Sympatric Hermit Crabs Research Articles

Coexistence of two sympatric hermit crab species from South Brazil: the effect of the shell adequacy index and circadian movement patterns

Coexistence of two sympatric hermit crab species from South Brazil: the effect of the shell adequacy index and circadian movement patterns

Study on Shell Utilization Pattern of Two Sympatric Hermit Crab Species on the Rocky Intertidal Region of Veraval, Gujarat, India

The present study illustrates the shell utilization and resource partitioning of two sympatric hermit crab species Clibanarius rhabdodactylus and Clibanarius ransoni with reference to gastropod shell species (shell shape), shell size and shell availability. Specimens were collected from January to March 2021 and hermit crab weight and shield length were measured. The gender of occupant hermit crab was identified and categorised into male, non-ovigerous female and ovigerous female. Gastropod shells were identified and different morphological parameters like shell length, shell aperture length and width, shell volume and dry weight were measured. The population of C. rhabdodactylus and C. ransoni was female biased with male: female ratio being 1:1.93 and 1:1.25 respectively. Clibanarius rhabdodactylus and C. ransoni were occupying 29 species and 28 species of gastropod shells respectively among which > 75% occupied shells were comprised of Cerithium caeruleum, Lunella coronata, Turbo bruneus, Tenguella granulate and Pollia undosa. Both the Clibanarius species were showing a high overlap in their intertidal distribution as well as gastropod shell use pattern. Cerithium caeruleum was found to occur in high abundance as compared to other gastropod species in the study area which may also influence the shell utilization of hermit crab species. Males and non-ovigerous females of the hermit crab species utilized almost all shell species, while ovigerous females used only a few shell species. Significant relationship was observed between different morphological parameters of the occupant crab species and occupied shells. Shell partitioning was evident between hermit crab sexes as well as reproductive stages on the basis of occupied shells of different species, shapes, and sizes. The present study revealed shell occupation pattern of C. rhabdodactylus and C. ransoni is highly influenced by the diversity, morphology and availability of gastropod shells in the study area.

Shell use by sympatric hermit crab species in a seasonally open coastal lagoon in Northeastern Brazil

AbstractThere are gaps in what is known about the patterns of gastropod shell use by hermit crabs in Brazilian lagoon areas, especially in Northeastern Brazil. However, this is important because the understanding of selection patterns provides information on life history and eco‐evolutionary conceptions of paguroids. The present study investigated the use of gastropod shells occupied by Pagurus criniticornis and Clibanarius sclopetarius in a coastal lagoon seasonally connected to an estuary and to the sea, correlating eco‐evolutionary aspects and hydrodynamic characters. The study was carried out between February 2013 and January 2014. Hermit crabs and their shells were identified and measured (hermit crabs’ cephalothorax shield length and width, major propodus length and height, weight, shell total length and width, shell aperture length and width). Partial least squares regression was used to analyse the morphometric data. Additionally, a multinomial proportions test was performed to infer patterns (inter‐/intra‐specific) of shells’ occupation. Hermit crab species occupied a total of 13 types of shells, predominantly those of Neritina virginea (67.83%). The shell weight was the most important determinant of shell occupancy in the morphometric model (variable importance in projection >1). The proportions of N. virginea shells used were similar in both species of hermit crabs, except between the sexes of P. criniticornis. Presumably, the high utilization rate of N. virginea shells is related to its abundance and dispersal, and to the shells’ suitability for hermit crabs, which is reflected by the morphometric model, as well as by the hydrodynamics of the lagoon‐estuarine environment. The relative occupation of different types of shells for each species of hermit crabs studied appears to be associated with regulation by inter‐/intra‐specific competition, which fosters the co‐occurrence of those populations. These results endorse coastal lagoons as a refuge and recruitment area for aquatic fauna. In addition, it highlights a challenge in the management and conservation of paguroid species whose population dynamics depend on the resources coming from the Gastropoda community.

