebrate welfare is the growing dialogue on the welfare of decapods crustaceans during a live cooking [43,44] . Map ...
The present research was conducted to explore the vertebrate and invertebrate fauna in Khurum dam and Muhabbat Khel dam of district Karak, Khyber Pakhtunkhwa province of Pakistan during the period from April 2016 to December 2016. The Khurum dam and Muhabbat Khel dam having all the vertebrates including fishes, amphibians, reptiles, birds and mammals. Fishes of both dams include Cyprinus carpio, Crossocheilus diplochielus, Ctenopharyngodon idella, Salmophasia bacaila, Aspidoparia morar Ompok pabda Labeo rohita, Cirrhinus cirrhosus, Hypophthalmichthys molitrix. The family Cyprinidae is dominant in both dams. The Amphibians of both dams include Rana tigrina, Euphlyctis cyanophlyctis, Duttaphrynus melanostictus and Rana tigrina. The Reptiles of Khurum dam are Chamaeleo zeylanicus, Saara hardwickii, Xantusia vigilis Lampropeltis getula and in Muhabbat Khel dam Xantusia vigilis Lampropeltis getula are present. In Khurum dam nine species of birds are present, which is following Passer domesticus, Acridotheris tristis, Anas crecca, Perdix Perdix, P. cristatus, Numida meleagris, Grus grus, Pycnonotus barbatus, Upupa epops. While in Muhabbat khel dam Passer domesticus, Acridotheris tristis, Anas crecca, Buteo jamaicensis, Cairina moschata, Dicrurus adsimilis. The family Bovidae of mammals is more abundant in both dams. The invertebrates found in Khurum dam are Sympetrum flaveolum, Pandinus imperator, Pterostichus melanarius, Anex junius, Solenopsis invicta, Hirudo medicinalis and Sceliphron caementarium Vespa velutina, Hirudo medicinalis, Pandinus imperator are present in Muhabbat Khel dam. So from the present study, it may be concluded that Khurum and Muhabbat Khel dams are very suitable for the growth of both vertebrates and invertebrates. Hence our present study will provide useful information about the diversity of vertebrates and invertebrates of the both dams that could be later valuable in systematic and conservation.
... An approach in the future which may be beneficial would be to obtain as much hemolymph as possible and lyophilize it and resuspend in a smaller volume to concentrate the compounds or to make use of mass spectrometry-based approaches to screen peptides as well [71]. Even the handling of the animals to draw hemolymph samples may result in the animals altering the levels of the compound to be measured [14,[72][73][74][75]. Both serotonin and octopamine can increase central neural activity in crustaceans and insects and in some cases synaptic transmission at neuromuscular junctions. ...
Stunning of edible crustaceans to reduce sensory perception prior and during slaughter is an important topic in animal welfare. The purpose of this project was to determine how neural circuits were affected during stunning by examining the physiological function of neural circuits. The central nervous system circuit to a cardiac or skeletal muscle response was examined. Three commercially important crustacean species were utilized for stunning by immersion in an ice slurry below 4 °C and by electrocution; both practices are used in the seafood industry. The blue crab (Callinectes sapidus), the red swamp crayfish (Procambarus clarkii), and the whiteleg shrimp (Litopenaeus vannamei) responded differently to stunning by cold and electric shock. Immersion in ice slurry induced sedation within seconds in crayfish and shrimp but not crabs and cardiac function was reduced fastest in shrimp. However, crabs could retain a functional neural circuit over the same time when shrimp and crayfish were nonresponsive. An electroshock of 10 s paralyzed all three species and subsequently decreased heart rate within 1 min and then heart rate increased but resulted in irregularity over time. Further research is needed to study a state of responsiveness by these methods.
... Humans tend to perceive animals similar to us, such as other mammals, as possessing higher cognitive abilities (Eddy, Gallup, & Povinelli, 1993), and feel greater empathy toward them (Harrison & Hall, 2010;Hills, 1995;Westbury & Neumann, 2008). Those seen as dissimilar to us such as invertebrates tend to be perceived as not having a mind or identity; as such, there is a lack of concern for their treatment (Elwood, Barr, & Patterson, 2009;Horvath, Angeletti, Nascetti, & Carere, 2013;Kellert, 1993). Humans may be particularly drawn to animals such as dogs, especially puppies, because they share features with human infants such as big eyes, large foreheads, and soft contours (Amiot, Bastian, & Martens, 2016). ...
Despite the widespread belief among the public and an increasing number of law enforcement personnel that individuals who harm animals often harm other people, the subject of animal maltreatment has received little attention from behavioral scientists. Advances in comparative neuroanatomy have highlighted the ability of animals to feel physical and emotional pain, including complex psychological reactions to traumatic events. These advances, and recent studies (however sparse) that support the notion that perpetrators of crimes against animals often commit other crimes, have arguably created an ethical and practical imperative for behavioral scientists to undertake a serious examination of animal maltreatment and potential mechanisms for responding to it. In addition, the close and complex relationships many Americans have with animals and the advancements in animal protection law in the past two decades necessitate expertise on the part of forensic psychologists and psychiatrists, who will increasingly be called upon to evaluate animal maltreatment offenders and consult on related policy and legislation.
... Intermediate individuals should follow the sequence of behaviors such as described in Fig. 1. Testing these predictions requires to measure and compare concentrations of the hyperglycemic hormonethe equivalent of corticosterone in crustaceans (e.g., Elwood et al., 2009)in the hemolymph in these three categories of individuals. Establishing a positive correlation between physiological stress and behavioral reactions predicted by the present model could be useful to study the effects of "temperament" on processes such as decision-making, foraging, and social interactions in invertebrates. ...
Woodlice placed in an unknown experimental enclosure typically run (horizontal exploration) and rear up on the enclosure's walls (vertical exploration). Previous findings with Porcellio scaber indicate that these two behaviors have an opposite temporal distribution and show differential sensitivity to rotation-induced physiological stress. It is argued that the dual-process theory of habituation and sensitization can serve as a basis to account for horizontal and vertical exploratory activities in woodlice. A model is presented. This model could help identify individual variability in “temperament” and to isolate its effects in various behavioral tasks in woodlice and perhaps other invertebrate species.
... Lobster was chosen in order to explore the effect of giving information about the killing of an animal and because we suspected that, in line with the Liao and Meskin (2018) prediction, positive ethical information with a trace might have a negative effect on expectations in this case. Several studies indicate that crustaceans are able to feel pain (Elwood et al., 2009;Elwood, 2012) leading to controversy about the way in which lobsters are killed before cooking. For lobster we created only positive vignettes (control, positive/no trace -sustainable, positive/trace -humanely killed). ...
It has been suggested that information about ethically relevant factors in production can affect both the expectation and experience of foods. However, evidence on these issues is inconsistent. We begin by discussing recent philosophical work on the interaction of ethical and aesthetic values in the domain of food, work which is inspired by a similar debate about art. Some philosophers have suggested that ethical factors in production that leave a ‘trace’ on a product, i.e., make a perceivable difference to it, will affect the aesthetic quality of the food. There has also been the suggestion that these sorts of ethical/aesthetic interactions may vary across different kinds of food. In two studies we examined the expected experience and the actual experience of eating various foods, when participants had been given ethically relevant information about those foods. We examined people’s ethical values and the effect that had on the ratings. We found strong evidence to suggest that ethically relevant information affects expected experience of food and that the valence of the information is a significant factor. We found an effect of ethical values on expectations of food. Most notably, we found evidence that suggests that ‘trace’ may be a relevant factor mediating the effect of ethically relevant information on expectations and experience of food. Future research should further explore the factor of trace, look at the effect of ethical information in a wider range of foods, and investigate these phenomena in distinct populations.
... La importancia de la configuración de representaciones subjetivas actuales en los animales se puede apreciar asimismo en la capacidad para evitar las fuentes de dolor en el futuro. Tal es el caso, entre otros muchos, de los cangrejos que reniegan de entrar en un compartimento iluminado desde uno oscuro tras establecer un vínculo entre el dolor experimentado en el primero con electroshocks (Elwood et al., 2009) 4. conclusIones Con la finalidad de superar una de las críticas más usuales a la HOT, aquella que presupone intuitivamente que hay animales no humanos con estados conscientes, sus defensores optarán por dos posibles posiciones. En primer lugar, abanderando una HOT de tipo disposicional, Peter Carruthers niega que este pueda ser considerado un problema para las HOT. ...
... It may also have arisen from an understanding that natural selection might have shaped emotions more for survival than for prosperity, there being many more 'threats' than 'treats' in the environment [134]. Indeed, pain and other putative aversive stimuli have been major foci of affect-centred research designed to explore the question of sentience in less-studied taxa including fishes [118,119,135], as well as cephalopods [56,[128][129][130], decapods [136][137][138][139][140] and other invertebrates [50]. ...
The focus of this opinion is on the key features of sentience in animals which can experience different states of welfare, encapsulated by the new term ‘welfare-aligned sentience’. This term is intended to exclude potential forms of sentience that do not enable animals in some taxa to have the subjective experiences which underlie different welfare states. As the scientific understanding of key features of sentience has increased markedly during the last 10 to 15 years, a major purpose here is to provide up-to-date information regarding those features. Eleven interconnected statements about sentience-associated body functions and behaviour are therefore presented and explained briefly. These statements are sequenced to provide progressively more information about key scientifically-supported attributes of welfare-aligned sentience, leading, in their entirety, to a more comprehensive understanding of those attributes. They are as follows: (1) Internal structure–function interactions and integration are the foundations of sentience; (2) animals posess a capacity to respond behaviourally to a range of sensory inputs; (3) the more sophisticated nervous systems can generate subjective experiences, that is, affects; (4) sentience means that animals perceive or experience different affects consciously; (5) within a species, the stage of neurobiological development is significant; (6) during development the onset of cortically-based consciousness is accompanied by cognitively-enhanced capacities to respond behaviourally to unpredictable postnatal environments; (7) sentience includes capacities to communicate with others and to interact with the environment; (8) sentience incorporates experiences of negative and positive affects; (9) negative and positive affective experiences ‘matter’ to animals for various reasons; (10) acknowledged obstacles inherent in anthropomorphism are largely circumvented by new scientific knowledge, but caution is still required; and (11) there is increasing evidence for sentience among a wider range of invertebrates. The science-based explanations of these statements provide the foundation for a brief definition of ‘welfare-aligned sentience’, which is offered for consideration. Finally, it is recommended that when assessing key features of sentience the same emphasis should be given to positive and negative affective experiences in the context of their roles in, or potential impacts on, animal welfare.
... However, given our uncertainty about which animals possess a capacity for sentience and thus our growing discomfort about excluding species that might meet the 'club membership criteria' [67,68], do Compassionate Conservationists give all animals the benefit of the doubt? This is unclear. ...
Compassionate Conservation and Conservation Welfare are two disciplines whose practitioners advocate consideration of individual wild animals within conservation practice and policy. However, they are not, as is sometimes suggested, the same. Compassionate Conservation and Conservation Welfare are based on different underpinning ethics, which sometimes leads to conflicting views about the kinds of conservation activities and decisions that are acceptable. Key differences between the disciplines appear to relate to their views about which wild animals can experience harms, the kinds of harms they can experience and how we can know about and confidently evidence those harms. Conservation Welfare scientists seek to engage with conservation scientists with the aim of facilitating ongoing incremental improvements in all aspects of conservation, i.e., minimizing harms to animals. In contrast, it is currently unclear how the tenets of Compassionate Conservation can be used to guide decision-making in complex or novel situations. Thus, Conservation Welfare may offer modern conservationists a more palatable approach to integrating evidence-based consideration of individual sentient animals into conservation practice and policy.
