Hermit Crab Species Research Articles

Competition is stronger between than within species in two coexisting hermit crab species

Both intra- and interspecific competition influence the partitioning of limited resources; the relative importance of each type of competition in resource distribution is influenced by several factors, including resource availability and population abundance. Several hermit crab species of the genera Calcinus and Clibanarius coexist, competing for the shells of the same gastropod species. The relative abundance of these species varies along the intertidal gradient, from a bias toward Clibanarius in the upper intertidal to a tendency toward Calcinus in the lower intertidal. We assessed the strength of intra- versus interspecific competition in Cli. albidigitus and Cal. californiensis by comparing the number of successful usurpations of preferred shells in single-species versus mixed-species trials. We performed these comparisons under four scenarios, varying the total individuals and their relative abundance (1.7:1, 1:1, or 1:1.7 ratio) to simulate demographic conditions along the intertidal gradient. There were more shell usurpations in mixed-species trials under all scenarios except for the 1:1 ratio at high total abundance. Calcinus californiensis usurped more shells than Cli. albidigitus in all mixed-species treatments, even in cases where Cli. albidigitus was more abundant. Our results show that interspecific competition is stronger than intraspecific competition, which could drive the competitive exclusion of Cli. albidigitus, the comparatively weaker species.

First evidence of a population of hermit crab Diogenes curvimanus (Clément, 1874) (Decapoda, Anomura, Diogenidae) on the Canary Islands

Abstract We report here for the first time the occurrence of the diogenid hermit crab species Diogenes curvimanus from the Canary Islands, which has been recorded previously from Atlantic European waters and the Mediterranean Sea. The species had been placed under the synonymy of D. pugilator until recently, and is the sole representative of Diogenes known from the islands. The specimens studied were observed between 2019 and 2023, suggesting that these could have recently settled into local habitats and developed a population capable of reproducing.

A new hermit crab species of the genus Catapaguroides A. Milne-Edwards & Bouvier, 1892 (Decapoda: Anomura: Paguridae) from Okinawa Island, southwestern Japan

Catapaguroides ngankeeae n. sp., a new diminutive species of Paguridae, is described from shallow reef environments in Okinawa Island, Ryukyu Islands, southwestern Japan. The new species is morphologically similar to C. brevidactylus Komai & Rahayu, 2013 and C. melini de Saint Laurent, 1968, but is distinguished from the two species primarily by the ornamentation of the palm and dactylus of the right cheliped and the length of the right sexual tube in the male. Catapaguroides ngankeeae n. sp. represents the eleventh species of the genus from Japanese waters.

HERMIT CRABS (CRUSTACEA: DECAPODA: ANOMURA) IN ADEN COASTS AT THE GULF OF ADEN WITH A NEW RECORD

The information on the hermit crab diversity on the northern shore of the Gulf of Aden is very limited and almost completely unknown. This study aims to record the hermit crab species in different habitats in Aden coasts at Gulf of Aden. The specimens were collected from 7 sites, by hand, and snorkelling up to 3 m depth, during the period time October 2020- October 2022. In this study, 10 hermit crab species were recorded belonging to 3 families (Coenobitidae, Diogenidae, Parapaguridae) belonging to 6 genera. One of these species represents the first records in the Gulf of Aden (Dardanus lagopodes (Forskål, 1775)). The dominant hermit crab on sandy shores was Coenobita scaevola (Forskål, 1775), while the dominant hermit crab in rocky shores was Clibanarius signatus Heller, 1861.

