Shell Utilization Patterns Research Articles

Profiling abundance, size, and shell utilization patterns ofCoenobita clypeatus(Fabricius, 1787) (Decapoda: Anomura: Coenobitidae) in protected and highly frequented beaches in Puerto Rico

AbstractThe coastal Caribbean is a well-known harbor for biodiversity, yet it is mainly valued for its ample resources and services. Economic interests typically supersede conservation efforts, introducing anthropogenic-related factors such as noise, chemical pollution, and geographical disturbances into the littoral zone, where ecological diversity is abundant. Although human activity is known to be detrimental to biodiversity across habitats, the effect of conservation measures that limit anthropogenic activity on coastal populations remains understudied. To measure the benefit of conservation in the littoral environment, we sampled populations of the hermit crab Coenobita clypeatus (Fabricius, 1787) of highly frequented (non-protected) and protected beaches in northern Puerto Rico. We profiled 1,119 individuals by using transects, describing their size and shell utilization patterns during winter and summer. The C. clypeatus population was larger (P < 0.0001 during both seasons) and more abundant (P = 0.0006 during winter, P < 0.0038 during summer) in the protected beach than in the non-protected beach, with no effect of season. Shell utilization patterns were more consistent in the protected beach, likely due to the greater availability of gastropod shells. These results suggest that the conservation measures implemented in the protected beach promote the survival, reproduction, and growth of hermit crabs in the location. Expansion of protected habitats through governmental and civilian efforts should enhance the conservation of the biodiversity of protected areas.

Patterns of shell utilization and preference in two sipunculan genera, Phascolion and Aspidosiphon

AbstractSipunculans are non-segmented marine worms with an anterior retractable introvert, which are commonly included in Annelida based on molecular phylogenetic and phylogenomic analyses. They generally burrow in the soft sediments or live inside the crevices of hard substrata (e.g. calcareous/coralline rocks). However, members of some sipunculan genera (mainly Phascolion and Aspidosiphon) are known to have a peculiar habit of dwelling in vacant shells of gastropods or scaphopods. In this study, we investigated the shell utilization and preference pattern of the species of Phascolion and Aspidosiphon in Japan. We collected 302 sipunculans, comprising 273 and 29 individuals in Phascolion and Aspidosiphon, respectively, from 57–800 m depth of three study sites in the Pacific coast of Honshu Island, Japan. The species of Phascolion were found in vacant shells of 38 genera of 27 families of gastropods and six genera of four families of scaphopods, whereas the species of Aspidosiphon were found in 11 genera of 11 families of gastropods and one genus of scaphopod. These results suggest that members of each genus use a wide range of gastropod and scaphopod shells. The body size of the sipunculans was positively correlated with the shell size, suggesting that they change the shells as they grow. Furthermore, we investigated the shell preference of Phascolion species by comparing morphological characteristics of shells occupied and unoccupied by sipunculans. Generalized linear mixed model (GLMM) analyses suggest that the species of Phascolion tend to use long and narrow shells. Such shells likely fit well the elongated trunk of sipunculans.

Shell utilization pattern of the Hermit crab Clibanarius rhabdodactylus Forest, 1953 on rocky shores of the Saurashtra coast, Gujarat State, India

Shell utilization pattern of the Hermit crab Clibanarius rhabdodactylus Forest, 1953 on rocky shores of the Saurashtra coast, Gujarat State, India

Shell utilization pattern by the hermit crab Diogenes custos (Fabricius, 1798) along Gulf of Kachchh, Gujarat, India