... Captivity with restricted movement in a small container gives stress to the captive animals of a variety of species (reviewed in Morgan and Tromborg, 2007;McGaw and Nancollas, 2018 and long-term captivity does not mitigate the stress response (de Assis et al., 2015d). Stress causes appetite reduction and reduced food intake in crustaceans and fish (Bonga, 1997;Teegarden and Bale, 2008;Conde-Sieira et al., 2008;Elwood et al., 2009;Wale et al., 2013;Conde-Sieira et al., 2018). Islam et al. (2018) reported that the weight gain was significantly lower in S. tranquebarica reared individually in indoor compartments compared with those communally reared in an outdoor tank. ...
... All non-supplemented gammarids showed a depletion of circulating carotenoids in their haemolymph. Maintenance under laboratory conditions is stressful for crustaceans [55], and stress can deplete carotenoid stocks [56]. Nonsupplemented gammarids may have therefore consumed the carotenoids they had previously stored from their natural habitat, to cope with the stress induced by laboratory maintenance. ...
Carotenoids are diverse lipophilic natural pigments which are stored in variable amounts by animals. Given the multiple biological functions of carotenoids, such variation may have strong implications in evolutionary biology. Crustaceans such as Gammarus amphipods store large amounts of these pigments and inter-population variation occurs. While differences in parasite selective pressure have been proposed to explain this variation, the contribution of other factors such as genetic differences in the gammarid ability to assimilate and/or store pigments, and the environmental availability of carotenoids cannot be dismissed. This study investigates the relative contributions of the gammarid genotype and of the environmental availability of carotenoids in the natural variability in carotenoid storage. It further explores the link of this natural variability in carotenoid storage with major crustacean immune parameters. We addressed these aspects using the cryptic diversity in the amphipod crustacean Gammarus fossarum and a diet supplementation protocol in the laboratory. Our results suggest that natural variation in G. fossarum storage of dietary carotenoids results from both the availability of the pigments in the environment and the genetically-based ability of the gammarids to assimilate and/or store them, which is associated to levels of stimulation of cellular immune defences. While our results may support the hypothesis that carotenoids storage in this crustacean may evolve in response to parasitic pressure, a better understanding of the specific roles of this large pigment storage in the crustacean physiology is needed.
... This hormone is secreted from the sinus gland (Fanjul-Moles, 2006) in response to stressful stimuli in crustaceans (Chang et al., 2005). Moreover, this hormone has been described as the crustacean equivalent of cortisol and corticosterone (Elwood et al., 2009). ...
Stressors are omnipresent in the environment and trigger specific physiological and/or behavioural responses that remain relatively less known in invertebrates. Among the parameters used to quantify the impact of stress on physiology, the circulating level of glucose is commonly used in aquatic crustacean species. Terrestrial isopods are small crustaceans commonly used as bioindicators of soil quality; however, their response to environmental stressors remains poorly documented. In laboratory conditions, we investigated how different stressors influence the physiological response of two terrestrial isopod species. Thus, we exposed Armadillidium vulgare and Porcellio dilatatus to a series of both acute (physical) and chronic (temperature, social isolation, and exposure to herbicide) stressors that mimic potentially stressful situations encountered in their environment. Our results revealed that, for both species, glycaemia is not impacted by thermic shock (1 h at 4 °C), mechanical disturbances (1 min of shaking or upside-down motion) or social isolation (4 weeks) at the population level. Nevertheless, we observed a significantly higher sensitivity in male P. dilatatus exposed to upside-down movements and in males of both species exposed to social isolation. Acute (96 h) and chronic (21 days) exposure to glyphosate (1.8–2.5 kg.ha−1) did not impact glycaemia levels in A. vulgare. However, at both tested doses, individuals exposed to glyphosate for 25 days and subjected to an additional stressor (haemolymph sampling at 96 h) had significantly higher glycaemia in comparison to their control. Survival was also impacted by the joint application of chronic glyphosate exposure and intermediate haemolymph sampling. We conclude that glucose is a potentially good indicator to study the stress response of terrestrial isopods. Additional studies for this parameter, combined with other physiological indicators, are needed to better characterize this response.
... Number of females (Nf) is indicated in Table 2 stress (Meyer et al. 1992). The crustacean hyperglycemia hormone (CHH) has been proposed as the stress hormone of crustaceans (Chang et al. 1999;Elwood et al. 2009); its multifunctional role, including some effects on the ovary of some crustaceans, has been reported (De Kleijn and Van Herp, 1998;Fanjul-Moles 2006). In the current study, the significant chronic increase of glycemia is expected to be caused by augmented and sustained levels of circulating CHH. ...
Adult females of the estuarine crab Neohelice granulata were exposed to the glyphosate formulation Roundup Ultramax® during the entire 3-month pre-reproductive period. At the end of the assay, a significant higher increment of glycemia was noted at both glyphosate concentrations assayed (0.01 and 0.2 mg/L, acid equivalent). Although no differences were observed in the gonadosomatic index, a significantly higher proportion of reabsorbed vitellogenic oocyte was observed at the highest glyphosate concentration, together with a significant decrease of vitellogenin content in the ovary. In addition, some in vitro assays were carried out by co-incubating small pieces of ovary with or without the addition of Roundup; at both concentrations tested (same as those used in vivo), a decrease in the ovarian vitellogenin content was observed, whereas the ovarian protein synthesis was significantly inhibited by glyphosate at 0.2 mg/L in the Roundup formulation used.
... Different systems from those of vertebrates, similar functions, possibly similar experience of suffering (Elwood et al. 2009) ...
The aim of this paper is to take normative aspects of animal welfare in corporate practice from a blind spot into the spotlight, and thus connect the fields of business ethics and animal ethics. Using insights from business ethics and animal ethics, it argues that companies have a strong responsibility towards animals. Its rationale is that animals have a moral status, that moral actors have the moral obligation to take the interests of animals into account and thus, that as moral actors, companies should take the interests of animals into account, more specifically their current and future welfare. Based on this corporate responsibility, categories of corporate impact on animals in terms of welfare and longevity are offered, including normative implications for each of them. The article concludes with managerial implications for several business sectors, including the most animal-consuming and animal-welfare-threatening industry: the food sector. Welfare issues are discussed, including the issue of killing for food production.
... There are no minimal animal care requirements for decapods in the European legislation [47]. They have long been regarded as not being sentient and unable to experience pain or suffering because they were thought to respond to noxious stimuli purely by nociceptive reflex [48,49]. ...
Decapod crustaceans are widely used as experimental models, due to their biology, their sensitivity to pollutants and/or their convenience of collection and use. Decapods have been viewed as being non-sentient, and are not covered by current legislation from the European Parliament. However, recent studies suggest it is likely that they experience pain and may have the capacity to suffer. Accordingly, there is ethical concern regarding their continued use in research in the absence of protective measures. We argue that their welfare should be taken into account and included in ethical review processes that include the assessment of welfare and the minimization or alleviation of potential pain. We review the current use of these animals in research and the recent experiments that suggest sentience in this group. We also review recent changes in the views of scientists, veterinary scientists and animal charity groups, and their conclusion that these animals are likely to be sentient, and that changes in legislation are needed to protect them. A precautionary approach should be adopted to safeguard these animals from possible pain and suffering. Finally, we recommend that decapods be included in the European legislation concerning the welfare of animals used in experimentation. View Full-Text
... As with fish, crustaceans, are thought to encounter uncomfortable experiences during their capture and death, particularly during their live storage and transport. Similar techniques, such as electric stunning prior to processing have been used to reduce unnecessary abuse to their welfare (Elwood et al. 2009;Neil 2010;Roth and Oines 2010;Jennings et al. 2016). ...
Food fraud is an intentional act for economic gain. It poses a risk to food integrity, the economy, public health and consumers’ ethics. Seafood is one commodity which has endured extensive fraudulent activity owing to its increasing consumer demand, resource limitations, high value and complex supply chains. It is essential that these fraudulent opportunities are revealed, the risk is evaluated and countermeasures for mitigation are assigned. This can be achieved through mapping of the seafood supply chains and identifying the vulnerability analysis critical control points (VACCP), which can be exposed, infiltrated and exploited for fraudulent activity. This research systematically maps the seafood supply chain for three key commodities: finfish, shellfish and crustaceans in the United Kingdom. Each chain is comprised of multiple stakeholders across numerous countries producing a diverse range of products distributed globally. For each supply chain the prospect of fraud, with reference to species substitution, fishery substitution, illegal, unreported and unregulated substitution, species adulteration, chain of custody abuse, catch method fraud, undeclared product extension, modern day slavery and animal welfare, has been identified and evaluated. This mapping of the fraudulent opportunities within the supply chains provides a foundation to rank known and emerging risks and to develop a proactive mitigation plan which assigns control measures and responsibility where vulnerabilities exist. Further intelligence gathering and management of VACCPs of the seafood supply chains may deter currently unknown or unexposed fraudulent opportunities.
... Shrimp trials and experiments in this study were approved by the Institutional Animal Care and Use Committee of the National Center for Genetic Engineering and Biotechnology, Thailand (BT-Animal 28/2560). All experiments were performed in accordance with Animal Research: Reporting of In Vivo Experiments (ARRIVE) and conformed with international and national legal and ethical requirements [28,29]. ...
Cyclooxygenase (COX) is a two-step enzyme that converts arachidonic acid into prostaglandin H2, a labile intermediate used in the production of prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α). In vertebrates and corals, COX must be N-glycosylated on at least two asparagine residues in the N-(X)-S/T motif to be catalytically active. Although COX glycosylation requirement is well-characterized in many species, whether crustacean COXs require N-glycosylation for their enzymatic function have not been investigated. In this study, a 1,842-base pair cox gene was obtained from ovarian cDNA of the black tiger shrimp Penaeus monodon. Sequence analysis revealed that essential catalytic residues and putative catalytic domains of P. monodon COX (PmCOX) were well-conserved in relation to other vertebrate and crustacean COXs. Expression of PmCOX in 293T cells increased levels of secreted PGE2 and PGF2α up to 60- and 77-fold, respectively, compared to control cells. Incubation of purified PmCOX with endoglycosidase H, which cleaves oligosaccharides from N-linked glycoproteins, reduced the molecular mass of PmCOX. Similarly, addition of tunicamycin, which inhibits N-linked glycosylation, in PmCOX-expressing cells resulted in PmCOX protein with lower molecular mass than those obtained from untreated cells, suggesting that PmCOX was N-glycosylated. Three potential glycosylation sites of PmCOX were identified at N79, N170 and N424. Mutational analysis revealed that although all three residues were glycosylated, only mutations at N170 and N424 completely abolished catalytic function. Inhibition of COX activity by ibuprofen treatment also decreased the levels of PGE2 in shrimp haemolymph. This study not only establishes the presence of the COX enzyme in penaeid shrimp, but also reveals that N-glycosylation sites are highly conserved and required for COX function in crustaceans.