Seeing across variable ecological and social environments: comparative eye morphology of marine and terrestrial hermit crabs (Decapoda: Anomura: Coenobitidae, Paguridae)

Abstract Vision is a ubiquitous sensory modality adapted to vastly different environments, which place variable selection pressures on both macro- and microscopic dimensions of external eye morphology. The hermit crab clade (Crustacea: Decapoda: Anomura) spans environments from sea to land, yet, no systematic comparisons in eye morphology have been made between any species. We compared three species of hermit crabs inhabiting different ecological and social environments: two terrestrial species, one of which (Coenobita compressusH. Milne Edwards, 1837) is highly social and inhabits a flat, open diurnal habitat, and another (C. clypeatus Herbst, 1791) is its sister species that inhabits a rugged forested nocturnal habitat; and a third (Pagurus longicarpusSay, 1817) inhabits a marine intertidal habitat and is less social. We compared macroscopic eye morphology between species as well as microscopic differences in ommatidium-facet density and diameter within eyes. We found that eye dimensions (length, width, and thickness), but not overall volume, differed significantly between marine and terrestrial species. Furthermore, the highly social C. compressus had a significantly larger eye volume compared to its sister species, C. clypeatus, which is not as social. Larger eyes in C. compressus might be linked to its social lifestyle, where vision has been shown to be critical to finding conspecifics. All three species had a higher density of facets in the ventral compared to dorsal region of the eye. Our comparisons of external eye morphology revealed microscopic similarities but notable macroscopic variation between species, thus laying a foundation for future phylogenetically controlled tests within this species-rich clade, including comparisons of internal eye morphology.

A new species of hermit crab genus Diogenes Dana, 1851 from Papua, Indonesia (Crustacea, Decapoda, Anomura, Diogenidae)

A new species of hermit crab from the genus Diogenes Dana, 1851 is described on the basis of a specimen from Papua, Indonesia. Diogenes hawisi n. sp. is distinguished from the closest allied species, D. edwardsii (De Haan, 1849) and D. laevicarpus Rahayu, 1996, by the shape and armature of the left cheliped. Morphological differences of these three species are also supported by genetic analysis, through DNA barcoding using the CO1 gene marker.

A new species of the genus Trichopagurus de Saint Laurent, 1968 (Crustacea: Decapoda: Anomura: Paguridae) from a semi-submerged marine cave in Okinawa Island, southwestern Japan.

A new hermit crab species of Paguridae, Trichopagurus spinibrachium n. sp., is described on the basis of a single male specimen collected from the anchialine environment of a semi-submerged marine cave in Okinawa Island, Ryukyu Islands, southwestern Japan. It is morphologically similar to T. macrochela Komai & Osawa, 2005 and T. tenuidactylus Komai, 2013, but differs in the shape and armature of the ocular, antennular and antennal peduncles, chelipeds, and ambulatory legs. The new species may be distinguished from all known congeners by the stronger armature of the carpi and meri of both chelipeds. Trichopagurus spinibrachium n. sp. is the third species of the genus recorded from submarine caves, although it may also occur on nearby coral reefs as does T. macrochela and T. trichophthalmus (Forest, 1954).

A new species of hermit crab in the genus Strigopagurus Forest, 1995 (Crustacea: Anomura: Diogenidae) from the continental shelf off south-east Queensland, Australia

A new species of hermit crab, Strigopagurus fragarchela, is described from the continental shelf off south‑east (SE) Queensland. It can be separated from congeneric species by characters such as chelae (claw) shape, armature, and stridulatory plates; pereiopod shape and armature; and characteristic live colouration. Four endemic species are now known from Australia. A key is provided to all six species in the genus, and all are illustrated for easy comparison. New records of S. bilineatus Forest, 1995, are recorded, increasing its known southerly distribution.

Observation of air-exposure behaviour in the reef hermit crab, Calcinus elegans (H. Milne Edwards, 1836) (Decapoda, Diogenidae)

Abstract Many species of hermit crabs, such as Calcinus and Clibanarius spp., live on the rocky shores of tropical and warm temperate regions. During low tides, some of these species climb out of the tidal pools onto rock surfaces exposed to the air. In the genus Calcinus, however, such ‘Air-exposure (AE) behaviour’ was only known previously from Calcinus laevimanus. During a field study of the hermit crab fauna on Amami Oshima Island, Kagoshima, Japan, the AE behaviour of Calcinus elegans (Decapoda, Diogenidae) was observed on rocky shores. Moreover, the repeatability of the AE behaviour was confirmed. Therefore, we documented the AE behaviour of C. elegans as a second record of AE behaviour among Calcinus species by providing videographic evidence. The findings indicate that the AE behaviour has evolved in a broader range of Calcinus species than was previously assumed.