Allometric relationships and sexual dimorphism in three ubiquitous hermit crab species (Anomura, Diogenidae) from a tropical mangrove estuary

Shield length-weight relationship (LWR) and relative growth were studied in three tropical hermit crab species, Diogenes moosai Rahayu & Forest, 1995, Diogenes lopochir Morgan, 1989, and Clibanarius infraspinatus (Hilgendorf, 1869). Overall, the length exponent (b) for LWR ranged between 2.67 to 3.28 with males of both Diogenes species showing positive allometry () and females showing negative allometry (), whereas that of both sexes of C. infraspinatus showed negative allometry. Males had larger b values than females in all species, indicating that males are heavier than females of equal shield length. In all species, relative growth of cheliped and chela exhibited positive allometry () with distinct sexual dimorphism whereby males bear longer chelipeds and chelae compared to females of equal shield lengths. Intra- and interspecific variations in growth of body and cheliped among the three sympatric hermit crab species allow for the resource partitioning of their vital shell resources.

Aggression and Food Resource Competition between Sympatric Hermit Crab Species

The vertical zonation patterns of intertidal organisms have been topics of interest to marine ecologists for many years, with interspecific food competition being implicated as a contributing factor to intertidal community organization. In this study, we used behavioral bioassays to examine the potential roles that interspecific aggression and food competition have on the structuring of intertidal hermit crab assemblages. We studied two ecologically similar, sympatric hermit crab species, Clibanarius digueti [1] and Paguristes perrieri [2], which occupy adjacent zones within the intertidal region of the Gulf of California. During the search phase of foraging, C. digueti showed higher frequencies of aggressive behaviors than P. perrieri. In competition assays, C. digueti gained increased access to food resources compared to P. perrieri. The results suggest that food competition may play an important role in structuring intertidal hermit crab assemblages, and that the zonation patterns of Gulf of California hermit crab species may be the result of geographical displacement by the dominant food competitor (C. digueti).

Subjective resource value and shell abandoning behavior in hermit crabs

Understanding the factors that motivate animals to hold or abandon a valuable resource is a central goal of behavioral ecology, the study of which will grow more important in the face of increasingly frequent extreme events. We compared the shell-abandoning behavior of the sympatric hermit crabs Clibanarius antillensis and Pagurus criniticornis in response to simulated burial and entrapment by rocks and other debris. While these hazards are relatively common in dynamic intertidal habitats, the frequency and severity of such disturbance are increasing due to human activity. While both species exhibited shell-abandoning behavior in response to experimental burial, it was far more prevalent for the soft-bottom dwelling species P. criniticornis (90%) when compared to the rocky bottom inhabitant C. antillensis (55%). Simulated entrapment experiments highlighted further differences in species response, with the decision to abandon domicile shells again far more common for P. criniticornis (80%) than it was for C. antillensis (10%). Given the tendency for P. criniticornis to abandon its shell, we subsequently focused on this species to test specific hypothesis about subjective resource value in hermit crabs. There was no difference in the tendency for this species to abandon optimal or sub-optimal (poorly-fitting) shells when faced with the immediate and potentially fatal risk of burial. This contrasted the response seen under conditions of entrapment, whereby individuals inhabiting sub-optimal shells abandoned them more rapidly and in greater numbers than those inhabiting optimal shells. Combining these two outcomes, we suggest that hermit crabs subjectively assess shell-value and respond according to the nature of the disturbance and its associated risks (i.e., high-value shells are abandoned in minutes under conditions of burial; but are held for hours under the less severe conditions of entrapment). In effect, the results show that extrinsic environmental cues can be just as important to decision making processes as those intrinsic cues that govern an animal's physiological condition. The contrasting behavior of the two hermit crabs to the movement of mud and other debris may lead to a higher survivorship of P. criniticornis than C. antillensis where activities such as dredging and harbor construction are intensifying along developing coastlines.

