Chemosensation in the Daily Life of Crabs (original) (raw)
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Marine and Freshwater Behaviour and Physiology, 1997
The red‐jointed fiddler crab Uca minax is one of the most abundant macroinvertebrates inhabiting the temperate western Atlantic salt marshes, along the eastern and southern coasts of the United States. Dactyl chemoreception is the primary sensory modality involved in food detection. Ninety‐six chemoreceptor cells from 69 male and female second and third legs were tested with 20 compounds known to be stimulatory in other decapods. Each compound was tested as 1 s pulses at 10‐3M. Overall, chemoreceptor cells on the dactyls responded strongest to glutamate and ammonium chloride followed by citric acid. Glutamate‐ and ammonium chloride‐best cells formed the most prominent cell populations and were relatively narrowly tuned. Individual cells exhibited a range of tuning breadths based on responses to single compounds. Amines were moderately stimulatory. Surprisingly, hexose sugars which cause strong behavioural responses in U. minax elicited only weak physiological responses. Glutamate sensitivity separates U. minax from other species of fiddler crabs. The results indicate that the chemical response spectrum of U. minax includes compounds that occur naturally in salt marshes as algal and animal constituents, exudates, and decomposition products.
Journal of Experimental Marine …, 2009
This study tested the hypothesis that physiological condition is a key factor in determining the outcome of intraspecific agonistic interactions for food in male shore crabs Carcinus maenas of equal body size. Physiological condition was manipulated by maintaining crabs under different food regimes (using the cockle Cerastoderma edule) in combination with exposure to a sub-lethal concentration (200 µg L − 1 ) of pyrene, a polyaromatic hydrocarbon (PAH). After 14 days, crabs were used in staged agonistic interactions, whereby, an unexposed crab was paired with a pyrene-exposed crab from the same dietary regime, using a whole cockle (C. edule; 0.35 ± 0.05 g wet weight) as the limited resource. Agonistic behaviour was recorded over 15 min, then crabs were separated and their energetic status was assessed based on haemolymph glucose and lactate concentrations. Fully-fed (fed 2 g of food each day) crabs had significantly higher concentrations of circulating glucose and lactate compared to starved (no food) and diet-restricted crabs (fed 1 g of food on alternate days after an initial starvation period of 3 days). In fully-fed crabs, blood glucose concentrations were lower, on average, in individuals exposed to pyrene. Physiological condition had no significant effect on most behavioural measures used to describe the agonistic behaviour in crabs (e.g. number of fights, number of wrestles, fight duration, wrestle duration, contest duration and contest intensity); however, starved pyrene-exposed individuals had significantly higher resource possession (defined as % time in possession of the resource) and significantly decreased inter-bout intervals (defined as time spent away from an opponent after an agonistic encounter) compared with starved unexposed individuals. Results show that a reduced physiological condition ('lower' RHP) in starved contaminant-exposed crabs resulted in an unexpected increased competitive ability over starved unexposed individuals.
PeerJ, 2021
Swimming crabs have a characteristic fifth pair of legs that are flattened into paddles for swimming purposes. The dactyl of these legs bears a thick seta along its edge. The chemoreceptive and feeding properties of the seta are supported with scientific evidence; however, there is no available data on the sensitivity of the setae in portunid crabs. The underlying mechanisms of the chemo- and mechano-sensitivity of appendages and their involvement in feeding activities of the mud crab (Scylla paramamosain) were investigated using electrocardiography and behavioural assay, which focused on the responses of the mud crab to chemical and touch stimulus. Electrocardiography revealed the sensory properties of the appendages. The dactyls of swimming legs and the antennules were chemosensitive, but not mechanosensitive and vice versa for the antennae. However, the mouthparts, claws, and walking legs were chemo- and mechanosensitive. Only the chemosensitive appendages, including the swimming...
Chemoreception in Two Species of Terrestrial Hermit Crabs (Decapoda: Coenobitidae)
Journal of Crustacean Biology, 1997
The capability of terrestrial hermit crabs to detect volatile chemicals in the air does not only concern food-related substances, but may also be used to identify water-related cues. Coenobita rugosus and C. cavipes from Kenya (which in the field exhibit, respectively, high and low levels of terrestrial adaptation) were tested in an olfactometer, with air flows carrying food-and water-related odors. Coenobita rugosus could only barely perceive the odor of coconut, but reacted well to water-related odors. These hermit crabs could detect the difference between fresh water and sea water and orient themselves appropriately, probably according to their hemolymph concentration, while C. cavipes could not. In nature, such an ability might have an important function in terrestrial species for the detection of water sources irregularly distributed inland. Preliminary tests showed that the capability of reacting to water-related odors is also present in C. brevimanus, the most terrestrial of the species of Coenobita, but is probably missing in C. perlatus, among the less terrestrial species.