Present work aims to study the gastropod shell utilization pattern of hermit crab Diogenes custos in the intertidal zone of Gulf of Kachchh, Gujarat, India. Hermit crab specimens were collected randomly during the low tide timings using hand picking method in February 2019 and November 2019. Data on abundance of common gastropod species were also collected using a quadrate sampling method. Hermit crab wet weight (HW) and their shield length (SL) (represent the size of the hermit crabs) were measured. Gastropod shells were identified up to species level and different morphological characters such as shell dry weight (DW), shell length (SHL), shell volume (SHV), shell aperture length (SAL), and shell aperture width (SAW) were measured. Total 2000 individuals of D. Custos, 1171 males (58.6%), 763 females (38.1%) and 66 ovigerous females (3.3%) occupying 49 species of gastropods were collected. Pollia undosa (21.9%) was highly occupied by D. custos followed by Cantharus spiralis (14.5%), Tenguella granulata (9.9%), Chicoreus virgineus (6.45%), Cerithium caeruleum (6.05%) and Nassarius distortus (6.05%). Regression analysis carried out between D. custos morphological characters and gastropod shell morphological characters showed a strong relationship which suggests that shell architecture plays an important role in shell utilization pattern of Diogenes custos. The abundance of Pollia undosa was very high in the intertidal zone as compared to other commonly occupied gastropods species which also suggests that gastropod shell availability in the habitat also has pronounced effect on shell utilization pattern of D. custos.

An integrative approach-using field and laboratory data to characterize shell utilization and selection pattern by the hermit crab Pagurus criniticornis (Paguridae) from Anchieta Island, Brazil

The aim of this study was to characterize the pattern of gastropod shell occupation in the field and selection of shell size and type under laboratory conditions by the hermit crab Pagurus criniticornis (Dana, 1852), inhabiting the infralittoral area of Anchieta Island, Sao Paulo, Brazil. Hermit crabs were obtained monthly during 1999 by SCUBA diving. For experiments under laboratory conditions, samplings were performed in 2002. The hermit crabs occupied 16 species of gastropods shells. Cerithium atratum (Born, 1778) was the most occupied shell (89.31%), followed by Morula nodulosa (4.73%) (Adams, 1845). No difference was observed in the pattern of occupation between males and females. The equations that best demonstrated the relationship between hermit crabs and their shells were those that involved Shell Wet Weight (SWW) and Shell Internal Volume (SIV). The laboratory experiments were in accordance to the pattern of occupation observed in the field; the mean value of SAI (Shell Adequacy Index) recorded to the population studied was 1.13 with a trend to increase this value in the last size classes. The results obtained corroborate with the hypothesis of the occupation process of shells governed not only by availability of shells, but also by its architecture. In addition, the shell stock in the area is one another important condition related to the exhibited pattern of shell occupation by P. criniticornis, and allows the stable coexistence among the island assemblage. The pattern of occupation observed promotes a high reproductive profile for the population studied, maximizing the populational growth.

Gastropods shell utilization among hermit crabs targeted by bait fishers along a tropical mangrove fringed creek, Mida, Kenya

Mangrove gastropods and hermit crabs are frequently harvested for use as bait by artisanal trap and hook fishers, along the Kenyan coastline and elsewhere. In addition to mangrove degradation, the harvesting of shelled invertebrates, can alter shell availability and hence survival of these interdependent fauna. This study compares shell morphometric characteristics such as shell availability, adequacy and bait yield, among sites with different patterns of bait harvesting and other human disturbances. Shell morphometrics are also related to mangrove forest stand characteristics such as forest complexity, dominance, cutting intensity and sapling regeneration. Results indicate that the sampling regime, hermit crab taxa and mangrove zone influence morphometric characters of the gastropod and hermit crab. Significantly higher (P < 0.001) shell availability, adequacy and bait yield of the predominant hermit crab, Clibanarius danai, are recorded at upper and mid forested zones of sites with robust forest. This was attributed to shell selectivity of the crab, coupled with constancy of the environment at closed canopy sites. Apparently, forest structure is an important determinant of shell utilization patterns compared to prevailing bait harvesting activity. Protection of robust upper mangrove forest zones may therefore enhance sustainability of shelled bait harvesting and consequently the livelihoods support emanating from bait fishery.