... Investigation of the potential stress of handling decapod crustaceans during experimentation will likely become more pertinent in the coming years. Recently, there has been debate regarding if/how decapod crustaceans experience pain and stress, and there is continuing discussion about re-classifying them as 'animals,' thereby requiring animal welfare protocols for scientific experiments (Elwood et al. 2009;Stevens et al. 2016;Weineck et al. 2018;Diggles 2019;Drinkwater et al. 2019;Elwood 2019). ...
Stress due to handling is often an unavoidable feature of experimental investigations. In some cases, appropriate settling times are not considered, and as such, physiological responses caused by handling may become additive with those of experimental treatments. This study investigated the effect of different handling procedures on the acute physiological responses of green shore crab (Carcinus maenas). Handling, such as would occur during transport around a research facility or transfer during experimental procedure, was designated as light (10 min emersion) or severe (10 min emersion with shaking). Oxygen consumption (MO2) and haemolymph glucose and haemolymph L-lactate concentrations were elevated post-handling, the magnitude of the change related to the severity of handling stress. Glucose and L-lactate concentrations peaked within 1 h and returned to basal levels within 6 h, but MO2 remained elevated for 10 h, reflecting the additional energy required to oxidize L-lactate and replenish energy reserves. Differences between light and severe handling treatments showed that vibration (shaking) was a major contributor to the stress response, rather than the experimental emersion. This was confirmed in a second experiment where crabs were handled without emersion, and MO2 remained elevated for 14 h. In this experiment, the most pronounced increase in MO2 and metabolic parameters occurred in crabs that were physically touched and moved rapidly from the holding to experimental tanks. Here the touch, as well as vibration and visual stimuli, provoked a fight-flight response in the crabs. Stress responses were also evident in crabs gently transferred by containers. The fact that transferring crabs with no physical touching and minimal visual and vibrational stimuli still evoked a stress response, albeit less pronounced, supports a recommendation that crustaceans should be left to settle in the apparatus for at least 12 h after handling before experimental procedures are initiated.
... (Araneda, P erez & Gasca-Leyva, 2008;Otoshi et al., 2006). Stress can have adverse effects on a number of important functions in animals (Elwood, Barr & Patterson, 2009), resulting in hole performance alterations including growth and disease resistance (Eissa & Wang, 2014). For example, shrimp reared at high densities exhibited decreased resistance against pathogens as evidenced by reductions in immune parameters together with decreased expression levels of immune-related proteins (Lin et al., 2015). ...
We investigated whether the positive impacts of artificial substrates on shrimp performance are altered in any way by their format or mode of fixation in the tanks. To examine this question, substrates were fixed vertically in the water column in three different configurations: SCF treatment (Substrate Completely Fixed), SPF treatment (Substrate Partially Fixed) and SFF (Substrate in Frond Format). Another treatment received no substrate and served as control (WS = Without Substrate). The shrimp were cultured for 38 days in intensive biofloc culture tanks at a stocking density of 1,125 shrimp m−3. In general, water quality variables were similar among treatments and remained within the appropriate range for shrimp culture. The final biomass was higher (8.5 kg m−3) and the feed conversion ratio (FCR) lower (1.6) in all tanks with substrates when compared with the WS treatment tanks (final biomass = 6.3 kg m−3 and FCR = 3.1). However, only shrimp from the SCF and SPF treatments had a higher survival rate (>95.0%) compared to those in WS tanks (75.9%), which was statistically similar to the SFF treatment (88.0%). These results show that substrate format and its mode of fixation in tanks can alter shrimp performance. In well-aerated intensive tanks, substrates in frond format are constantly pushed to the tank surface, making it difficult for shrimp to adhere to the screens. In such situation, the extra surface provided by the substrates is not always available to the shrimp, a fact that minimizes the positive effects of substrate.
... However, studies have largely been limited to those on vertebrates, and few studies have focused on behavioral plasticity in response to threatening experiences in invertebrates, including crustaceans. A number of studies have shown that crustaceans demonstrate fearful/anxiety-like responses to aversive stimuli and situation (reviewed in Elwood et al. 2009;Fossat et al. 2014;Perrot-Minnot et al. 2017). For instance, crabs (Chasmagnathus granulatus) presented with a novel stimulus, such as a moving shadow, respond by escape running (i.e., fearful response), and this escape response is reduced by morphine injection (Maldonado et al., 1989). ...
Behavioral variation in animals is often influenced by experience. Previous studies have found that daily threatening experiences can enhance fear- and anxiety-like behaviors in some vertebrates. However, it is unclear whether the change in fear/anxiety behavior occurs in invertebrates. The present study investigated whether fear/anxiety behavior could be affected by a net-chasing treatment in two shrimp species (Neocaridina denticulata ssp. and Palaemon pacificus). The net-chasing treatment was repeated for 8 days to simulate daily predator experiences, and behavioral tests (open-field, shelter-seeking, and escape-response tests) were conducted on the day following the last day of treatment. Net-chased N. denticulata ssp. displayed a tendency to remain near a wall compared with the control in the open-field test, whereas net-chased P. pacificus shrimps demonstrated greater escape behavior compared with the control in the escape-response test. These results suggest that fear/anxiety behavior for both shrimp species can be affected by the net-chasing treatment, although the pattern of behavioral change differed between the two species. The findings suggest that daily threatening experiences change the behavior of shrimp and cause them to select a regular avoidance strategy when they encounter risks and unknown situations.
... This is not unique to insects, as similar controversies exist for reptiles, crustaceans and fish (e. g. Braithwaite and Droege, 2016;Elwood et al., 2009;Lambert et al., 2019). ...
Globally, there is increasing pressure to find solutions for feeding the growing human population. One of the proposed answers to this problem is to farm edible insects, both for human consumption and as feed for domesticated livestock. But what do we know about these miniature livestock? Are they capable of suffering, and if so, what does this mean for this new and growing industry? Here, we review a fraction of what is currently known about insect sentience and cognition, by focusing on a portion of the published scientific literature over the past 31 years (1990-2020). Specifically, our review aimed to (1) assess the extent to which insect sentience and cognition featured in a selection of the scientific literature published between 1990-2020, (2) assess which aspects have been studied, and in which insect taxa, and (3) identify the insect species currently being promoted in policy for farming, and the reasons why edible insects are now on the global policy agenda. We found evidence that many species of insects, across a broad range of taxonomic Orders, are assumed and/or confirmed to be capable of a range of cognitive abilities, and that there is reason to believe that some species may also feel important emotional states such as stress. The market for insects as feed and food is set to become a booming industry in the future, yet our review highlights how we still know very little about the minds of insects and their capacity to suffer in farming systems. We hope that our findings will stimulate additional research and subsequent policy development relating to how insects are farmed in the future, particularly in the context of mitigating any potential negative animal welfare impacts.
... For example, agitated honeybees show a 'pessimistic' bias when they are exposed to an ambiguous CS (odour) that predicts both reward and punishment (Bateson, Desire, Gartside, & Wright, 2011), a phenomenon possibly related to the 'optimistic' bias exhibited by rats, pigs, and starlings reared in an enriched, stress-free environment (Brydges, Leach, Nicol, Wright, & Bateson, 2011;Douglas, Bateson, Walsh, Bédué, & Edwards, 2012;Matheson, Asher, & Bateson, 2008; for an evolutionary approach to cognitive biases, see D. D. P. Marshall, Trimmer, Houston, & McNamara, 2013;von Hippel & Trivers, 2011). Also, because some brain structures and neurotransmitters appear to control the same processes across phyla (e.g., Adamo & Baker, 2011;Alcaro, Panksepp, & Huber, 2011;Barron, Søvik, & Cornish, 2010;Perry & Barron, 2013;Strausfeld & Hirth, 2013), invertebrates can exhibit comparable reactions-such as fear and stress responses-in many situations (Elwood, Barr, & Patterson, 2009;Ottaviani & Franceschi, 1996;Stefano et al. 2002). In particular, Strausfeld and Hirth (2013) found homology between central complex (insects) and basal ganglia, which are known to play a determining role in reward and uncertainty processing in vertebrates (e.g., Berridge, 2007;Fiorillo, Tobler, & Schultz, 2003). ...
Bees tend to avoid or to show indifference to uncertain (“risky”) relative to certain (“safe”) food rewards, whether in nectar volume or in nectar concentration. The unattractiveness of uncertain food rewards is also sometimes independent of the energy budget of bees. This pattern of responses seems to differ from that observed in mammals and birds, which may exhibit a strong preference for the uncertainty over the certainty of food delivery on a given trial in dual-choice tasks. Upon analysis of the conditions that determine preference and aversion for uncertain food rewards in “higher” vertebrates, I attempt to demonstrate that bees react to uncertainty in a similar way. It is argued that, because of their social organization and of the type of resources they seek, bees are essentially exposed to situations in which “higher” vertebrates find reward uncertainty unattractive as well. The nature of their representation of food distribution is discussed, and it is suggested that scout bees may differ from recruits with respect to uncertainty processing.
Chinese grass shrimp, Palaemonetes sinensis (Sollaud, 1911), is an economically important freshwater shrimp in China and adjacent areas. It is advisable to use anaesthesia in this species for certain handling and shipping operations; however, there have been no investigations into the recommended dosages. Here, the influence of five menthol concentrations (varying from 100 to 500 mg/L) on three different size classes of P. sinensis were examined at 8, 12, 16, 20, 24 and 28°C. Induction and recovery times for each shrimp were recorded, and effects of temperature, size and menthol dose on induction and recovery times were observed. Results showed that menthol dose, water temperature and shrimp size significantly influence anaesthesia in P. sinensis. Induction time decreased linearly with increasing water temperature and concentration of menthol, and increased with body weight. However, recovery times lengthened with concentration and temperature, and became shorter with body weight. Average body weight of the shrimps generally decreased after anaesthesia. Mortality of shrimps was correlated with temperature, dose and size. These results suggest that menthol is an effective rapid anaesthetic for P. sinensis, but there may be some disadvantages, including slow recovery and possible mortality for small shrimps and at higher temperatures and dosages.
Despite their common use as model organisms in scientific experiments, pain and suffering in insects remains controversial and poorly understood. Here we explore potential pain experience in honeybees (Apis mellifera) by testing the self-administration of an analgesic drug. Foragers were subjected to two different types of injuries: (i) a clip that applied continuous pressure to one leg and (ii) amputation of one tarsus. The bees were given a choice between two feeders, one offering pure sucrose solution, the other sucrose solution plus morphine. We found that sustained pinching had no effect on the amount of morphine consumed, and hence is unlikely to be experienced as painful. The amputated bees did not shift their relative preference towards the analgesic either, but consumed more morphine and more solution in total compared to intact controls. While our data do not provide evidence for the self-administration of morphine in response to pain, they suggest that injured bees increase their overall food intake, presumably to meet the increased energy requirements for an immune response caused by wounding. We conclude that further experiments are required to gain insights into potential pain-like states in honeybees and other insects.
