''Calcinus verrillii'', commonly known as Verrill's hermit crab, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

hermit crab Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an as ...

in the genus ''

Calcinus ''Calcinus'' is a genus of hermit crabs in the family Diogenidae The Diogenidae are a family of hermit crabs, sometimes known as "left-handed hermit crabs" because in contrast to most other hermit crabs, its left chela (claw) is enlarged in ...

'' which is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

Bermuda ) , anthem = "God Save the King" , song_type = National song , song = "Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , es ...

. It was first described by the American zoologist Mary J. Rathbun and named in honour of the American zoologist

Addison Emery Verrill Addison Emery Verrill (February 9, 1839 – December 10, 1926) was an American invertebrate zoologist, museum curator and university professor. Life Verrill was born on February 9, 1839 in Greenwood, Maine, the son of George Washington Verrill ...

, who spent much time with his students studying the geology and marine fauna of Bermuda. Although this hermit crab species generally inhabits the discarded shell of a free-living gastropod mollusc, it sometimes makes use of the empty, tube-like shells of certain gastropod mollusc species while the tube is permanently cemented to rocks in the reef.

Description

Like other crabs in the genus ''

'', ''C. verrillii'' has a robust, calcified carapace, eight thoracic segments and six or seven abdominal segments. The carapace and legs are spotted with purple and orange, the eyes have slender eyestalks and the front three pairs of walking legs are smooth and hairless. The soft abdomen is coiled and fits into the mollusc shell which the hermit crab uses for protection, the

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

s at the tip of the abdomen gripping the inside of the shell.

Distribution and habitat

''Calcinus verrillii'' is native to Bermuda and does not occur naturally anywhere else. It is mostly found in the subtidal zone and has been found as deep as 110 metres (630 ft). It is uncommon in intertidal areas and rock pools but is abundant on reefs and rocks with strong water movement.

Ecology

As a hermit crab, ''Calcinus verrillii'' needs to find suitable empty shells of gastropod molluscs in which to live as it grows. It commonly inhabits shells of '' Cerithium litteratum'', but empty shells can sometimes be in short supply. On some occasions the hermit crab takes up abode in the calcified tube of the vermetid gastropod '' Spiroglyphus irregularis''. It also sometimes uses the tubes of the turritellids '' Vermicularia knorrii'' and '' Vermicularia spirata''. These tubes are normally attached to rocks, and when this is the case, the hermit crab no longer has freedom of movement to gather fragments of algae off the rock or

scavenge Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...

for its food. Instead the crab becomes a filter feeder. The advantages to the crab in making use of such a tube-like shell is that it is less likely to be swept off the rocks by strong water movements, and plenty of food may be brought to it by the current. Female ''C. verrillii'' grow larger than males, and are more likely to occupy tube shells.

References

External links

* {{Taxonbar, from=Q13448487 Hermit crabs Crustaceans described in 1901