Thermal threshold and interspecific competition help explain intertidal hermit crab assemblages

Habitat heterogeneity promotes species diversity by providing a variety of abiotic and biotic conditions, whose impact on performance varies among species. Then, mobile species would be expected to move to areas whose conditions maximize their fitness. However, biotic pressures such as interspecific competition can push subordinate species into suboptimal areas, impeding this matching. The tropical hermit crab Clibanarius albidigitus occupies mostly upper intertidal sites where they can experience extreme environmental conditions. Meanwhile, its stronger agonistic competitor, Calcinus californiensis, mostly inhabits more moderate conditions at the mid intertidal. We estimated the avoidance threshold of the two hermit crab species to increasing water temperatures to help explain their intertidal distribution. We also compared the avoidance threshold of Cli. albidigitus to rising temperatures when presented alone and in the presence of chemical cues of its competitor to assess potential competitive niche exclusion. The avoidance threshold was measured in experimental tanks with a ramp that led from the water to an air-exposed platform; the threshold was defined as the temperature at which individuals emerged and remained air-exposed. Clibanarius albidigitus emerged at a higher temperature than its competitor, showing a higher thermal tolerance and potentially explaining its distribution in the upper intertidal. In the presence of Cal. californiensis, Cli. albidigitus emerged at lower temperature than when alone, likely as a strategy to reduce competition with stronger agonistic competitors, even at the cost of coping with harsh conditions. Our results support the hypothesis that competitive habitat exclusion contributes to explaining hermit crab assemblages.

Diversity and distribution of crustaceans in the mangrove forest of Nusa Lembongan, Bali, Indonesia

Abstract. Ginantra IK, Muksin IK, Joni M, Wijaya IMS. 2023. Diversity and distribution of crustaceans in the mangrove forest of Nusa Lembongan, Bali, Indonesia. Biodiversitas 24: 4533-4541. Research on the diversity and distribution of crustaceans in the mangrove forest of Nusa Lembongan, Bali, Indonesia was conducted from March to June 2022. Sampling was carried out using the quadratic method at seven mangrove forest sites. The identification of crustacean species is based on morphological characteristics, namely carapace color, claw shape, legs, and body size. Crustacean density was determined based on the number of individuals per unit area of mangrove forest, diversity was determined by the Shanon-Wiener Index, and crustacean distribution was determined based on the frequency of species presence in each square at the seven study sites. Environmental factors were also measured: Mangrove vegetation, substrate type, temperature, pH, and salinity. The results showed that 12 species of crustaceans were found, consisting of 10 species of crabs and two species of hermit crabs. Several species of crabs are quite dominant in the mangroves of Nusa Lembongan namely Sesarma pictum (De Haan, 1835), with a density of 7 individuals/5 m2, Uca tetragonon (Herbst, 1790) of 3.7 individuals/5 m2, Uca rosea (Tweedie, 1837) with a density of 2.5 individuals/ 5 m2, and Uca triangularis (A. Milne-Edwards, 1873) with a density of 2 individuals/5 m2. Environmental factors support the life of Nusa Lembongan crustaceans, namely the type of substrate, mostly muddy and sandy, diverse species of mangrove plants, both true and associated mangroves, water temperature 27.70-29.00°C, pH 6.88-7.15 and water salinity ranging from 27.83-31.53‰. Crustacean diversity is included in the moderate category with their diversity index. There are three crab species with moderate to frequent (absolute) frequency of presence, namely U. rosea (Fi: 57.15%), S. pictum (Fi: 71.43%), and U. tetragonon (Fi: 85.71%). These species are present in four to six mangrove forest sites.