Reproduction strategies and population dynamics of two Diogenes hermit crabs (Superfamily: Paguroidea) in a tropical mangrove estuary

Two species of sympatric hermit crab, Diogenes moosai Rahayu & Forest, 1995 and D. lopochir Morgan, 1989, spatially defined in the Matang mangrove estuary, and facing high mortality due to tidal emersion, predation and competition are hypothesised to adopt different reproductive strategies for successful recruitment. The crabs were sampled by a small otter trawl at mid-estuary, river mouth, mudflat and shoal area along the estuary to adjacent coastal area. Diogenes moosai was widespread in the mudflat as well as in the subtidal shoal area where D. lopochir was dominant. Diogenes moosai showed year-round reproduction, whereas D. lopochir a discontinuous spawning pattern. Major reproduction in both species, however, occurred in January/February and July which resulted in two major recruitment pulses in a year. Diogenes moosai also suffered very high mortality resulting from cockle harvesting on the mudflat, twice that of D. lopochir. Our results show that the more widespread species at higher risk of exposure to extreme physical conditions (in the mudflat), predation and competition for shell resources, generally spreads its reproduction over the year, while the dominantly subtidal species at greater risk of predation only reproduces less regularly but at the most favourable period.

Shell use and partitioning of two sympatric species of hermit crabs on a tropical mudflat

Shell use and partitioning of two sympatric hermit crab species (Diogenes moosai and Diogenes lopochir), as determined by shell shape, size and availability, were examined from August 2009 to March 2011 in a tropical mudflat (Malaysia). Shells of 14 gastropod species were used but >85% comprised shells of Cerithidea cingulata, Nassarius cf. olivaceus, Nassarius jacksonianus, and Thais malayensis. Shell partitioning between hermit crab species, sexes, and developmental stages was evident from occupied shells of different species, shapes, and sizes. Extreme bias in shell use pattern by male and female of both species of hermit crabs suggests that shell shape, which depends on shell species, is the major determinant of shell use. The hermit crab must however fit well into the shell so that compatibility between crab size and shell size becomes crucial. Although shell availability possibly influenced shell use and hermit crab distribution, this is not critical in a tropical setting of high gastropod diversity and abundance.

Divergent reactions to olfactory foraging cues between two ecologically similar, sympatric hermit crab species

Relatively little is known about how sensory differences between species can influence community dynamics and interspecific competition. For animals that rely on chemical (olfactory) cues to forage, subtle differences in the olfactory capabilities between species could influence the foods that the species consume and thus permit coexistence between ecologically similar species. This study identified olfactory foraging cues used by two ecologically similar, sympatric hermit crab species, Clibanarius digueti Bouvier, 1898 and Paguristes perrieri Bouvier, 1895. Additionally, the behavioral chemosensitivities to olfactory cues were compared between the two species. Results show that the two species use different chemical cues to mediate their foraging behaviors, despite similarities in their olfactory chemosensitivity. This sensory differentiation provides a plausible mechanism by which the species relax interspecific food competition enough to permit coexistence.

Regional variation in shell utilization patterns of the hermit crab Pagurus filholi

Shell utilization patterns of the intertidal hermit crab Pagurus filholi were compared between two distant local populations from Oura Bay, Shimoda, central Japan, and Hakodate Bay, Hakodate, northern Japan, in conjunction with the shell resource availability and shell utilization patterns of sympatric hermit crabs. Gastropod species of shells dominantly utilized by P. filholi differed between Oura Bay and Hakodate Bay, and shell utilization patterns did not correspond to the availability of shells in both study localities. Between P. filholi and other sympatric hermit crabs, there were some clear differences in shell species utilized in both localities, and values of niche overlap indices in shell and habitat utilizations between P. filholi and other crabs were higher in Hakodate Bay than in Oura Bay. The rich supply of shell resources in Hakodate Bay compared to Oura Bay is considered to be a factor responsible for the difference in the degree of niche overlapping between the two localities.