Pattern of shell utilization in the hermit crabClibanarius zebra(Dana, 1852) along the Saurashtra coast, Gujarat, India

This study focuses on evaluating the pattern of shell utilization by the hermit crab Clibanarius zebra collected from the intertidal zone of four different sites along the Saurashtra coast, Gujarat, India. Specimens were collected monthly from March 2012 to August 2013 during low tide; hermit crab weight (HW) and their shield length (SL) were measured. Gastropod shells were identified and different morphological variables were recorded [dry weight (DW), shell length (SHL), shell aperture length, and shell aperture width]. A total of 804 hermit crabs occupying 23 gastropod species were collected. Cerithium scabridum (41.8%) was the shell most occupied by the crabs followed by Turbo intercostalis (10.6%), Astrea stellata (7.8%), Lunella coronata (6.6%), and Chicoreus brunneus (5.6%). Significant difference was obtained in the percentage of shell occupation between sexes. Regression analysis showed a high correlation between the different morphological variables of hermit crabs and gastropod shells; the highest values of correlation were obtained between HW and DW. The high values of correlation coefficient and regression models between the different morphological variables of hermit crabs and gastropod shells suggest that shell architecture has a huge impact on shell utilization pattern of C. zebra.

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 Utilization Pattern by the Hermit Crab Isocheles sawayai Forest and Saint Laurent, 1968 (Anomura, Diogenidae) from Margarita Island, Caribbean Sea, Venezuela

Isocheles sawayai is a hermit crab that is occasionally mentioned in the literature, and recently its distribution was extended to Venezuelan waters. Because no information on the biology and shell use patterns of this species inhabiting Caribbean waters is available, we provide the first information on shell occupation patterns of I. sawayai from Venezuela. Specimens were collected monthly from January to December 2000 along the sandy shore of Margarita Island, Venezuela. The 942 specimens collected showed different shell use patterns between the sexes and according to the reproductive condition of the females. The gastropods Leucozonia nassa (37.37%), Engoniophos unicinctus (25.37%), Nassarius vibex (4.88%), Melongena melongena (4.25%), and Stramonita haemastoma (3.82%) represent 76% of the total occupied shells. Of the total of 26 different shell species occupied by I. sawayai, males were found occupying 21, while females were found occupying all 26 shell species. In general, both sexes most frequently occupied L. nassa and E. unicinctus. However, the percentage of females occupying these shells was significantly higher than that of the males. Regression analyses showed the best correlation between crab size, shell aperture width, and shell internal volume. The current comparative investigation, in combination with other South Atlantic populations of I. sawayai, provided further evidence of shell use adaptation in hermit crabs from different areas, and increases our insight into shell use of shallow-water hermit crabs.

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.

Shell utilization pattern of the hermit crab Clibanarius vittatus (Crustacea, Anomura) in an estuary at São Vicente, State of São Paulo, Brazil

We evaluated the gastropod shell utilization pattern of the hermit crab Clibanarius vittatus (Bosc, 1802) at Pescadores Beach in São Vicente, State of São Paulo, Brazil. Specimens were collected monthly from May 2001 through April 2003, in the intertidal zone at low tide. The crabs were weighed and their carapace shield length measured. All gastropod shells were identified and had their shell biometric parameters (total length and aperture length) measured (mm) and weighed (g). A total of 2,344 hermit crabs (644 males, 1,594 females, 45 ovigerous females and 61 individuals in intersex), using 13 species of gastropod shells, were collected. Stramonita haemastoma (Linnaeus, 1767), Cymatium parthenopeum (Von Salis, 1793) and Achatina fulica (Bowdich, 1822) comprised over 98% of all the shells. Male and intersex crabs were significantly larger than the females. This size difference strongly influenced the shell utilization pattern, principally in A. fulica, which has the largest shell size, that was only used by males and intersexual individuals of C. vittatus. Cymatium parthenopeum was the only shell species that showed a high determinant coefficient in all the biometric correlations evaluated. The high abundance of S. haemastoma shells and a strong correlation between crab size and shell aperture length established by a significant determination coefficient, indicated that C. vittatus uses this species as the principal resource for shell occupation at Pescadores Beach.