Grazing activity of Clibanarius corallinus (H. Milne Edwards, 1848) (Decapoda: Anomura: Diogenidae) on epilithic algae in Australian coral reefs

Abstract Following an incidental observation of captive Clibanarius corallinus (H. Milne Edwards, 1848) supposedly removing algae from each other’s shells, we conducted a feeding experiment over 72 hours to understand its potential role as a mesograzer in coral reef ecosystems. Epiphyte-covered, coral rubble fragments of Acropora spp. were exposed to hermit crab (N = 41) activity for 72 h in a flow-through seawater aquarium system at Heron Island, southern Great Barrier Reef, Australia to understand whether hermit crabs could remove epilithic algae and if so, to what extent. Coral fragments exposed to the hermit crabs had 9.1% less chlorophyll at the end of the experiment. The detritus generated in the experimental set-up had 2.4 times more chlorophyll and 33.4% less organic biomass than the detritus generated in the control environment. The crabs did on average lose 0.11 g of their initial weight, which could have been a consequence of the experimental set-up. These results suggest that C. corallinus has the potential to contribute to the control of epilithic algae in coral reefs, with such effect having hitherto been overlooked as a result of the cryptic behaviour of this hermit crab species.

Latitudinal variation in reproductive performance of hermit crabs (Anomura: Paguroidea) in two marine provinces along the Brazilian coast

ABSTRACT We performed a comparative analysis of fecundity and reproductive effort of two hermit crab species, Clibanarius antillensis and Calcinus tibicen, distributed along the two marine provinces in Brazilian coast. Samples of both species were manually collected during spring low tides on a two-month basis, from February 2011 to January 2012 at locations separated by ~ 3000 km: North-eastern (NE) region – Pedra Rachada Beach (Ceará); South-eastern (SE) region – Araçá Beach and Grande Beach (São Paulo). The size of ovigerous females, as well as the fecundity values, egg volume, internal volume of occupied shells, and reproductive effort were analysed, and the results evidenced significantly higher values for females of both species collected in SE localities. In females collected NE, there was also the presence of aberrant eggs, which influenced the reproductive parameters analysed for these species, resulting in lower reproductive effort. Biomass invested in egg production varied between populations, but ovigerous females of SE invested a higher percentage of their weight in the production of its egg mass, showing significant differences in the reproductive effort. Variation in reproductive performance detected for both species may be related to latitudinal location and associated to the habitat’s characteristics.

Pola Persebaran dan Keanekaragaman Kelomang di Zona Litoral Pantai Leuweung Sancang Kabupaten Garut

The littoral zone of Leuweung Sancang Beach, Garut Regency has very diverse biodiversity, such as hermit crabs. This study aims to determine the distribution patterns and species diversity of hermit crabs in the littoral zone of Leuweung Sancang Beach. This research was conducted from February 2022 to June 2022. This research uses quantitative methods and sampling techniques using a 100 meter transect belt which is divided into 100 plots with a size of 1 x 1 meter. The stations used are Cibako 1 station, Cikujang Jambe 2 station, and Ciporeang 3 station. The results of this study obtained data on the distribution pattern of hermit crabs on Leuweung Sancang Beach, namely clusters with an id value > 1 obtained data on the diversity of hermit crabs consisting of 3 family, 5 genus, and 13 species. The results of the calculation of the ecological index on hermit crabs show that the average density of hermit crab species is 15.73 ind/m2, the average diversity index is 1.27 includes the moderate diversity category, the average uniformity index is 0.52 includes the moderate uniformity category, and the average dominance index is 0.39 includes the category of moderate dominance.

Seasonal variation in the land hermit crab, Coenobita rugosus H. Milne Edwards, 1837 (Decapoda, Anomura) and a preliminary study of land hermit crabs as a bioindicator of turtle nesting at Penghu County Wang-An Island green turtle nesting refuge, Taiwan

Abstract The present study surveyed the land hermit crab species, body size, shell type, and shell suitability, at five sites over four seasons in the Penghu County Wang-an Island Green Turtle Nesting Refuge. Coenobita rugosus H. Milne Edwards, 1837 was the only species recorded and found at three sites (Tiantai Hill, Xi’an Reservoir, and Tudigong). The density index of hermit crabs exhibited notable variations across the sites, showing no significant variation with the changing seasons. The bush habitat displayed a higher density index compared to the sand habitat. Additionally, the sites differed significantly in terms of the shell type and body size of the hermit crabs. Further, no significant relationship was established between abundance and weather factors or between crab abundance and sea turtle nesting. This investigation is a preliminary examination of the possibility of land hermit crabs being used as bioindicators for breeding of sea turtles.