Shell partitioning of two sympatric hermit crabs, Pagurus middendorffii and P. brachiomastus, in north-eastern Hokkaido, Japan

The distribution, reproductive biology and shell utilization pattern of two sympatric hermit crab species in Akkeshi, north-eastern Hokkaido, were examined. Although spatial distributions of Pagurus middendorffii and P. brachiomastus highly overlapped and their body sizes were similar, their shell utilization and breeding season markedly differed. Since interspecific differences in the shell utilization pattern agreed with the experimentally determined shell preference difference, we conclude that the interspecific difference in shell preference results in the shell utilization patterns observed in the field. The interspecific difference in the reproductive period, shell utilization pattern and shell preference are concluded to be factors that allow the coexistence of the two Pagurus species in Akkeshi. This study is an example of resource partitioning by coexisting hermit crabs.

Spatial distribution and shell utilization in three sympatric hermit crabs at non-consolidated sublittoral of estuarine-bay complex in São Vicente, São Paulo, Brazil

El objetivo de este estudio fue definir la distribucion de tres especies de cangrejo ermitano y la utilizacion de conchas en el sublitoral no consolidado del complejo bahia-estuario de Sao Vicente, Provincia de Sao Paulo, en Brasil. Las muestras fueron retiradas mensualmente durante dos anos consecutivos. Factores ambientales como temperatura, salinidad y profundidad, tambien fueron registrados todos los meses. Las tres especies de ermitanos Clibanarius vittatus, Loxopagurus loxochelis e Isocheles sawayai fueron capturadas con la utilizacion de la concha de seis especies de gasteropodos; 92,7% de los individuos utilizaron conchas de Stramonita haemastoma. Los resultados indicaron una fuerte asociacion entre la distribucion espacial de los ermitanos y la salinidad, que mostro ser el principal factor limite de su distribucion en ese estuario. I. sawayai fue la unica especie presente en todos los lugares muestreados en este estudio; C. vittatus fue capturado solamente en los lugares de menor salinidad y L. loxochelis estaba presente solo donde la salinidad se mantuvo con altos niveles.

Population structure and reproduction of three sympatric species of hermit crabs in the north-western Mediterranean

The populations of three sympatric hermit crabs, Pagurus excavatus, Anapagurus alboranensis and Anapagurus petiti were studied in a shallow (15–25 m) sandy area in the north-western Mediterranean. Seasonal abundance, seasonal size frequency, sex ratio and reproductive periods were examined. Pagurus excavatus was the largest and most abundant species in the zone. Pagarus excavatus and Anapagarus alboranensis are sexually dimorphic in relation to size, with males reaching larger sizes than females. However, the males and females of Anapagurus petiti reach similar large sizes. Anapagurus petiti has a sex ratio that is female biased, whereas A. alboranensis and P. excavatus are 1:1. Anapagurus petiti showed a higher reproductive activity during warmer seasons, while in A. alboranensis the proportion of ovigerous females was high throughout the year, with a minimum in autumn. The activity and clutch size of P. excavatus decreased during summer.

Shell-size selection by intertidal sympatric hermit crabs

This study evaluated selection for shell size by three species of tropical intertidal hermit crabs, Clibanarius antillensis, C. sclopetarius, and C. vittatus, from species of shells which are frequently used in nature. Crab size and weight were strongly and significantly related to all measured parameters of the selected shells. The strength of these relationships (r2 values) depended neither on the crab nor on the shell variables taken into account. The relationships between crab size and the dimensions of the selected shells showed higher r2 values than the corresponding relationships with the shells that the crabs had occupied when they were collected (0.482–0.903 in comparison to 0.091–0.652, respectively), indicating that the crabs were occupying sub-optimal shells in nature. Negative allometry was frequently found in the relationships between crab and shell variables, indicating that large crabs select and use proportionally lighter shells than do small crabs. This negative allometry was stronger for the shells used in nature (except for C. antillensis), i.e. larger crabs tended to select heavier shells in the laboratory than in nature. Different allometric relationships were also recorded among the dimensions of shells used in nature and those selected by the hermit crabs in free-access experiments: as shell length increased, the selected shells were heavier and had larger apertures than the shells used in nature. The relationships between crab size and the length and weight of the selected shells did not depend on the species of crab or species of shell, but only on crab size. Therefore, analyses using these variables can be performed without taking the species of crab or shell into account, i.e. data from different crab or shell species can be pooled. The influence of crab and/or shell species was recorded only in the models fitted for aperture length and width, variables which were more related to shell architecture than did shell length or weight. In contrast, if crab weight is used as an independent variable, different crab or shell species can be analyzed together independently of the particular shell parameter. This indicates that crab weight may be less susceptible than crab shield length to shell morphological constraints. Finally, the results indicate that the preferred size of a given shell type chosen by a given hermit crab will depend more on crab size or weight, than on the crab or shell species under consideration, i.e. crab shell-size relationships are not species specific.