Pattern of shell occupation by the hermit crab Pagurus exilis (Anomura, Paguridae) on the northern coast of São Paulo State, Brazil

The purpose of this study was to determine the shell occupation pattern of Pagurus exilis using the percentage of shell types that were occupied and the morphometric relationship between hermits and occupied shells. Specimens were collected monthly from July 2001 to June 2003. A total of 1737 individuals were collected, occupying 19 gastropod shell species. Buccinanops gradatum (82%) was the most occupied shell, followed by Natica isabelleana (6.4%), Stramonita haemastoma (3.2%), and Cymatium parthenopeum (2.2%). There was a differential shell utilization pattern between sexes; males occupied larger and heavier shells while the non‐ovigerous females occupied the lightest ones. Pagurus exilis occupied more bare shells instead of incrusted ones. Buccinanops gradatum was the most occupied shell species as a function of its availability in the survey, and this occupation is strongly associated with the higher internal volume presented by these shells.

Interference and exploitation components in interespecific competition between sympatric intertidal hermit crabs

This study was designed to evaluate the effect of interference and exploitation competition in shell partitioning between two hermit crab species ( Pagurus criniticornis and Clibanarius antillensis). Field samples revealed that shells of the gastropod Cerithium atratum were the main resource used by both hermit crab species and that Pagurus used eroded or damaged shells in higher frequency than Clibanarius. The exploitative ability of each species was compared between species in the laboratory using dead gastropod ( Cerithium) baits to simulate predation events and signalize newly available shells to hermit crabs. Pagurus reached the baits more rapidly than Clibanarius, but this higher exploitative ability did not explain shell utilization patterns in nature. Another experiment evaluated the dominance hierarchy between these two hermit crab species and revealed that Clibanarius was able to outcompete Pagurus for higher quality shells in agonistic encounters. This higher interference competitive ability of Clibanarius in relation to Pagurus may explain field observations. Nevertheless, Pagurus may be responsible to enhance shell availability to other hermit crab species that have lower ability to find and use newly available shells. Differently, the poorer condition of shells used by Pagurus, the higher ability of this species to attend gastropod predation events and its higher consumption rate by shell-breaking crabs ( Menippe nodifrons) may increase its predation risks, thus revealing the disadvantages of such an exploitative competitive strategy for hermit crabs.

Shell condition and adequacy of three sympatric intertidal hermit crab populations

Shell use in relation to size adequacy and presence of physical damage and encrustation was evaluated and compared among and within three co-existing species of intertidal hermit crab (Clibanarius antillensis, C. sclopetarius and C. vittatus) in the intertidal region of Pernambuco Islet, São Sebastião Channel, south-eastern Brazil. Comparisons of shell utilization patterns among species and sexes were made with respect to physical damage (perforations and breakage in aperture and apex), encrustation by other organisms and shell size adequacy. Two adequacy indices were calculated. The visual adequacy index (VAI) was based on the degree of hermit crab retraction into the shells (1 = crab totally retracted and 6 = shield exposed). The shell adequacy index (SAI) was calculated through a comparison of the weight of the used versus the preferred shell. A relationship was found between VAI and SAI with crabs assigned as VAI = 3 occupying optimal shells (SAI = 1), i.e. crabs that could retract and those that could not retract the whole body into shells were in relatively heavier and lighter shells than the preferred ones, respectively. Shells utilized by the hermit crabs were generally undamaged and highly encrusted (except for C. antillensis) by oysters, barnacles and green algae, features that may reduce the risks of desiccation and predation. The frequent damage to the shell apertures was associated with a high abundance of shell-crushing predators in the studied area. The degree of encrustation as well as the shell adequacy (VAI and SAI) showed intra- and interspecific variation, while the presence of damage differed only among sexes (reproductive classes). In general, the smallest individuals in the populations used relatively heavier shells. Fecundity of the crabs of this assemblage is thought not to be limited by shell use once ovigerous females are occupying optimal shells.

