''Inachus phalangium'', Leach's spider 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 ...

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

s from the north-eastern

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's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

and

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 ea ...

. It is up to wide, and is very similar to other species in the genus ''

Inachus In Greek mythology, Inachus, Inachos or Inakhos (Ancient Greek: Ἴναχος) was the first king of Argos, Peloponnese, Argos after whom a river was called Inachos (river), Inachus River,Bibliotheca (Pseudo-Apollodorus), Apollodorus2.1.1/ref> t ...

''.

Description

Large males may reach a

carapace A carapace is a Dorsum (biology), 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 tor ...

size of , and is brownish-yellow in colour. The carapace becomes narrower towards the front of the animal, and is often concealed by

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. ''I. phalangium'' resembles the closely related species ''

Inachus dorsettensis ''Inachus dorsettensis'', commonly known as the scorpion spider crab, is a species of crab generally found on loose substrates (stony bottoms to mud) from depth down to about . It is found along the east coast of the Atlantic Ocean from Norway t ...

'', but has less prominent spines on the carapace.

Distribution

''I. phalangium'' is found in the eastern

, from

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

in the north to

West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...

and the

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

islands in the south, and extending into the

. It lives at depths of .

Ecology

''Inachus phalangium'' lives commensally with the

sea anemone Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...

'' Anemonia sulcata'' (snakelocks anemone). The crab gains protection from potential

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s by sheltering beneath the anemone's stinging tentacles. The crab eats particles of food dropped by the sea anemone, and mucus from the surface of the anemone.

Taxonomy

The earliest scientific description of Leach's spider crab may have been

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, the ...

' description of "''Cancer tribulus''" in the 12th edition 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 nomen ...

'' in 1767. Linnaeus' description was, however, too vague to allow the species to be confidently identified. That name is therefore a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'', and it was suppressed by the

International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...

in 1964 at the request of

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

. The first valid description was

Johan Christian Fabricius Johan Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is cons ...

' publication of the name ''Cancer phalangium'' in his 1775 work ''Systema Entomologiae''. The name ''Cancer phalangium'' was later

protected Protection is any measure taken to guard a thing against damage caused by outside forces. Protection can be provided to physical objects, including organisms, to systems, and to intangible things like civil and political rights. Although th ...

by being placed on the ''Official List of Specific Names in Zoology''.

References

External links