There are several reasons to believe that there is a predominance of suffering over wellbeing in nature. The difference grows exponentially when the suffering of invertebrates is taken into consideration. Given the relevance of the experience of pain when it comes to attributing moral considerability to an individual, the seriousness and implications of the above statements are significant due to the need to reconcile the interests of an enormous number of individuals who experience pain to some degree. Depending on the species and the ecosystem, there are variations that must be kept in mind with the aim of reducing the existing amount of suffering.
The welfare of invertebrates is overlooked and their needs are not understood. It is assumed that they do not experience pain and suffering. Studies on decapod crustaceans challenge this assumption. Research has focused on distinguishing between nociception (the ability to detect a harmful stimulus and to react to it reflexively) and pain (an aversive feeling or emotional experience). Findings indicate that decapod crustaceans can experience pain, which supports a case for protecting their welfare. I have investigated the current husbandry conditions of a globally consumed decapod crustacean, the lobster, as housed in tanks inside food outlets in the UK. Housing conditions of 325 lobsters were scored on four factors: restraints, stocking density, lighting and shelter. The data indicate that the basic requirements for lobsters are not being met, thereby compromising their welfare. I recommend research on the welfare of lobsters and other decapod crustaceans, not only when housed in tanks, but also during capture, handling and transport. Such information can be used to inform legislative change.
Organisms increasingly encounter higher frequencies of extreme weather events as a consequence of global climate change. Currently, few strategies are available to mitigate climate change effects on animals arising from acute extreme high temperature events. We tested the capacity of physiological engineering to influence the intra- and multi-generational upper thermal tolerance capacity of a model organism Artemia, subjected to extreme high temperatures. Enhancement of specific physiological regulators during development could affect thermal tolerances or life-history attributes affecting subsequent fitness. Using experimental Artemia populations we exposed F0 individuals to one of four treatments; heat hardening (28°C to 36°C, 1°C per 10 minutes), heat hardening plus serotonin (0.056 µg ml-1), heat hardening plus methionine (0.79 mg ml-1), and a control treatment. Regulator concentrations were based on previous literature. Serotonin may promote thermotolerance, acting upon metabolism and life-history. Methionine acts as a methylation agent across generations. For all groups, measurements were collected for three performance traits of individual thermal tolerance (upper sublethal thermal limit, lethal limit, and dysregulation range) over two generations. Results showed no treatment increased upper thermal limit during acute thermal stress, although serotonin-treated and methionine-treated individuals outperformed controls across multiple thermal performance traits. Additionally, some effects were evident across generations. Together these results suggest phenotypic engineering provides complex outcomes; and if implemented with heat hardening can further influence performance in multiple thermal tolerance traits, within and across generations. Potentially, such techniques could be up-scaled to provide resilience and stability in populations susceptible to extreme temperature events.
Crustaceans are aquacultured both for food and as ornamental organisms. Pain and distress are not entirely understood in crustaceans, but the industry is moving towards requiring protection for the welfare of these animals during handling. In the present study, we evaluated the efficacy of clove oil as an anaesthetic for redclaw crayfish (Cherax quadricarinatus) as a model for freshwater crustaceans. We also studied how factors such as body weight and sex of redclaw could affect this efficacy. The whole experiment was replicated in two consecutive years. Redclaw juveniles were sorted into three size classes: small (<5 g), medium (5–12 g) and large (12–37 g). At least 10 males and 10 females from each size class were placed individually in water containing clove oil concentrations of 375 and 500 μl/L. Both concentrations induced rapid induction and recovery times, with 500 μl/L being the more effective concentration of the two. Induction and recovery times increased with the increase in crayfish size. No significant differences were found in induction and recovery times between male and female crayfish. Results suggest that clove oil is an effective anaesthetic for redclaw.
Seafood draws on controversial themes in the interdisciplinary field of food studies, with case studies from different eras and geographic regions. Using familiar commodities, this accessible book will help students understand cutting-edge issues in sustainability and ask readers to think about the future of an industry that has lain waste to its own resources. Examining the practical aspects of fisheries and seafood leads the reader through discussions of the core elements of anthropological method and theory, and the book concludes with discussions of sustainable seafood and current efforts to save what is left of marine ecosystems. Students will be encouraged to think about their own seafood consumption through project assignments that challenge them to trace the commodity chains of the seafood on their own plates.
Seafood is an ideal book for courses on food and culture, economic anthropology, and the environment.
Decapod crustaceans are faceless animals with five pairs of legs, an external skeleton and multiple nerve centres (ganglia) rather than a single brain (as in vertebrates). They include common seafood species such as crayfish, crabs, lobsters, prawns and shrimp. These characteristics make them difficult to empathise with and consequently legal protection of decapods ranges from strong (Norway and New Zealand), through circumstantial (Australia and Italy) to non-existent (in many other countries). Whether they are capable of experiencing pain depends on definitions and the requirement for absolute proof of an inherently subjective psychological experience. Yet like other animals, decapods fulfil neuroanatomical, pharmacological and behavioural criteria that are consistent with a pain response. Whether they experience stress, harm and distress is less controversial because these conditions are more measurable than the pain response. To balance animal welfare concerns with scientific merit whilst providing confidence for the growing public awareness of crustacean welfare, use of decapod crustaceans in research should require ethical review.
All animals face hazards that cause tissue damage, and most have nociceptive reflex responses that protect them from such damage. However, some taxa have also evolved the capacity for pain experience, presumably to enhance long-term protection through behaviour modification based on memory of the unpleasant nature of pain. In this review, I consider various criteria that might help to distinguish nociception from pain. Because nociceptors are so taxonomically widespread, simply demonstrating their presence is not sufficient. Further, investigation of the central nervous system provides limited clues about the potential to experience pain. Opioids and other analgesics might indicate a central modulation of responses, but often, peripheral effects could explain the analgesia. Thus, reduction of responses by analgesics and opioids does not allow clear discrimination between nociception and pain. Physiological changes in response to noxious stimuli or the threat of a noxious stimulus might prove useful, but, to date, application to invertebrates is limited. Behaviour of the organism provides the greatest insights. Rapid avoidance learning and prolonged memory indicate central processing rather than mere reflexes and are consistent with the experience of pain. Complex, prolonged grooming or rubbing may demonstrate an awareness of the specific site of stimulus application. Trade-offs with other motivational systems indicate central processing, and an ability to use complex information suggests sufficient cognitive ability for the animal to have a fitness benefit from a pain experience. Recent evidence of fitness enhancing, anxiety-like states is also consistent with the idea of pain. Thus, available data go beyond the idea of just nociception, but the impossibility of total proof of pain means they are not definitive. Nevertheless, more humane care for invertebrates is suggested.
Decapod crustaceans (crabs, hermit crabs, lobsters, crayfish, shrimps, prawns) are sentient beings, not only responding to noxious stimuli but also being capable of feeling pain, discomfort, and distress. General anaesthesia aims at producing analgesia, immobilization, and unconsciousness, while sedation reduces consciousness, stress, and anxiety, though without analgesia. Anaesthesia is recommended to ensure animal welfare and suppress nociception, pain, and suffering in painful and distressing practice that impairs decapods’ welfare. These include long term restrain, surgical procedures, pain control, examination, diagnostic, sampling, treatment, transportation, and euthanasia. The necessary anaesthetic depth, from sedation to surgical anaesthesia, depends on the procedure type. Anaesthetic bath and injection are commonly used, besides inhalation, local anaesthesia, and intracardiac injection. Agents used for the anaesthetic bath include eugenol, isoeugenol, lidocaine, halothane, and essential oils of lemon balm, lemongrass, lemon verbena, and sandalwood. While alphaxalone, eugenol, ketamine-xylazine, lidocaine, morphine, procaine, tiletamine-zolazepam, and xylazine can be used as injectable agents administered on the arthrodial membrane or intramuscular injection. Halothane can be used on inhalation anaesthesia. Local anaesthetics include lidocaine and benzocaine. Notwithstanding, many others are detrimental or ineffective to decapods, thus discouraged. They include but not limited to hypothermia, carbon dioxide, chlorpromazine, chloroform, ethanol, ether, magnesium salts, tricaine methanesulfonate (MS-222), mint and lavender essential oils, passionflower extract, and valerian. Decapods’ welfare, protection, and veterinary attention should not be neglected, but they must receive ethical treatment, including the best of our knowledge and available tools to ensure they are free of pain and discomfort whenever we deal with them.
Analgesia and anesthesia of vertebrate and invertebrate aquatic animals are matters of increasing concern. Fortunately, data on the effective use of substances to minimize nociceptive response and stress in these species are growing, and they have been compiled herein. First, the aspects related to nociception, including the mechanisms of nociception transduction involving ion channels and G-protein-linked receptors, as well as facts about the major analgesics, are addressed. Then, on the subject of anesthesia, synthetic and natural alternatives which have been applied to these organisms are presented, along with specifications such as concentrations of the substance, characteristics of the test animals, and physiological outcomes triggered by exposure. Thus, this chapter presents the state of the art of this research area, which ultimately aims to ensure animal welfare.
The use of full spectrum illumination, including ultraviolet (UV), during captive husbandry of arachnids is common practice. The effect of this on captive arachnids has not been previously investigated. Comparison of key behavioral changes and hemolymph cortisol immunoreactivity was undertaken with and without full spectrum lighting. King baboon spiders, Pelinobius muticus and Indian giant scorpions, Heterometrus swammerdami were selected for the study. Both organisms spent all their time hidden when exposed to full spectrum light compared to low-level ambient light except for one instance. There was no significant difference in burrowing and webbing in P. muticus when exposed to full spectrum lighting. There was a decrease in the number of behaviors or postures expressed in full spectrum lighting compared to ambient light for both species. Cortisol immunoactivity of both species were significantly elevated after exposure to full spectrum lighting. This study provides the first evidence of detectable cortisol immunoactivity in arachnid hemolymph. These levels changed in response to full spectrum illumination and were linked to behavioral changes. This suggests that a common husbandry practice may be detrimental to arachnids.
Animal models of pain consist of modeling a pain-like state and measuring the consequent behavior. The first animal models of neuropathic pain (NP) were developed in rodents with a total lesion of the sciatic nerve. Later, other models targeting central or peripheral branches of nerves were developed to identify novel mechanisms that contribute to persistent pain conditions in NP. Objective assessment of pain in these different animal models represents a significant challenge for pre-clinical research. Multiple behavioral approaches are used to investigate and to validate pain phenotypes including withdrawal reflex to evoked stimuli, vocalizations, spontaneous pain, but also emotional and affective behaviors. Furthermore, animal models were very useful in investigating the mechanisms of NP. This review will focus on a detailed description of rodent models of NP and provide an overview of the assessment of the sensory and emotional components of pain. A detailed inventory will be made to examine spinal mechanisms involved in NP-induced hyperexcitability and underlying the current pharmacological approaches used in clinics with the possibility to present new avenues for future treatment. The success of pre-clinical studies in this area of research depends on the choice of the relevant model and the appropriate test based on the objectives of the study.