Hermit crab (Decapoda, Anomura) attraction to dead gastropod baits in an infralittoral algae bank

Hermit crabs use gastropod shells as shelter and are adapted to follow chemical cues released from tissues of dead or injured gastropods as a way to find new and more adequate shells. The species composition, crab size, shell types adequacy and physical condition were compared between attracted individuals and crabs collected in previous samples. The previous sampling was carried out in five areas before each experiment. Then, five baits of crushed gastropods in nylon net bags were installed in these areas. Three samples were taken at 30min intervals, capturing all crabs within a circle of 60cm diameter. Attraction of hermit crabs was tested for four different gastropod baits to verify specificity of the chemical cues. Clibanarius antillensis, Pagurus brevidactylus and Paguristes tortugae were collected in the study area. Pagurus brevidactylus, the smallest species, turned out to be more attracted than the 2 other species. The results showed that attracted crabs utilized more gastropod shell types than that collected in previous samples, however shell utilization pattern did not differ between them. Attracted animals were slightly smaller (shield length) than those collected in the previous samples but did not present significant differences in shell adequacy and condition. The four experimental baits attracted the crabs in similar ways not indicating a specific response from the crabs. The fact that attracted animals were smaller suggested that the attraction to dead gastropods might enable the acquisition of a new and larger shell and, consequently, chains of shell exchange between the attracted crabs.

SHELL UTILIZATION PATTERNS OF A TROPICAL ROCKY INTERTIDAL HERMIT CRAB ASSEMBLAGE: I. THE CASE OF GRANDE BEACH

Hermit crabs depend on gastropod shells that influence many characteristics of their life histories. The relationship between shell utilization patterns and biological attributes enables comparisons among populations and discussions of the influence of the environment (shell supply) on hermit crab biology. This study was undertaken in a cobble/boulder low slope rocky shore in Grande Beach, Sao Sebastiao, Sao Paulo State, Brazil. Crabs were randomly sampled, measured (shield length), and their sexes were determined. Shells were identified, sized (height, width, and aperture length), and weighed. Four hermit crab species were registered: Clibanarius antillensis, Paguristes tortugae, Pagurus criniticornis, and Calcinus tibicen. Shell use was influenced by shell availability, despite the selection of certain shell types and sizes by hermit crabs. Shells were not considered a limiting resource to this hermit crab assemblage, and shell availability was dependent on shell type and size as well as on individual size and species composition of the hermit crab assemblage (presence of competing species). Shell partitioning among crab species was recorded and associated with species coexistence in this area. Differential shell use was recorded among size and reproductive classes of C. antillensis. There was a tendency toward high numbers of ovigerous females in relatively lighter (smaller) and small-aperture shells, such as Cerithium atratum and Morula nodulosa, which was associated with growth restriction and low fecundity imposed by shell morphology.

SHELL UTILIZATION PATTERN OF THE HERMIT CRAB CALCINUS TIBICEN (DIOGENIDAE) FROM SOUTHERN BRAZIL

The purpose of this study was to determine the shell utilization pattern of Calcinus tibicen using the percentage of the different shell types that were occupied, the morphometric relationship between hermit crabs and occupied shells, as well as shell availability based on the empty shells and living gastropods observed. Specimens were collected at two-month intervals from January to November 1998 along the rocky shore of Praia Grande, Ubatuba, using a specific methodology adapted to the irregular surface of the area. Of 1,069 shells collected, empty shells were less frequent (4.11%) than shells occupied by either hermit crabs (23.11%) or living gastropods (72.78%). A total of 247 hermit crabs were captured occupying seven of the twelve shell species collected in the field. Only Stramonita haemastoma was occupied in significant numbers (71.26%). There was a differential shell utilization pattern between sexes; males were most abundant in S. haemastoma shells while the ovigerous females occupied Leucozonia nassa. Regression analysis showed a close correlation between the dimensions of the crabs and the utilized shells. In this study, shell occupation by C. tibicen varied as a function of shell type availability, with intraspecific differences in occupation patterns also occurring.