Chemosensory orientation of the rock crab Cancer irroratus
Journal of chemical ecology, 1999
AbstractThe importance of chemical cues in the foraging behavior of the rock crab, Cancer irroratus, was investigated. Crabs were presented with mussel prey located upstream, downstream, or cross-stream. Trials were conducted under both light and dark conditions. ...
Journal of Chemical Ecology, 1984
Abstraet-Chemosensitivity to secondary plant substances was examined electrophysiologically and behaviorally for the lobster Homarus americanus. Neurophysiological experiments show that some chemoreceptor cells in the antennules (representing the sense of smell) and walking legs (representing the sense of taste) were excited by secondary compounds from plants of marine and terrestrial origin. These compounds include amygdalin, atropine sulfate, bromoform, caffeine, p-coumaric acid, diiodomethane, ferulic acid, heliotropin, phloroglucinol, quinine sulfate, salicin, sinigrin, tannic acid, and tomatine. The possible behavioral function of three of these compounds was tested. Phloroglucinol and ferulic acid had no observable effect on any aspect of feeding behavior at any concentration tested. Tannic acid, which is related to polyphenols found in marine algae, had no observable effect at any concentration tested on orientation to and grasping of food (activities controlled primarily by antennular and leg chemoreceptors, respectively) but did have an inhibitory effect on food ingestion (an activity controlled primarily by mouthpart chemoreceptors). These electrophysiological and behavioral results suggest that potential chemoreceptive information derived from many secondary plant compounds may not be used in feeding behavior. The receptors sensitive to these compounds may represent a "common chemical sense" as suggested by Dethier (1980). However, at least one compound, tannic acid, that is smelled and tasted by lobsters can function as a feeding inhibitor at the level of the mouthparts.
Reduced pH sea water disrupts chemo-responsive behaviour in an intertidal crustacean
Chemoreception is a key activity by which many aquatic animals perceive their environment, and therefore abiotic disruptions to this process could have serious impacts on the survival and fitness of individuals, and on species interactions. Hermit crabs are subject to cyclical reductions in the pH of the water in the intertidal rock pools that they inhabit. Such reductions may be further exacerbated by ongoing ocean acidification and/ or leakage of carbon dioxide from geological storage sites and coastal upwelling events. Here we test the chemo-sensory responses of the hermit crab Pagurus bernhardus (Linnaeus) to a food odour under reduced pH conditions (pH NBS = 6.80). Acidifying the odour had no effect on its attractiveness indicating no permanent degradation of the cue; however, the pH of the sea water did affect the crabs' responses. Hermit crabs kept and tested in reduced pH sea water had lower antennular flicking rates (the 'sniffing' response in decapods); were less successful in locating the odour source, and showed an overall decline in locomotory activity compared to those in untreated sea water. Analysis of their haemolymph revealed a greater concentration of chloride ions ([Cl − ]) in the reduced pH treatment group, suggesting iono-regulatory disruption; however, there was no correlation between [Cl − ] and locomotory activity, suggesting a specific effect on chemoreception. This study shows that the chemo-responsiveness of a crustacean may be influenced by both naturally occurring pH fluctuations and future anthropogenically-induced changes in ocean pH.
Chemosensory Basis of Feeding Behavior in Pacific White Shrimp, Litopenaeus vannamei
The Biological Bulletin, 2020
The Pacific white shrimp, Litopenaeus vannamei, is important as the principal species in the worldwide aquaculture of shrimp. It has also become a model in the study of crustacean biology, especially because it is one of the first decapod crustaceans to have its genome sequenced. This study examined an aspect of the sensory biology of this shrimp that is important in its aquaculture, by describing its peripheral chemical sensors and how they are used in acquiring and consuming food pellets. We used scanning electron microscopy to describe the diversity of sensilla on the shrimp's major chemosensory organs: antennules, antennae, mouthparts, and legs. Using behavioral studies on animals with selective sensory ablations, we then explored the roles that these chemosensory organs play in the shrimp's search for, and acquisition and ingestion of, food pellets. We found that the antennules mediate odor-activated searching for pellets, with both the lateral and medial antennular flagella contributing to this behavior and thus demonstrating that both aesthetasc (olfactory) and distributed chemosensors on the antennules can mediate this behavior. Once the shrimp finds and grasps the food pellet, the antennular chemoreceptors no longer play a role, and then the chemoreceptors on the mouthparts and legs control ingestion of the pellets. This sequence of chemosensory control of feeding in L. vannamei, a dendrobranchiate crustacean with small antennules and an ability to live and feed in both benthic and pelagic environments, is generally similar to that of the betterstudied, large-antennuled, benthic reptantian crustaceans, including spiny lobsters (Achelata), clawed lobsters and crayfish (Astacidea), and crabs (Meirua).
Aversive responses by shore crabs to acetic acid but not to capsaicin
Behavioural processes, 2017
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 ...