Soft‐shell crabs are gaining attention internationally as a more lucrative option of selling commercially important portunid species due to their ease of consumption, high nutritional values, and unique and excellent taste. This product, however, is only attainable in captivity as crabs are harvested right after moulting when their exoskeletons are still soft. Among the most crucial factor in soft‐shell crab production is the moult induction method. Shorter moult intervals imply more soft‐shell crabs could be produced, increasing productivity and profit for farmers. This review describes the moulting event, soft‐shell crab production process and production systems, and highlights the currently available and potential moult induction methods, including eyestalk ablation, limb autotomy, the use of ecdysteroid, phytoecdysteroid, biogenic amines and methyl farnesoate, the inhibition of moult‐inhibiting hormone (MIH) and the regulation of physical parameters. This review further compares these moult induction methods and their benefits towards soft‐shell crab production.
The development of aquaculture is closely related to human life. Crustaceans play essential roles in aquaculture. However, the cultivation of crustaceans has been plagued by various diseases, causing substantial economic losses. At present, the occurrence of shrimp diseases is directly related to environmental stress and physiological dysfunction, and especially environmental stress has become an important factor inducing diseases. Therefore, how to regulate the immune defence of crustaceans under environmental stress has become the primary problem in the prevention and control of shrimp diseases. The neuroendocrine‐immune system plays a vital role in maintaining homeostasis and enhancing environmental adaptability. Besides, in the evolutionary sense, with the theory that the nervous system and the immune system have a common origin put forward, the research on the neuroendocrine‐immune system of invertebrates has gradually become a hot spot. This review describes the evolution and communication mechanism of the neuroendocrine system and immune system in vertebrates and invertebrates, summarizes the characteristics of the neuroendocrine system and immune system in crustaceans, and focuses on how environmental stress affects the regulation of the neuroendocrine system on the immune system in crustaceans, as well as the influence of these regulations on host immune defence. This review also introduced the immune regulation of crustacean intestines under environmental stress and the effect of pathogen stress on crustacean immunity, hoping to lay a theoretical foundation for the follow‐up study of crustacean stress resistance and provide theoretical guidance for the healthy aquaculture of crustaceans.
Sentience is the capacity to have feelings, such as feelings of pain, pleasure, hunger, thirst, warmth, joy, comfort and excitement. It is not simply the capacity to feel pain, but feelings of pain, distress or harm, broadly understood, have a special significance for animal welfare law.
Drawing on over 300 scientific studies, we have evaluated the evidence of sentience in two groups of invertebrate animals: the cephalopod molluscs or, for short, cephalopods (including octopods, squid and cuttlefish) and the decapod crustaceans or, for short, decapods (including crabs, lobsters and crayfish). We have also evaluated the potential welfare implications of current commercial practices involving these animals.
Anthropocentrism and the perceived great dissimilarity of these animals compared to humans also help to explain the lack of concern, aversion, and even fear with which many people regard invertebrates. Concerns for animal welfare in vertebrate livestock production are similar to those for invertebrate production, especially when practiced on a large scale. Resources for information on invertebrate animal husbandry, biology, and medicine are listed in the "Recommended Reading" section. Invertebrate cognitive function is often thought to be limited, resulting in behavioral repertoires consisting primarily of reflexes or preprogrammed patterns. Invertebrates display other intriguing actions in response to stimuli that are believed to cause pain in vertebrate species. Physiological evidence for pain in invertebrates lies primarily with aspects of their neurochemical systems. Euthanasia of any animal should be performed humanely, manifested by providing for minimal pain and distress. A common practice among scientists for invertebrate specimen collection is submersion in a preservative substance.
This chapter deals with the conventional separation of crustaceans and insects. A number of crustaceans are maintained as pets and display animals in marine aquaria, especially shrimp. There are six classes within the subphylum Crustacea: Cephalocarida, Branchiopoda, Ostracoda, Remipedia, Maxillopoda, and Malacostraca. The types of diseases affecting crustaceans are in many cases similar to those affecting aquatic vertebrates and terrestrial mammals. Gas bubble disease is a noninfectious condition in aquatic organisms caused by supersaturated levels of total dissolved gas in water. Shell disease is a common term for areas of erosion and melanization in the exoskeleton in crustaceans. White spot disease is caused by white spot syndrome virus, the only member of the genus Whispovirus . Necrotizing hepatopancreatitis is a newly emerging disease caused by infection with the pathogenic agent Hepatobacter penaei . Hematodiniosis is a fatal disease of crustaceans caused by parasitic dinoflagellates of the genus Hematodinium .
An 8 weeks trial was performed to test the effects of light spectra [full-spectrum, violet (405 nm), blue (470 nm), cyan (500 nm), green (525 nm), yellow (570 nm), and red (625 nm)] on growth performance, molting, antioxidant capacity, stress response and expression of molting, and apoptosis-related genes in Scylla paramamosain . Results showed that spectrum had a significant effect on S. paramamosain physiology. Compared to blue light, crabs exposed to violet light had a significantly lower survival rate (79.5 ± 3.6% vs. 94.9 ± 3.6%), weight gain (49.2 ± 5.4 vs. 67.6 ± 6.7), molt frequency (4.2 ± 0.2 vs. 4.5 ± 0.1), and extended intermolt intervals between instar 1 and 2 stages (C1–C2) (6.3 ± 0.3 vs. 5.0 ± 0.1 days). Expression of the molt-inhibiting hormone ( mih ) gene was upregulated in crabs reared under violet light. According to the regression analysis, maximum SGR would be at 449.97 nm. Crabs exposed to blue light also had lower melatonin levels than under full-spectrum and lower cortisol levels than violet and yellow groups. Regarding oxidative stress, crabs in full-spectrum had lower H 2 O 2 and MDA contents, however, no significant difference was found in total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and catalase (CAT) in hepatopancreas from crabs under different spectra. Gene expression of hsp40 , hsp70 , hsp90 were down-regulated in crabs exposed to the full-spectrum light group. Regarding apoptosis-related genes, bcl-2 gene expression in crabs under cyan and the cox IV and caspase 3 in green were upregulated, suggesting cyan light may inhibit, while green light may promote apoptosis. Taken together, these results suggest that blue or cyan light would promote growth performance, while full-spectrum light could reduce stress response in S. paramamosain .
Nociception is the ability to encode and perceive harmful stimuli and allows for a rapid reflexive withdrawal. In some species, nociception might be accompanied by a pain experience, which is a negative feeling that allows for longer-term changes in behaviour. Different types of stimuli may affect nociceptors, but in crustaceans there is conflicting evidence about the ability to respond to chemical stimuli. This study attempts to resolve this situation by testing behavioural responses of the common shore crab, Carcinus maenas, to two chemical irritants frequently used in vertebrate pain studies (acetic acid and capsaicin). In our first experiment acetic acid, water, capsaicin or mineral oil were applied by brush to the mouth, and in a second experiment treatments were applied to the eyes. Application of acetic acid had a marked effect on behaviour that included vigorous movement of mouth parts, scratching at the mouth with the claws and attempts to escape from the enclosure. Acetic acid also caused holding down of the acid-treated eye in the socket. By contrast, capsaicin had no effect and was no different to the control treatment of mineral oil and water. These results demonstrate responsiveness to acetic acid and thus nociceptive capacity for at least some chemicals. Further, the responses that persist after application were consistent with the idea of pain, however, proof of pain is not possible in any animal.
Pain is an aversive sensation and feeling associated with actual or potential tissue
damage. A pain system involving receptors, neural pathways and analytical centres in
the brain exists in many kinds of animals. The fact that there is rather similar
evidence of physiological responses, direct behavioural responses and ability to learn
from such experiences so that they are minimised or avoided in future, suggests the
existence of feelings of pain in many species. Indeed the feelings are likely to be an
important part of the biological mechanism for coping with actual or potential
damage. The advantages of pain are that action can be taken when damage occurs,
consequent learning allows the minimising of future damage and, where the pain is
chronic, behaviour and physiology can be changed to ameliorate adverse effects.
Species differ in their responses to painful stimuli because different responses are
adaptive in different species but it is likely that the feeling of pain is much less
variable than the responses. The first steps in the evolution of pain must have
involved cell sensitivity and localised responses but substantial changes in efficacy
could occur once efficient communication within the individual and sophisticated
brain analysis could occur. Changes in the pain system, once there was a moderately
complex brain may well have been slight. Pain is an old system which has probably
changed rather little during vertebrate evolution and pain may be a greater problem in
animals with less cognitive ability. The distinction between pain and nociception
does not seem to be useful.
Pain is an aversive sensation and feeling associated with actual or potential tissue damage. A pain system involving receptors, neural pathways and analytical centres in the brain exists in many kinds of animals. Feelings of pain in many species are indicated by physiological responses, direct behavioural responses and ability to learn from such experiences so that they are minimised or avoided in future. Species differ in their responses to painful stimuli because different responses are adaptive in different species but the feeling of pain is probably much less variable. In early evolution, pain must have involved cell sensitivity and localised responses but efficacy would have improved with efficient communication within the individual and sophisticated brain analysis. Pain systems have probably changed rather little during vertebrate evolution. Pain may be a greater problem for animals with less cognitive ability. The distinction between pain and nociception does not seem to be useful.
The morphologies of the cerebral ganglia (brains) of three infraorders of the decapod crustaceans (Astacura-crayfish; Brachyura-crabs; Palinura-spiny lob- sters) are described. A common nomenclature is proposed for homologous nerve roots, brain regions, tracts, com- missures, neuropils, and cell body clusters.
A topical anesthetic and a coagulating agent were employed in this study to determine if observable signs of eyestalk ablation stress could be alleviated in adult female Litopenaeus vannamei broodstock. The experimental design included four separate treatments, with each tested group consisting of 15 female shrimp weighing approximately 40 g. Results show that survival of the shrimp was 100% for all treatments, but reaction to the eyestalk ablation event varied between treatments. Initiation of normal swimming or recovery and the onset of feeding following ablation and treatment also varied among the four groups. The results suggest that the use of a topical anesthetic prior to eyestalk ablation reduces the visible reactions to stress experienced by L. vannamei broodstock, allowing for a more humane eyestalk ablation method.
This review examines the neurobehavioral nature of fishes and addresses the question of whether fishes are capable of experiencing pain and suffering. The detrimental effects of anthropomorphic thinking and the importance of an evolutionary perspective for understanding the neurobehavioral differences between fishes and humans are discussed. The differences in central nervous system structure that underlie basic neurobehavioral differences between fishes and humans are described. The literature on the neural basis of consciousness and of pain is reviewed, showing that: (1) behavioral responses to noxious stimuli are separate from the psychological experience of pain, (2) awareness of pain in humans depends on functions of specific regions of cerebral cortex, and (3) fishes lack these essential brain regions or any functional equivalent, making it untenable that they can experience pain. Because the experience of fear, similar to pain, depends on cerebral cortical structures that are absent from fish brains, it is concluded that awareness of fear is impossible for fishes. Although it is implausible that fishes can experience pain or emotions, they display robust, nonconscious, neuroendocrine, and physiological stress responses to noxious stimuli. Thus, avoidance of potentially injurious stress responses is an important issue in considerations about the welfare of fishes.
