Water uptake in terrestrial hermit crabs: a morphofunctional analysis (original) (raw)
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Respiration and Adaptation to the Terrestrial Habitat In the Land Hermit Crab Coenobita Clypeatus
Journal of experimental …, 1979
The frequencies of heart (f H ) and scaphognathite (ventilatory = / Bo ) pumping, and responses to hypoxia, hypercapnia and wetting (simulated rain), as well as oxygen consumption (M o% ), pre-and postbranchial haemolymph oxygen tension (P o ,)> oxygen content (C Oi ), carbon dioxide content (Ceo,) a n d pH were measured in adult land crabs Coenobita clypeatus. There was a large increase in / 8C in response to both hypoxia and wetting but a smaller increase in response to even severe hypercapnia. Some evidence suggests that ventilation via the scaphognathites may have been supplemented by a second (branchiostegal) pump when ventilatory requirement was high. f H was less responsive to either hypoxia or hypercapnia, but decreased with severe exposure to either. Haemolymph oxygen tensions were low (Po.o, = 14, P vOt = 8) but haemocyanin oxygen affinity was high in vivo (P K = 10 torr at 23 °C) and postbranchial haemocyanin was 60-80% saturated. Oxygen content was also high allowing adequate oxygen release to the tissues despite the low oxygen tensions. AP M /A* = 0-37 torr/A °C, log AP M /ApH = -0-84 torr/pH unit, both determined in vitro were lower than literature values for marine and littoral species. As in other terrestrial species, C COt and PQO, (calculated) were high, as were both bicarbonate and non-bicarbonate buffering capacities. Water loss was less (0-08% body weight, h" 1 ) in Coenobita than in other terrestrial crustaceans, this resulting from the protection of the adopted shell. Results obtained from Coenobita are compared with those from other terrestrial and littoral crabs to illustrate the influence of the adopted shell on the degree of modification needed to enter terrestrial habitats.
2020
Extensively distributed along tropics and subtropics, terrestrial hermit crabs play critical roles in coastal ecology and they often show preferences towards few gastropod shells in natural ecosystems. The nature of selection of empty gastropod shells as protective ‘home’ from natural environment for shelter varies with species. In this study the vacant shell search and selection by the terrestrial hermit crab Coenobita rugosus (Coenobitidae; Crustacea) was found to be governed by various parameters including the presence of vacant shells in vicinity, types of vacant shells, and morphometric characters of shells. Laboratory simulation for 72 hours of exposure of hermit crab to different types of vacant host shell combinations followed by statistical evaluation revealed specific relationship in shell selection by hermit crab with morphometric characteristics of vacanthost shells.They also exhibit a greater plasticity in shell selection.
Journal of Zoology, 2005
Terrestrial hermit crabs use mollusc shells to protect their soft bodies from predation and desiccation, but their use is costly. The energetic short-term cost of using shells has been demonstrated, yet this could theoretically be overcome by increasing feeding rate or food quality. In the long term, shells have the potential to constrain growth, which may in turn have a negative effect on fitness. Thus crabs should choose the lightest (least expensive to carry) shell amongst those of a size that permit growth. Since in nature lighter shells are also thinner-walled, these may provide insufficient protection from predation or desiccation, facing the crabs with a trade-off between protection and growth. This potential trade-off was investigated in the terrestrial hermit crab Coenobita compressus. Crabs were individually maintained in captivity for a variable period of between 1 and 7 months, during which light or heavy replicates of the preferred shell were available. In a second experiment, crabs were given a choice between a thick (and heavy) or a thin (and light) shell. In addition, the resistance and water retention capacity of thin and thick shells was compared. As predicted, crab growth was negatively correlated with the weight of the shell used, but crabs rejected the thin (light) shells. Thin shells were more likely to break when crabs used the normal 'rolling' behaviour in response to perceived threats. In addition, thin shells lost water at a faster rate than thick ones. Since two putative functions of shell use in terrestrial hermit crabs are protection against predation and against desiccation, it is inferred that the preference for shells of intermediate weight in C. compressus results from a balance between the need to grow and the cost of carrying a brittle shell that is not sufficiently water tight.