Temporal and spatial settlement patterns of sympatric hermit crabs and the influence of shell resource availability

Larvae of marine organisms often need specific resources or environments at settlement, and their success at settlement might be strongly influenced by the abundance and distribution of such specific resources. The larvae of hermit crabs need small shells to settle, so it is thought that the distribution and abundance of small shells influence the settlement pattern of hermit crabs. To investigate the influence of small shell distribution on the settlement of pagurid hermit crab larvae, we conducted a field experiment at an intertidal rocky shore in Hakodate Bay, Japan. From the line-transect sampling in the field, we found that Pagurus middendorffii settled extensively in the offshore side of the intertidal zone while P. nigrofascia settled in the uppermost area of the intertidal zone. Small shells were most abundant in a narrow shallow trough, slightly offshore from the uppermost area of the intertidal zone. For both species, settler abundance was high where adults were abundant, but settler abundance did not appear to be related to shells abundance. An experiment to clarify settlement patterns showed that larval recruits tended to be similar to those in the line-transect sampling of settlers. Thus shells may not be a primary factor affecting settlement patterns at relatively large scale within the intertidal flat. However, when we analyzed the relationship of settlers and shells separately within each transect, the distribution of settlers was well explained by shell resource availability. Therefore on a smaller scale, shell availability may influence the number of settlers. Settlement periods of P. middendorffii and P. nigrofascia fully overlapped, so their larvae probably were affected by similar transport factors, such as current and tidal movement. Nevertheless they showed different spatial patterns of settlement.

Shell utilization patterns of a tropical intertidal hermit crab assemblage

The shell selection and utilization patterns of three sympatric hermit crab populations (Clibanarius antillensis, C. sclopetarius, and C. vittatus) and shell availability were studied in a tropical intertidal low energy area. Shell availability (except for C. antillensis) was low and the hermit crabs showed overlap in size (mainly C. sclopetarius and C. vittatus). The influence of shell availability and selection on shell use was dependent on crab species. Clibanarius antillensis used mainly shells of Cerithium atratum, the most available shell species, while Clibanarius sclopetarius and C. vittatus occupied shells with lower availability in the studied area such as Chicoreus senegalensis, Stramonita haemastoma, Leucozonia nassa and Cymatium parthenopeum. The three species selected different gastropod shells with only Clibanarius antillensis using almost exclusively its preferred shell species in nature. The relationship between shield length and the weight of the used shell was not dependent on crab species or shell species, indicating that the size (not species) of the shells defines what size (not species) of crabs will occupy them.

Desiccation tolerance of four sympatric tropical intertidal hermit crabs (Decapoda, Anomura)

This study describes and quantifies the air exposure tolerance of four sympatric hermit crabs (Pagurus criniticomis, Clibanarius antillensis, C. sclopetarius, and C. vittatus) in an intertidal area in southeastern Brazil. We report on survivorship, percentage and rate of weight and water loss until death, and overall body water content. The coexisting populations showed similar percentages of overall body water content and weight and water loss until death. Survivorship depended on crab size rather than species, and was positively correlated with crab size within each species (linear relationship) and with the size of all individuals of this hermit crab assemblage (exponential relationship). Each species had a characteristic rate of weight and water loss, indicating the existence of different physiological adaptations to resist desiccation. These differences were directly related to the species’ distribution patterns in the intertidal zone.