Studies of the brain inform us about the cognitive abilities of animals and hence affect the extent to which animals of that species are respected. However, they can also tell us how an individual is likely to be perceiving, attending to, evaluating, coping with, enjoying, or disturbed by its environment, and so can give direct information about welfare. In studies of welfare, we are especially interested in how an individual feels. Since this depends upon high-level brain processing, we have to investigate brain function. Brain correlates of preferred social, sexual and parental situations include elevated oxytocin in the para-ventricular nucleus of the hypothalamus. Abnormal behaviour may have brain correlates, for example, high frequencies of stereotypy are associated with down-regulated μ and κ receptors and dopamine depletion in the frontal cortex. Such results help in evaluating the effects of treatment on welfare. Some brain changes, such as increased glucocorticoid receptors in the frontal lobes or increased activity in the amygdala, may be a sensitive indicator of perceived emergency. Active immunological defences lead to cytokine production in the brain, vagal nerve activity and sickness effects. Some aspects of brain function can be temporarily suppressed, for example, by opioids when there is severe pain, or permanently impaired, for example, in severely impoverished environments or during depression. Coping attempts or environmental impact can lead to injury to the brain, damage to hippocampal neurons, remodelling of dendrites in the hippocampus, or to other brain disorganisation. Brain measures can explain the nature and magnitude of many effects on welfare.
Opioid peptides have been revealed in representatives of practically all large taxonomic groups of invertebrates, and the opiate receptors are found even in unicellulars. The opioid system seems to belong to the evolutionary ancient signal systems. The comparative data indicate that the most conservative and ancient function of opioids is control of the adequate level of protective reactions. In the infusorian Stentor the opiate ligands suppress a contractile response to mechanical stimulation, i.e., the protective behavior. In all studies multicellular invertebrates, agonists also suppress protective behavior, whereas antagonists produce opposite effects. This initially signal meaning of opioids might have become a basis for divergent development of their functions in evolution. Already in higher invertebrates, molluscs and arthropods, many functions of opioids, for example, stress-induced analgesia, regulation of feeding and mating behavior, of social aggression, are similar to those in vertebrates. It is suggested that the main events in formation of functions of the endogenous opioid system have occurred in the lower invertebrates that have remained so far the least studied.
When red deer (Cervus elaphus) were hunted by humans with hounds the average distance travelled was at least 19 km. This study of 64 hunted red deer provides the first empirical evidence on their state at the time of death. Blood and muscle samples obtained from hunted deer after death were compared with samples from 50 non-hunted red deer that had been cleanly shot with rifles. The effects on deer of long hunts were (i) depletion of carbohydrate resources for powering muscles, (ii) disruption of muscle tissue, and (iii) elevated secretion of beta-endorphin. High concentrations of cortisol, typically associated with extreme physiological and psychological stress, were found. Damage to red blood cells occurred early in the hunts; possible mechanisms are discussed. Taken together, the evidence suggests that red deer are not well-adapted by their evolutionary or individual history to cope with the level of activity imposed on them when hunted with hounds.
In Pagurus bernhardus, the relative sizes of the crabs and shell quality of the larger crab influenced the probability of occurrence of a shell fight. These two factors along with the quality of the smaller crab's shell influenced the probability of an escalated fight occurring. During a shell fight, the attacker was able to assimilate information concerning the defender's shell and to compare it with the shell in possession. On the basis of this comparison the attacker decided whether or not to evict the defender and effect a shell change. The defending crab did not have access to information about the attacker's shell and therefore could only estimate the quality of its own shell. This asymmetry of information experienced by the crabs ensured that the attacker decided the outcome of a shell fight.-from Authors
More than 200 years ago, Lazzaro Spallanzani (Accademia d’Italia, 1934) wondered how birds — sand martins in his case — found their way back home after they had been displaced inadvertently to unknown territory, but the first to marvel at the amazing homing abilities of insects was Jean Henri Fabre (1879, 1882). He released some megachilid bees and sphecid wasps up to 4 km away from home and was surprised to find that many of them returned to their nesting sites the very same day. Even though he performed a number of experiments including the attachment of tiny magnets to the homing bees, he finally was left with the conclusion that his experimental animals possessed some enigmatic sense of directionality. Nevertheless he started what can be called the first period of research on homing in insects. In this period, which culminated in the discovery of the insect’s celestial compass (Santschi, 1911, 1923; see Wehner, 1990a), most investigators focused on the sensory basis of insect navigation.
Avian pain is likely analogous to pain experienced by most mammals. Approach to pain management for the avian patient involves considering the duration, type, and extent of injury along with physical, environmental, and behavioral management. Invasive, painful procedures should always be accompanied by appropriate analgesia and anesthesia. Although pain management in birds is in its infancy, research and clinical studies demonstrate benefit for use of opioids, steroidal and nonsteroidal anti-inflammatory drugs, as well as other analgesics such as α2-agonists, ketamine, and local anesthetics. Ongoing assessment of pain and analgesic efficacy is extremely important, because the dosage and choice of analgesic may vary widely between species.
In contrast to nociception, the perception of pain, or pain experience, remains a subjective notion applicable to humans, but untestable with animals. Yet, when defined operationally as a physiological response induced in an animal by stimuli painful to humans, and resulting in a protective stimulus avoidance response, pain is amenable to testing with non-human subjects. This paper considers a series of examples showing responses to stimuli that are both painful (nociceptive) and responsible for eliciting natural self-preserving behavior in Invertebrates. Consideration is also given to the evolution and possible mechanism underlying the "pain-system" in Invertebrates.
An alternative collection procedure for pregnant mare urine (PMU) has been developed in Australia, which allows mares to be loose housed either in indoor stables or outdoors in paddocks, rather than in tether stalls as is common practice in Canada and North Dakota. The present study examined the welfare risks to mares of collecting urine using this alternative procedure. The study involved 24 pregnant mares at 3–5 months of gestation. The mares were allocated to two treatments: 12 mares were fitted with the pregnant mare urine collection device and 12 mares acted as controls. All mares were housed in two large paddocks during the day, in two groups of 12. During the night, all mares were housed in six small enclosures in groups of four, while the PMU treatment mares wore the collection device.Mares wearing the PMU collection device showed little or no behavioural change relative to the control mares. While brief bouts of forward lifting of the hind leg in the region of the PMU collection device were observed in some mares on day 1, this disappeared by day 2. Observations on the time budgets of behaviour in weeks 3 and 6–7 indicated similar patterns of behaviour in the two treatments. The only difference in behaviour was in lying behaviour. PMU collection mares spent less (P
The behaviour of the hermit crabClibanarius vittatuswas studied as it investigated shells prior to and during shell exchange interactions. Crabs behaved in a manner predicted by the negotiations model of resource exchange, that is, shells were primarily exchanged between crabs when both crabs benefited in shell fit from the exchange. During initial investigation of shells, crabs in poorly fitting shells selected shells that (1) were similar to the preferred shell size of the investigating crab and (2) that did not fit their current occupant well. In addition, the greater the shell deficit (deviation from that crab's preferred shell size) of the other crab, the more likely it was investigated by a crab in a poorly fitting shell. Considering three factors (initiator's preferred shell size, current shell deficit of the non-initiator and magnitude of gain possible for the non-initiator) explained 86% (multipler=0.93) of the variance in shells rapped by initiating crabs. In those interactions that proceeded to rapping behaviour, the magnitude of gain in shell fit that the non-initiating crab would experience if a shell exchange occurred helped explain which shells were selected for rapping. The relative size of the two crabs was only important in the assessment and decisions process once rapping began, and the number of raps was inversely proportional to the relative size difference of the crabs.
Factors which influence decisions by hermit crabs concerning whether to approach, investigate and enter another shell have been investigated by systematically varying the size of the shell in possession and the size of the shell being offered. The probability that a crab will approach or enter the shell depends on both variables. Investigation after contact, however, depends only on the size of the shell in possession. Durations of each stage of the sequence are negatively correlated with the numbers of crabs in each experimental group performing the next stage. For the final sequence of aperture investigatory activities, the fewer crabs entering the offered shell, the greater the number of investigatory acts performed by those crabs. In addition to variation in number of acts and duration of investigation, specific use of appendages varies according to the experimental situation. Thus naked crabs use the minor cheliped to investigate shells in preference to the major cheliped, which is normally used by housed crabs, with the major cheliped being reserved for defence by naked crabs. These data are discussed in terms of information collection and decisions made on the basis of that information.
Feeding ability and motivation were assessed in the edible crab, Cancer pagurus, to investigate how the fishery practice of de-clawing may affect live crabs returned to the sea. Crabs were either induced to autotomise one claw, or were only handled, before they were offered food. Initially, autotomised and handled crabs were offered mussels, Mytilis edulis, a large part of their natural diet. After 3 days, both autotomised and handled crabs were then offered fish, a more readily handled food source. Autotomy induced crabs consumed significantly fewer mussels and less mussel mass, but ate significantly more mass of fish. This indicates that the effect of autotomy was a reduction of ability to feed on mussels rather than a general reduction of feeding motivation. The discontinuation of claw removal needs to be considered, both for the sustainability of the fishery and animal welfare concerns.
Previous work showed that goldfish learn to avoid a region of an aquarium where they receive a discrete shock to the flank. This avoidance is reduced if another fish is present next to the shock zone, suggesting fish trade-off avoidance against a tendency to associate [Dunlop, R., Millsopp, S., Laming, P., 2006. Avoidance learning in goldfish (Carassius auratus) and trout (Oncorhynchus mykiss) and implications for pain perception. App. Anim. Behav. Sci. 97 (2–4), 255–271]. Only shock intensity was adjusted in those experiments, here we report results where a requirement for food was also altered.Fish were trained to feed at a region of the aquarium where subsequently they would receive a discrete shock to the flank. One experimental group had different shock intensities applied, whereas in the other group shock intensity was consistent but food deprivation was varied.We show the number of feeding attempts and time spent in the feeding/shock zone decreased with increased shock intensity and with increased food deprivation the number and the duration of feeding attempts increased as did escape responses as this zone was entered. These data suggest that goldfish balance their need for food against avoidance of an acute noxious stimulus.
This paper discusses the evidence for pain perception in fish and presents new data on morphine analgesia in fish. Recent anatomical and electrophysiological studies have demonstrated that fish are capable of nociception, the simple detection of a noxious, potentially painful stimulus and the reflex response to this. To prove pain perception, it must be demonstrated that an animal’s behaviour is adversely affected by a potentially painful event and this must not be a reflex response. The present study examined the acute effects of administering a noxious chemical to the lips of rainbow trout (Oncorhynchus mykiss) to assess what changes occurred in behaviour and physiology. There was no difference in swimming activity or use of cover when comparing the noxiously stimulated individuals with the controls. The noxiously treated individuals performed anomalous behaviours where they rocked on either pectoral fin from side to side and they also rubbed their lips into the gravel and against the sides of the tank. Opercular beat rate (gill or ventilation rate) increased almost double fold after the noxious treatment whereas the controls only showed a 30% increase. Administering morphine significantly reduced the pain-related behaviours and opercular beat rate and thus morphine appears to act as an analgesic in the rainbow trout. It is concluded that these pain-related behaviours are not simple reflexes and therefore there is the potential for pain perception in fish.
