''Inachus phalangium'', or Leach's spider crab, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

s from the north-eastern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

. 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. He was one of River gods (Greek mythology), the three thousand sons of Oceanus and Tethys (mythology), Tethys. The In ...

''.

Description

Large males may reach a

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 unde ...

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 ep ...

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 . Description They are usually seen covered with sponge which they ap ...

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

Distribution

''Inachus phalangium'' is found in the eastern

, from

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

in the north to

West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

and the

Cape Verde Cape Verde or Cabo Verde, officially the Republic of Cabo Verde, is an island country and archipelagic state of West Africa in the central Atlantic Ocean, consisting of ten volcanic islands with a combined land area of about . These islands ...

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 constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

Anemonia sulcata ''Anemonia sulcata'', or Mediterranean snakelocks sea anemone, is a species of sea anemone in the family (biology), family Actiniidae from the Mediterranean Sea. Whether ''A. sulcata'' should be recognized as a Synonym (taxonomy), synonym of ''An ...

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

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

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 ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

' description of "''Cancer tribulus''" in the

12th edition 1 (one, unit, unity) is a number, numeral, and glyph. It is the first and smallest positive integer of the infinite sequence of natural numbers. This fundamental property has led to its unique uses in other fields, ranging from science to sp ...

of his ''

Systema Naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...

'' 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 ...

'', 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 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 ...

. The first valid description was

Johan Christian Fabricius Johann 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 co ...

' 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 something 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 ...

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

References

External links