PATTERNS OF SHELL UTILIZATION IN PETROCHIRUS DIOGENES (DECAPODA, ANOMURA, DIOGENIDAE) IN THE UBATUBA REGION, SÃO PAULO, BRAZIL

The objective of this study is to investigate the patterns of shell utilization in Petrochirus diogenes in the Ubatuba region, SP, Brazil. Hermit crabs were obtained from 1993 to 1996 with the aid of a shrimp fishery boat equipped with two double-rigged trawling nets. Shells were identified and weighed, and their maximum aperture width was measured. Hermit crabs were weighed, and their shield length was recorded. A total of 634 P. diogenes specimens, occupying shells of 12 gastropod species, was obtained. The shells of Tonna galea, Zidona dufresnei and Strombus pugilis were the most frequently occupied, the first marked by its larger aperture width and lower average weight. Small hermit crabs inhabited a wide variety of gastropod shells due to their higher availability. However, the utilization of T. galea shells became predominant as the crabs attained larger sizes. Differences in weight and aperture width are known to encourage certain shell utilization patterns and may affect growth and reproduction of hermit crabs.

Patterns of Shell Utilization in Petrochirus Diogenes (Decapoda, Anomura, Diogenidae) in the Ubatuba Region, São Paulo, Brazil

The objective of this study is to investigate the patterns of shell utilization in Petrochirus diogenes in the Ubatuba region, SP, Brazil. Hermit crabs were obtained from 1993 to 1996 with the aid of a shrimp fishery boat equipped with two double-rigged trawling nets. Shells were identified and weighed, and their maximum aperture width was measured. Hermit crabs were weighed, and their shield length was recorded. A total of 634 P. diogenes specimens, occupying shells of 12 gastropod species, was obtained. The shells of Tonna galea, Zidona dufresnei and Strombus pugilis were the most frequently occupied, the first marked by its larger aperture width and lower average weight. Small hermit crabs inhabited a wide variety of gastropod shells due to their higher availability. However, the utilization of T. galea shells became predominant as the crabs attained larger sizes. Differences in weight and aperture width are known to encourage certain shell utilization patterns and may affect growth and reproduction of hermit crabs.

Distribution, reproduction and shell utilization patterns in three species of intertidal hermit crabs on a rocky shore on the Pacific coast of Japan

The spatial distribution, reproduction, and shell utilization patterns of three species of common intertidal hermit crabs Pagurus geminus McLaughlin, Pagurus lanuginosus De Haan and Clibanarius virescens (Krauss) on a rocky shore of Kominato, Boso Peninsula, Japan, are described. Although the distribution of each species greatly overlapped, Pagurus geminus mainly inhabited the middle intertidal zone, with Clibanarius virescens occupying a lower and Pagurus lanuginosus the lowest zone. This pattern was maintained over a 1-yr period with a few minor changes. Female Pagurus geminus generally inhabited a lower zone than males, ovigerous female Clibanarius virescens were distributed slightly lower than males, whereas a distinct sexual difference in the distribution was not seen in Pagurus lanuginosus. The ovigerous period of Pagurus geminus extended from October to August and is the longest reproductive season reported for a rocky intertidal decapod in Japanese waters. Pagurus lanuginosus became ovigerous from December to May and Clibanarius virescens, from April to December. The sex ratio was biased toward females in each case. Shell utilization patterns differed significantly between the three species, with Clibanarius virescens using the greatest variety of shells (33 species). Within species, sexual differences in shell utilization were seen in Pagurus geminus and Clibanarius virescens.