An understanding of receptors and mechanisms involved in pain and suffering is essential in selecting proper methods of treatment. Detection of pain, knowing types of pain, and understanding reasons why presurgical administration of analgesic drugs (pre-emptive analgesia) is essential to relief of pain and distress. Animals feel pain to the same extent as humans and they have a wide variation in tolerance to pain stimuli as well. Animals may express pain or discomfort in two ways. Excessive activity or relative lethargy are both overt reflections of a painful state. Expressions of pain may be exhibited by moaning, groaning, crying, whimpering, looking at the painful area, licking or biting or simply a decrease in activity. Pain may be categorized as minor, moderate, or severe. Pain may be superficial, somatic (muscle and skin), or visceral or combinations. Moderate and severe pain always require treatment and visceral pain is usually more intense than somatic pain. Opiate receptors are the normal sites of action of several endogenous substances. There are three major types of opioid receptors designated as mu, kappa and sigma. Opioids and opioid antagonists have different affinities for different receptors. Agonist analgesics such as morphine, meperidine, fentanyl, and oxymorphone exert their effects by attaching to the mu receptors. A relatively pure antagonist, naloxone, will displace another compound on these receptors but exert little or no effect. The mixed drugs, agonist–antagonists or partial agonists, may be used as analgesics if no opioid compound has been used, or as antagonists to reverse the effects of an opioid on the mu receptor while at the same time not competing with the effects on the k receptor that is, preserving the analgesia provided by that receptor. Some of the mixed drugs are better agonists wile others are better antagonists. Animals recovering from surgery are often surprised and confused because they hurt and therefore sedation along with analgesia preanesthesia is often desirable and necessary for proper treatment of postsurgical pain. Therefore, giving an analgesic before surgery will be advantageous. The second choice is to give analgesics after surgery, but before recovery from anesthesia.
Pain is mediated by functionally distinctive components. It may involve acute high threshold afferent stimuli (thermal, mechanical or chemically damaged tissue), protracted afferent input (long-lasting hyperalgesia) or low-threshold input (allodynia as related to pain from light touch). Behavioral patterns will be associated with the effects of noxious stimulus on excitatory transmitters. Humane studies using mechanical, thermal (cold pressor test), audio-evoked potentials, or other noxious stimuli during anesthesia and analgesia provide clues to perception of pain in animals and help us determine guidelines for the clinical relief of animal pain. There is a better understanding of cutaneous somatosensory responses than for deep sensation (e.g., subcutaneous tissue, muscle, bone, viscera). The prevention or treatment of pain can best be accomplished when there is a diagnosis of the neuroanatomical distribution of the pain based on evidence of sensory dysfunction involving a peripheral nerve, plexus, nerve root or central pathway using different modalities for quantitative sensory testing. Anatomical studies have demonstrated that unmyelinated primary afferent fibers contain a variety of neuroactive substances which may be released by high-intensity peripheral stimulation. Fast depolarization of the dorsal horn nociresponsive neurons is mediated by tissue damage. These neuroreceptors may be activated by glutamate, substance P, and neurokinin A. The major ascending pathway relaying nociceptive information relating to pain is the spinothalamic tract. Most of the neurons in this tract are nociceptive or thermoreceptive. The thalamus is the final relay nucleus for all the sensory systems, except olfactory tissue. Injury or disease processes in deeper tissue or visceral areas with extensive innervation may result in pain thresholds not adequately controlled by current available analgesics or at their recommended dosage levels. These issues are complex and diagnosis is even more difficult due to species and breed differences in outward expression to painful insult. Medications can now be targeted for specific receptors.
It is a popular notion that, compared to vertebrates, invertebrates have a reduced capacity to experience suffering. This is usually based on arguments that invertebrates show only simple forms of learning, have little memory capacity, do not show behavioural responses to stimuli that would cause 'higher' vertebrates to exhibit responses indicative of pain, and have differences in their physiology that would preclude the capacity for suffering. But, how convincing is this 'evidence' of a reduced capacity to suffer? Suffering is a negative mental state – a private experience – and, as such, it cannot be measured directly. When assessing the capacity of an animal to experience suffering, we often compare the similarity of its responses with those of 'higher' animals, conceptualized in the principle of argument-by-analogy. By closely examining the responses of invertebrates, it can be seen that they often behave in a strikingly analogous manner to vertebrates. In this paper, I discuss published studies that show that invertebrates such as cockroaches, flies and slugs have short- and long-term memory; have age effects on memory; have complex spatial, associative and social learning; perform appropriately in preference tests and consumer demand studies; exhibit behavioural and physiological responses indicative of pain; and, apparently, experience learned helplessness. The similarity of these responses to those of vertebrates may indicate a level of consciousness or suffering that is not normally attributed to invertebrates. This indicates that we should either be more cautious when using argument-by-analogy, or remain open-minded to the possibility that invertebrates are capable of suffering in a similar way to vertebrates.
The ease of autotomy in Hemigrapsus oregonensis was tested by crushing the propodite of each walking leg. Individual curves of percent autotomy in groups of 18–21 animals were drawn for six different sequences of stimulation. Lumped data show peaks in ease of autotomy for the third anatomical leg of each side and for the second leg stimulated regardless of anatomical position. Later autotomies are more severely depressed when the stimulation sequence is from posterior to anterior. Segmental and lateral interaction and the characteristics of individual responses suggest that autotomy of legs in the crab, while depending upon specific structural features of the legs, is less a unisegmental reflex, than an accident occurring during escape.
In an experiment with 10 experimentally naive male hooded rats, it was found that when 1 member of a pair of Ss was insulated from electric footshock, a frequency of aggression was obtained which was far lower than that which has typically been reported in the shock-elicited aggression literature. Also the shocked Ss developed a relatively high frequency of stereotyped responses which served as partially successful avoidance responses. Data support earlier data indicating that avoidance or escape responses to shock will take priority over attack responses to shock. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Crustacean discards experience stress during commercial fishing operations, due to increased exercise while in the trawl and aerial exposure during sorting of the catch. Physiological stress and recovery were assessed following trawling of two ecologically important decapod species, regularly discarded in the Clyde Nephrops fishery. Haemolymph samples taken from trawled swimming crabs, Liocarcinus depurator, and squat lobsters, Munida rugosa, had significantly higher concentrations of ammonia (0.308 and 0.519 mmol l-1), -glucose (0.14 and 0.097 mmol l-1) and -lactate (6.2 and 0.87 mmol l-1) compared with controls, indicating an impairment of ammonia excretion and a switch to anaerobic metabolism. Concurrently, the haemolymph pH of trawled squat lobsters was low (7.47) compared with controls (7.75); however, the reverse trend was found in L. depurator. Initially elevated lactate (7.98 mmol l-1) and glucose (0.73 mmol l-1) concentrations of trawled and emersed (1h) L. depurator were restored, 4h after re-immersion along with pH (7.54). Crabs that had been emersed for 1 h had significantly higher concentrations of glucose (0.2 mmol l-1) and lactate (5.14 mmol l-1), and had more acidic blood (7.64) than L. depurator subject to 1h of exercise, indicating that anoxia was the main cause of physiological stress. Crabs and squat lobsters lost 7% and 9% of their initial body wet weight following 1h of emersion, although blood osmolarities did not change significantly. While all animals survived aerial exposure in our experiments, sorting of the catch on commercial boats takes up to 300min, which could lead to mortality or sub-lethal chronic biochemical changes that could compromise fitness.
We investigated the possibility that invertebrates recognize conspecific individuals by studying dominance relationships in the long-clawed hermit crab, Pagurus longicarpus. We conducted three sets of laboratory experiments to define the time limits for acquiring and maintaining memory of an individual opponent. The results reveal two characteristics that make individual recognition in this species different from standard associative learning tasks. Firstly, crabs do not require training over many repeated trials; rather, they show evidence of recognition after a single 30-min exposure to a stimulus animal. Secondly, memory lasts for up to 4 d of isolation without reinforcement. A third interesting feature of individual recognition in this species is that familiar opponents are recognized even before the formation of a stable hierarchical rank. That is, recognition seems to be relatively independent of repeated wins (rewards) or losses (punishments) in a dominance hierarchy. The experimental protocol allowed us to show that this species is able to classify conspecifics into two ‘heterogeneous subgroups’, i.e. familiar vs. unfamiliar individuals, but not to discriminate one individual of a group from every other conspecific from ‘a unique set of cues defining that individual’. In other words, we demonstrated a ‘binary’– and not a ‘true’– individual recognition. However, 1 d of interactions with different crabs did not erase the memory of a former rival, suggesting that P. longicarpus uses a system of social partner discrimination more refined than previously shown.
To Charles Darwin, it was obvious that animals are sentient, so why should the idea not be now universally accepted? I review the difficulties and issues with animal sentience with a view to answering some of the critics. Sentience is 'the hard problem' and it is important we acknowledge the difficulties and do not claim too much for the evidence we have. Two sorts of evidence are examined: evidence from animal cognition and evidence from animal emotion, including the ways we now have of 'asking' animals what they want, behaviour, brain imaging and parallels with our own emotions. Despite the problems, the study of animal sentience is one of the most important areas of biology. Although conclusive evidence that animals are sentient may elude us, evidence of what they want and how they see the world is increasingly open to us and it is important that it is used. There is a danger that well-meaning people define animal welfare in terms of what they think animals want or what pleases them. But if we take animal sentience seriously, we must ensure that the animal voice is heard. # 2006 Published by Elsevier B.V.
The Clyde Sea Nephrops fishery produces large amounts of invertebrate discards. Of these, as much as 89% are decapod crustaceans, including the
swimming crab Liocarcinus depurator (Linnaeus, 1758), the squat lobster Munida rugosa (Fabricius, 1775) and the hermit crab Pagurus bernhardus (Linnaeus, 1758). The short-term mortality of these species was assessed following trawling and periods of aerial exposure
on deck (16–90 min), and ranged from 2–25%, with Pagurus bernhardus showing the lowest mortality. Two experiments were performed to determine the longer-term survival of trawled decapods compared
to those with experimentally ablated appendages. Deliberately damaged decapods had a significantly lower longer-term survival
(ca. 30%) than controls (72–83%). Survival of trawled Liocarcinus depurator that had been induced to autotomize two appendages was slightly lower (74%) compared with intact creel-caught animals (92%).
Mortality rates stabilised about 10 d after trawling. Our results suggest that post-trawling mortality of discarded decapod
crustaceans has been underestimated in the past, owing to inadequate monitoring periods.
Animals are routinely subjected to painful procedures, such as tail docking for puppies, castration for piglets, dehorning for dairy calves, and surgery for laboratory rats. Disease and injury, such as tumours in mice and sole ulcers on the feet of dairy cows, may also cause pain. In this paper we describe some of the ways in which the pain that animals experience can be recognized and quantified. We also describe ways in which pain can be avoided or reduced, by reconsidering how procedures are performed and whether they are actually required. Ultimately, reducing the pain that animals experience will require scientific innovation paired with changed cultural values, and willingness to address regulatory, technological and economic constraints. # 2006 Published by Elsevier B.V.
In this paper I explore the value of invertebrates to human society. I initially examine various ecological, utilitarian, scientific, and cultural benefits provided by invertebrate organisms. I then explore the extent of appreciation and understanding of these values among the American public. This assessment was based on a study of residents of the state of Connecticut, including randomly selected members of the general public, farmers, conservation organization members, and scientists. The general public and farmers were found to view most invertebrates with aversion, anxiety, fear, avoidance, and ignorance. Far more positive and knowledgeable attitudes toward invertebrates and their conservation were observed among scientists and, to a lesser extent, among conservation organization members. I finally examine the motivational basis for hostile attitudes toward invertebrates, particularly arthropods among the general public. Important factors include the possibility of an innate learning disposition, the association of many invertebrates with disease and agricultural damage, differences in ecological scale between humans and invertebrates, the multiplicity of invertebrates, the apparent lack of a sense of identity and consciousness among invertebrates, the presumption of mindlessness among invertebrates, and the radical autonomy of invertebrates from human control.