Chromatic Patterns of the Hermit Crab Calcinus tubularis Related to the Occupied Shell
Hydrobiologia, 2006
Crustacea are known to develop different chromatic patterns due to many factors. Regarding decapods, chromatism was mainly studied in crabs, while very little is known about chromatic patterns in hermit crabs. Calcinus tubularis is a typical infralittoral rocky bottom hermit crab, studied for different aspects of its biology except chromatic variations. This paper aims at describing the different colour morphologies of C. tubularis, discussing hypothesis of why they develop, and testing if in nature the crab prefers a shell with a chromatic pattern similar to that of its body. One hundred and forty crabs were observed and filmed in the laboratory. They were subdivided into two groups, according to their chromatic pattern: 1) light and 2) dark crabs; the shells they occupied were also subdivided into the two groups of 1) light and 2) dark shells on the basis of the epibionts encrusting them. Observations of 129 crabs suggest that the colour depends neither on depth nor on size, intermoult period, diet, reproductive period but it might be connected to genetic factors and might help crab to camouflage. Camouflage is suggested by the fact that 79.3% of the total examined specimens occupy shells with a chromatic pattern resembling that of the crabs themselves. This phenomenon is significantly more recurrent in females than in males and could help the crabs to be cryptic, first with the occupied shell and secondly with the habitat (rocks encrusted by photophylous algae).
Marine and Freshwater Behaviour and Physiology, 2009
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Energetics of Hermit Crabs during Locomotion: The Cost of Carrying a Shell
Journal of Experimental Biology
Oxygen consumption (VO Z ) was measured as hermit crabs (Coenobita compressus) walked at controlled velocities on a motor-driven treadmill inside a small respirometer. The crabs displayed an aerobic response to exercise with a rapid increase in VQ 2 reaching a steady state in about 5-6 min followed by a rapid recovery. The highest VQ 2 was four times the resting rate. V^ was directly dependent on the velocity of travel (V): V Q2 = 0*29+1*98V. Metabolic rate was increased significantly in crabs with bilateral leg ablation.
Hydrobiologia, 2014
Hermit crabs recognize different shell attributes and choose shell size, type, or species to maximize their individual fitness. Aquatic hermit crab species commonly prefer relatively heavy shells species in contrast to semi-terrestrial crabs which prefer lighter shells. Lighter shells favor rapid growth and increase individual fitness because larger individual achieve higher success in intra-and inter-individual competition. In this study, we experimentally measured the daily growth of hermit crabs Calcinus californiensis that were forced to occupy four different shell species with different internal volume to mass ratios (IV/M ratio), and whose sequence in preference is known from previous studies (Cantharus [ Stramonita [ Columbella [ Nerita). The shell with the highest IV/M ratio (Nerita) favored body growth rate, while the relatively heaviest (lowest IV/M ratios) and most preferred shells (Stramonita and Cantharus) hindered body growth. Our results suggest that in this aquatic hermit crab, the benefits of carrying heavy shells that give better predatory protection exceeded the benefits of rapid growth that can be obtained using lighter, thinner, and less protective shells. Keywords Calcinus californiensis Á Gastropod shell Á Growth Á Hermit crabs Á Shell mass Á Shell preference Hydrobiologia
Shell recruitment in the Mediterranean hermit crab< i> Clibanarius erythropus
2009
Gastropod shells are vital for the majority of hermit crab species, being essential for their survival, growth, protection, and reproduction. Given their importance, shells are acquired and transferred between crabs through several modalities. We conducted observations and experiments at the Asinara Island (Sardinia, Italy) to investigate the efficacy of the different behavioral tactics adopted by the hermit crab Clibanarius erythropus to acquire shells, such as: (1) locomotion and activity at different tidal phases; (2) attendance at shell-supplying sites (simulated predation sites with five different odors: live and dead gastropods, live and dead crabs, predator); and (3) interactions with conspecifics in aggregations on simulated gastropod predation sites. In each tidal phase, locomotion was slow (0.7 cm min − 1) and, as a consequence, the probability of encountering empty shells and conspecifics was low. Simulated gastropod predation sites quickly attracted a larger number of hermit crabs than the other sites tested. Aggregations seemed to function as shell exchange markets, as previously suggested for other species: the first attendant took the experimental shell and a chain of shell exchanges among conspecifics followed. Our results show that, in C. erythropus, aggregation is the most efficient tactic for the acquisition of new shells, whereas in other species, such as Pagurus longicarpus, it is associated with exploitation ability due to the intense locomotion. The interspecific plasticity in hermit crabs' behavior is confirmed.