Polarization vision in terrestrial hermit crabs.

Polarization vision is used by a wide range of animals for navigating, orienting, and detecting objects or areas of interest. Shallow marine and semi-terrestrial crustaceans are particularly well known for their abilities to detect predator-like or conspecific-like objects based on their polarization properties. On land, some terrestrial invertebrates use polarization vision for detecting suitable habitats, oviposition sites or conspecifics, but examples of threat detection in the polarization domain are less well known. To test whether this also applies to crustaceans that have evolved to occupy terrestrial habitats, we determined the sensitivity of two species of land and one species of marine hermit crab to predator-like visual stimuli varying in the degree of polarization. All three species showed an ability to detect these cues based on polarization contrasts alone. One terrestrial species, Coenobita rugosus, showed an increased sensitivity to objects with a higher degree of polarization than the background. This is the inverse of most animals studied to date, suggesting that the ecological drivers for polarization vision may be different in the terrestrial environment.

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

Description of unique live colour patterns as a tool for discriminating hermit crab species in the Iberian Peninsula

The unique colour patterns of the hermit crab species inhabiting the Iberian Peninsula and geographically close areas are studied based on colour patterns observed in live specimens either in the field or live in the laboratory. Live colour patterns are shown to be useful for differentiating species in the Paguroidea from Iberian waters. Colour information has not been frequently documented in previous studies, mainly because of difficulties in accessing live specimens. Up to 51 species are currently recorded within the study area, 45 of which are included in the present work, focusing on the distinctive colour traits for each species that can be observed in the field. A complete key for identifying the species within the study area based on colour patterns is included. This study is the first attempt to put in place this type of tool oriented to field work. Further studies will be required to complete and update this information, especially for species which are scarce or difficult to observe alive.

The Complete Mitochondrial Genome of the Hermit Crab Diogenes edwardsii (Anomura: Diogenidae) and Phylogenetic Relationships within Infraorder Anomura.

A complete mitochondrial genome (mitogenome) can provide important information for gene rearrangement, molecular evolution and phylogenetic analysis. Currently, only a few mitogenomes of hermit crabs (superfamily Paguridae) in the infraorder Anomura have been reported. This study reports the first complete mitogenome of the hermit crab Diogenes edwardsii assembled using high-throughput sequencing. The mitogenome of Diogenes edwardsii is 19,858 bp in length and comprises 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. There are 28 and six genes observed on the heavy and light strands, respectively. The genome composition was highly A + T biased (72.16%), and exhibited a negative AT-skew (-0.110) and positive GC-skew (0.233). Phylogenetic analyses based on the nucleotide dataset of 16 Anomura species indicated that D. edwardsii was closest related to Clibanarius infraspinatus in the same family, Diogenidae. Positive selection analysis showed that two residues located in cox1 and cox2 were identified as positively selected sites with high BEB value (>95%), indicating that these two genes are under positive selection pressure. This is the first complete mitogenome of the genus Diogenes, and this finding helps us to represent a new genomic resource for hermit crab species and provide data for further evolutionary status of Diogenidae in Anomura.

New hermit crab species (Anomura, Paguroidea) from the upper Miocene St. Marys Formation of Maryland (USA), preserved in their host shells

Two new species of hermit crab are recorded from the upper Miocene (Tortonian) St. Marys Formation of Maryland, named Pagurus hazenorum n. sp. and Paguristes timoni n. sp. and assigned to the families Paguridae Latreille, 1802, and Annuntidiogenidae Fraaije, 2014, respectively. Both new species are morphologically close to present-day congeners, but can be differentiated on details of ornament (tubercles, granules and teeth).