Patterns of shell utilization and selection in two sympatric hermit crabs (Anomura: Diogenidae) in south-eastern Brazil

The present study evaluated shell utilization and preference of two sympatric hermit crab species, Calcinus tibicen and Clibanarius antillensis, from Ilha Galheta de Dentro, Vitória Bay, south-eastern Brazil. Distribution of individuals and use and availability of shells were estimated in the field, where micro-habitat and shell partitioning were demonstrated between the two species of crabs. Calcinus occurred in higher numbers in the infralittoral fringe and shallow subtidal, while Clibanarius was found mainly in the midlittoral zone. The crabs used shells of different architectures and sizes. Calcinus used mainly globose and low spired shells (Tegula viridula and Cymatium parthenopeum), while Clibanarius utilized predominantly the elongated and high spired ones (mainly Cerithium atratum). Clibanarius used shells with smaller volume, weight, and aperture. Free access experiments were conducted in the laboratory and showed that Calcinus and Clibanarius had a high satisfaction rate, i.e. only 50% of the crabs exchanged their shells. From those that exchanged, they chose shells with higher internal volume than that used in the field, while shell weight did not present any increase. Clibanarius was found in shells closer to the preferred ones and in a very different proportion from shell availability, contrasting to Calcinus, which followed shell availability instead of their preferences. Shell internal volume was more important as a choice factor than the weight for both hermit crab species, showing that crabs optimized shell volume in relation to shell weight in the free access experiments.

Effects of shell and food availability on metamorphosis in the hermit crabs Pagurus hirsutiusculus (Dana) and Pagurus granosimanus (Stimpson)

The effects of shell and food availability on survival and duration of the megalopal stage of the sympatric intertidal hermit crabs Pagurus hirsutiusculus (Dana) and P. granosimanus (Stimpson) were examined. In both species, survival to the first juvenile crab stage in the laboratory was independent of food and shell availability. In P. hirsutiusculus, megalopal duration was also independent of food and shell availability, whereas the presence of a shell shortened the duration of the megalopal stage in P. granosimanus by slightly more than a day. P. granosimanus megalopae look longer to reach competency, but used shells more quickly and consistently, than did P. Hirsutiusculus megalopae. When P. granosimanus megalopae had a shell, the presence of food shortened megalopal duration, whereas when megalopae lacked a shell, food lengthened megalopal duration. This suggests that P. granosimanus megalopae may retain at least a limited ability to feed (although we were unable to directly observe feeding in either species). These observations are consistent with interspecific differences in adult shell-associated behaviors, and suggest that for P. granosimanus shells are more important to early postlarval survival, or more difficult for megalopae to obtain, than for P. hirsutiusculus. However, the delay capabilities of P. granosimanus are relatively trivial compared to other invertebrates, which suggests that pagurid megalopae generally have little trouble locating suitable shells.

An analysis of competitive interactions between 3 hermit crab species.

Competition for empty gastropod shells in a group of three sympatric hermit crabs (Pagurus hirsutiusculus, Pagurus granosimanus, and Pagurus beringanus) was studied in the San Juan Archipelago, Washington State. Estimates of the competitive effects of each species on the others' shell supplies were derived using field data on shell utilization and the results of laboratory experiments to determine rates of acquisition and exchange of shells and preferences for different shell species. Each species experienced approximately an order of magnitude more intraspecific competition than interspecific competition for empty shells. This resulted from differences in preference for shell shapes, shell size use, and habitat use between P. hirsutiusculus and P. granosimanus, and largely from differences in habitat use between P. beringanus and the other two species. Experiments involving the release and recensusing of marked empty shells were used to estimate competitive effects more directly for the interaction between P. hirsutiusculus and P. granosimanus. Results were consistent with the estimates derived from data on resource partitioning. Possible causes of the low levels of interspecific competition are discussed, and results are compared with studies of other organisms that estimated both inter- and intra-specific competition.