Can suffering in non-human animals be studied scientifically? Apart from verbal reports of subjective feelings, which are uniquely human, I argue that it is possible to study the negative emotions we refer to as suffering by the same methods we use in ourselves. In particular, by asking animals what they find positively and negatively reinforcing (what they want and do not want), we can define positive and negative emotional states. Such emotional states may or may not be accompanied by subjective feelings but fortunately it is not necessary to solve the problem of consciousness to construct a scientific study of suffering and welfare. Improvements in animal welfare can be based on the answers to two questions: Q1: Will it improve animal health? and Q2: Will it give the animals something they want? This apparently simple formulation has the advantage of capturing what most people mean by ‘improving welfare’ and so halting a potentially dangerous split between scientific and non-scientific definitions of welfare. It can also be used to validate other controversial approaches to welfare such as naturalness, stereotypies, physiological and biochemical measures. Health and what animals want are thus not just two of many measures of welfare. They provide the definition of welfare against which others can be validated. They also tell us what research we have to do and how we can judge whether welfare of animals has been genuinely improved. What is important, however, is for this research to be done in situ so that it is directly applicable to the real world of farming, the sea or an animal’s wild habitat. It is here that ethology can make major contributions.
We examined physiological stress responses in the edible crab, Cancer pagurus, subjected to the commercial fishery practice of manual de-clawing. We measured haemolymph glucose and lactate, plus muscular
glycogen and glycogen mobilisation, in three experiments where the crabs had one claw removed. In the first, crabs showed
physiological stress responses when ‘de-clawed’ as compared to ‘handled only’ over the short term of 1–10min. In the second,
de-clawing and the presence of a conspecific both increased the physiological stress responses over the longer term of 24h.
In the third, de-clawing was shown to be more stressful than ‘induced autotomy’ of claws. Further, the former practice caused
larger wounds to the body and significantly higher mortality than the latter. Since the fishery practice is to remove both
claws, the stress response observed and mortality data reported are conservative.
The mantis shrimpSquilla mantis responds to an electrical shock with a quick and violent flexure of its body (Fig. 1 and 2). The reaction time of this defensive response was measured for each experimental shrimp and the minimal current that elicited a reaction time equal to or lesser than 0.22 s was considered as its intensity threshold (Fig. 3). Different doses of morphine-HCl were injected and results showed that this drug produces a dose-related analgesia by increasing the intensity threshold. A concentration of morphine equal to 30.0 μg/mm of animal length (about 91.0 μg/g) causes a 50% inhibition in the sensitivity to the electrical stimulus, but the effect is fully blocked by naloxone (Table 2).
The present study represents the first behavioral analysis of opiate effects in invertebrates. However, the effective dose reported in this experiment is far greater than that used with vertebrates. Some speculative arguments are mentioned in order to account for a such large difference.
1.
Kinesthetic reorientation to the burrow as already assumed to be present in Uca tangeri (R. Altevogt u. H. O. v. Hagen, 1964) was shown in Uca rapax by field experiments in Trinidad (West Indies).
2.
The kinesthetic orienting mechanism is found to operate with striking precision within a certain area around the burrow and is able to control distance as well as direction (bi-coordinate or vector orientation).
3.
When missing the burrow Uca after a motionless interval starts zigzagging transversely to the previous direction. These locomotions are interpreted as searching movements.
4.
According to a few supplementary experiments, U. leptodactyla can reorient kinesthetically as well, and the related ghost crab, Ocypode quadrata, is at least capable of kinesthetic distance control.
5.
Some observations (especially on patterns of feeding pellets) indicate a possible ability of kinesthetic detour integration in Uca.
6.
In the discussion an attempt is made to classify some examples of kinesthetic orientation known from literature. Three types are given: kinesthetically controlled stereotyped locomotion, kinesthetic reorientation, kinesthetic distance indication.
This article reviews three studies of agonistic interactions in pairs of swimming crabs (Liocarcinus depurator and Necora puber) in which behavioural and physiological approaches were combined. In both species most fights were won by the larger crab. Smaller crabs were able to win fights when the size differential was small, in which case encounters tended to be long and fierce. In N. puber both the larger and the smaller crab were more likely to win fights that they initiated, suggesting that motivational differences (perhaps related to resource value) as well as relative size determine what crabs do during a fight. When fighting during the breeding season in water in which receptive females had been housed, small crabs were as likely as large ones to win fights, by persisting much longer than they did in the absence of such stimuli. In L. depurator an absolute size effect was found, with larger crabs fighting for longer regardless of relative size. This suggested that costs fall more heavily on smaller crabs, and prompted a study of the respiratory costs of fighting. Using scaphognathite beat as an index of oxygen consumption, aerobic respiration was found to be greatly elevated during fights and to remain high for some time after the fight had ended. Long and/or intense fights involved a greater increase in respiration rate. Winners and losers had similar average respiration rates during fights but, in losers, long fights were associated with significantly elevated respiration rates during the recovery period. Analysis of tissue metabolites gave little evidence of anaerobic respiration during fights, although some local mobilisation of glucose in the walking legs was observed. No significant effects of participation in a fight were found on initiation or outcome of a second fight staged immediately afterwards. Sequential associations between agonistic acts indicate a short-term escalatory process that was more marked in winners than losers, which tended to de-escalate especially during high intensity phases. The insights gained by combining behavioural and physiological techniques are discussed.
The supratidal shore crab Leptograpsus variegatus makes use of aquatic as well as terrestrial habitats. The respiratory responses of this species to 12 h immersion in 100% seawater and re-emersion were investigated. The major perturbation was in haemolymph CO2, the PCO2 declining to 2.2 torr after 2 h in water compared to >4 torr in air-breathing crabs. Similarly, CCO2 decreased from 12.8 typical of air breathing to 5.0 mmol · l−1, more typical of water breathing species. This internal hypocapnia promoted an alkalosis which was immediately compensated by a metabolic acidosis that was not a product of anaerobiosis since l-lactate in the haemolymph remained low (0.14 mmol · l−1). When re-emersed, haemolymph CO2 did not increase to pre-immersion values but, instead, evinced a smaller elevation after 3 h access to air. Control Leptograpsus that could choose between water and air showed intermediate but more variable haemolymph CO2 values, suggesting that the animals ‘shuttle’ between air and water, behaviourally influencing internal CO2 levels.
This review on homing in decapods, which has been shown by Herrnkind (1983) and Wehner (1992), indicates how scarce our knowledge is, not only on the physiological mechanisms involved in such behaviour but also on the reality and extent of the behaviour itself.The case studies cited (first part) show that among decapods (only “reptants” are considered here), some species seem to wander at random, some can keep within a more or less well defined home range with no particular “home” while yet others are known to relocate periodically a definite restricted goal. Although burrows and shelters are the primary homing goals, cases of relocation of food resources and mates have also been reported. Some decapods occupy a single shelter, while others tend to visit, on a more or less regular basis, a system of shelters. The second part of this review deals with the mechanisms involved in decapod homing. Apart from idiothetic mechanisms, visual cues certainly play the most important role among terrestrial or semi-terrestrial species. Chemical cues may play a role in benthonic species, although direct evidence for this is still lacking. In certain cases a cognitive map relying on a system of orienting cues can be inferred.
Judgements about pain and suffering in animals are required by the law of many countries and by many professional guidelines. Nevertheless, such assessments raise many problems, even in humans. Furthermore, an appeal to continuities between humans and other animals is clouded when, as is still the case, both the evolution and the function of a subjective sense of pain are obscure. Despite these difficulties, the criteria that lead to the judgement that a human is in pain can be generalized with substantial measure of agreement to other animals. This generalization is done on the basis of uncovering comparable mechanisms and comparable behaviour; then the whole cluster of features found in the animal is used to make the judgement. The less similar the animal to a human and the less complex it is, the more difficult is the assessment. The fuzziness of the boundary between those animals that are judged to feel pain and those that are not does not invalidate the process of assessment. However, the extent to which an animal is given the benefit of the doubt clearly depends on the empathy a person feels for it as well as the type of ethical concerns that motivate the person.
Energetic costs of fighting, such as high lactate or low glucose, have been shown in a range of species to correlate with the decisions made by each opponent, particularly the decision by one opponent, the ‘loser’, to end the fight by ‘giving up’. Studies based on complete fights of differing duration, however, do not provide information on the changes in the physiological correlates of fighting that may take place during the course of the encounter, or how these changes may influence the capability and decisions of the contestants. We interrupted fights between hermit crabs, Pagurus bernhardus, at specific points, and related energy status to the preceding activities. Costs rose quickly with a rapid accumulation of lactic acid in attackers and declining muscular glycogen in defenders. Changes in physiological status appeared much earlier than the changes in behaviour that they may have caused. Furthermore, some physiological changes might have been an effect, rather than the cause, of fight decisions.
Animal fights are typically preceded by displays and there is debate whether these are always honest. We investigated the prefight period in hermit crabs, Pagurus bernhardus, during which up to four types of display plus other activities that might provide information are performed. We determined how each display influences or predicts various fight decisions, and related these displays to the motivational state of the attacker, as determined by a startle response, and of the motivational state of the defender, as determined by the duration for which it resisted eviction from its shell. Two displays appeared to have consistent but different effects. Cheliped presentation, where the claws were held in a stationary position, often by both crabs but for longer by the larger, seemed to be honest, and allowed for mutual size assessment. This display enhanced the motivation and the success of the larger crab. In contrast, cheliped extension, involving the rapid thrust of the open chelae towards the opponent, did not seem to allow for mutual size assessment and may contain an element of bluff. It was performed more by the smaller crab and enhanced its success. The complexity of displays in this species appears to allow for both honesty and manipulation.
Nociception is the ability to perceive a noxious stimulus and react in a reflexive manner and occurs across a wide range of taxa. However, the ability to experience the associated aversive sensation and feeling, known as pain, is not widely accepted to occur in nonvertebrates. We examined the responses of a decapod crustacean, the prawn, Palaemon elegans, to different noxious stimuli applied to one antenna to assess reflex responses (nociception) and longer-term, specifically directed behavioural responses that might indicate pain. We also examined the effects of benzocaine, a local anaesthetic, on these responses. Noxious stimuli elicited an immediate reflex tail flick response, followed by two prolonged activities, grooming of the antenna and rubbing of the antenna against the side of the tank, with both activities directed specifically at the treated antenna. These responses were inhibited by benzocaine; however, benzocaine did not alter general swimming activity and thus the decline in grooming and rubbing is not due to general anaesthesia. Mechanical stimulation by pinching also resulted in prolonged rubbing, but this was not inhibited by benzocaine. These results indicate an awareness of the location of the noxious stimuli, and the prolonged complex responses indicate a central involvement in their organization. The inhibition by a local anaesthetic is similar to observations on vertebrates and is consistent with the idea that these crustaceans can experience pain.