''Calcinus tubularis'' is a species of

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 a ...

. It is found in the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

and around islands in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...

, where it lives below the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

. Its carapace, eyestalks and claws are marked with numerous red spots. ''C. tubularis'' and its

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

, '' C. verrilli'', are the only hermit crabs known to show

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

in shell choice, with males using normal

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod shell The gastropod shell is part of the body of a Gastropoda, gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium s ...

s, while females use shells of gastropods in the family

Vermetidae The Vermetidae, the worm snails or worm shells, are a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Littorinimorpha. The shells of species in the family Vermetidae are extremely irregular, and ...

, which are attached to rocks or other hard substrates.

Distribution

The genus ''Calcinus'' has its

centre of diversity A center of origin is a geographical area where a group of organisms, either domesticated or wild, first developed its distinctive properties. They are also considered centers of diversity. Centers of origin were first identified in 1924 by N ...

in the central

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

, and only two species occur in the north-eastern Atlantic – ''

Calcinus paradoxus ''Calcinus'' is a genus of hermit crabs in the family Diogenidae, containing the following species: *'' Calcinus albengai'' Poupin & Lemaitre, 2003 *''Calcinus anani'' Poupin & McLaughlin, 1998 *''Calcinus argus'' Wooster, 1984 *''Calcinus ca ...

'' and ''Calcinus tubularis''. ''C. tubularis'' is a chiefly Mediterranean species; its

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

extends from

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

in the west to

Lebanon Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon () or the Lebanese Republic, is a country in Western Asia. It is located between Syria to Lebanon–Syria border, the north and east and Israel to Blue ...

in the east, with outlying records from

, the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Mo ...

Cape Verde , national_anthem = () , official_languages = Portuguese , national_languages = Cape Verdean Creole , capital = Praia , coordinates = , largest_city = capital , demonym ...

and

Ascension Island Ascension Island is an isolated volcanic island, 7°56′ south of the Equator in the South Atlantic Ocean. It is about from the coast of Africa and from the coast of South America. It is governed as part of the British Overseas Territory o ...

. Although it is distinctively coloured, the sedentary behaviour of ''C. tubularis'' allows

epibiont An epibiont (from the Ancient Greek meaning "living on top of") is an organism that lives on the surface of another living organism, called the basibiont ("living underneath"). The interaction between the two organisms is called epibiosis. An epi ...

s to colonise its shells, providing excellent

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

, and it can easily go unnoticed; it was first reported on the coast of the

Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Port ...

mainland in 2011, but is thought to have been living there for a long time.

Description

The

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the und ...

of ''Calcinus tubularis'' is bluish, with many red spots, and extends forwards as a short, triangular

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ships * Ros ...

. The

eyestalk In anatomy, an eyestalk (sometimes spelled eye stalk and also known as an ommatophore) is a protrusion that extends an eye away from the body, giving the eye a better field of view. It is a common feature in nature and frequently appears in fic ...

s are white with similar red spotting, as is the last segment of each of the walking legs, and both the fixed and movable fingers of the

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tars ...

s. The colour scheme exists in a dark form and a light form, which appears to be linked to

, particularly for females. ''C. tubularis'' is of "normal size" for a ''Calcinus'' species, frequently exceeding a carapace width of .

Ecology

''Calcinus tubularis'' is a rare species, found below the

. It is one of only two species of hermit crab (the other being the closely related '' C. verrilli'') in which

in shell use has been observed. Males inhabit

s, chiefly those of ''

Pisania maculosa ''Pisania'' is a genus of marine whelk in the family Pisaniidae. Some species prey on barnacles. Species According to the World Register of Marine Species (WoRMS) species with accepted names within the genus ''Pisania'' include: * '' Pisania an ...

'' or ''

Cerithium vulgatum ''Cerithium vulgatum'' is a species of sea snail, a marine gastropod mollusk in the family Cerithiidae. Description Distribution This species occurs in European waters and in the Mediterranean Sea The Mediterranean Sea is a sea connecte ...

'', which they can move freely; females occupy the fixed tubes made by the vermetid snail '' Lementina arenaria''. The only

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

known to attack ''Calcinus tubularis'' is a

rhizocephala Rhizocephala are derived barnacles that parasitise mostly decapod crustaceans, but can also infest Peracarida, mantis shrimps and thoracican barnacles, and are found from the deep ocean to freshwater. Together with their sister groups Thoraci ...

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive ...

, probably of the genus '' Septosaccus'', although it is also targeted by another barnacle, '' Trypetesa lampas'', which is an

egg predator Egg predation is a feeding strategy in many groups of animals (ovivores) in which they consume eggs. Since an egg represents a complete organism at one stage of its life cycle, eating an egg is a form of predation, the killing of another organism ...

of various hermit crabs.

Taxonomy

''Calcinus tubularis'' was first described by

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...

in the 1767

12th edition 1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. ...

of his ''

Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nom ...

'', under the name ''Cancer tubularis''. It was later described by Polydore Roux as ''Pagurus ornatus'', and that species was transferred to the genus ''

Calcinus ''Calcinus'' is a genus of hermit crabs in the family Diogenidae, containing the following species: *'' Calcinus albengai'' Poupin & Lemaitre, 2003 *''Calcinus anani'' Poupin & McLaughlin, 1998 *'' Calcinus argus'' Wooster, 1984 *'' Calcinus cal ...

'' in 1892 by

Édouard Chevreux Édouard Chevreux (10 November 1846, in Paris – 10 January 1931, in Bône) was a French carcinologist. Chevreux specialised in the study of Amphipoda, an order of malacostracan crustaceans. With Jean-Louis Fage (1883–1964), he was co-author of ...

and

Eugène Louis Bouvier Eugène Louis Bouvier (9 April 1856, in Saint-Laurent-en-Grandvaux – 14 January 1944, in Paris) was a French entomologist and carcinologist. Bouvier was a professor at the Muséum national d'histoire naturelle. Biography Following graduation at ...

Lipke Holthuis Lipke Bijdeley Holthuis (21 April 1921 – 7 March 2008) was a Dutch carcinologist, considered one of the "undisputed greats" of carcinology, and "the greatest carcinologist of our time". Holthuis was born in Probolinggo, East Java and obtained ...

recognised that ''C. ornatus'' was a junior synonym of ''Cancer tubularis'', and transferred Linnaeus' species to the genus ''Calcinus'', at which point it reached its current scientific name. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

' refers to the animals habit of living in the tubes of vermetid molluscs. Linnaeus' description is imprecise, and could refer to "practically any hermit crab", but the

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

(the Mediterranean Sea), together with the statement that it lives in worm tubes, restricts the possibilities to this one species.

Evolution

The

of ''Calcinus tubularis'' is '' C. verrilli'', 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 els ...

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 = , ...

. The two species show the same sexual dimorphism in shell choice, making this an example of niche conservatism.

References

{{Taxonbar, from=Q5018784 Hermit crabs Crustaceans of the Atlantic Ocean Crustaceans described in 1767 Taxa named by Carl Linnaeus