Inachus phalangium
Encyclopedia
Inachus phalangium, Leach's spider crab, is a species
of crab
from the north-eastern Atlantic Ocean
and Mediterranean Sea
. It is up to 20.5 mm (0.807086614173228 in) wide, and is very similar to other species in the genus Inachus
.
size of 20.5 by 17.5 mm (0.807086614173228 by 0.688976377952756 ), and is brownish-yellow in colour. The carapace becomes narrower towards the front of the animal, and is often concealed by epibiont
s. I. phalangium resembles the closely related species Inachus dorsettensis, but has less prominent spines on the carapace.
, from Norway
in the north to West Africa
and the Cape Verde
islands in the south, and extending into the Mediterranean Sea
. It lives at depths of 11 metre.
with the sea anemone
Anemonia sulcata
(snakelocks anemone). The crab gains protection from potential predators 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.
of his Systema Naturae
in 1767. Linnaeus' description was, however, too vague to allow the species to be confidently identified. That name is therefore a nomen dubium
, and it was suppressed by the International Commission on Zoological Nomenclature
in 1964 at the request of Lipke Holthuis
. The first valid description was Johan Christian Fabricius
' publication of the name Cancer phalangium in his 1775 work Systema Entomologiae. The name Cancer phalangium was later protected by being placed on the Official List of Specific Names in Zoology.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
from the north-eastern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
. It is up to 20.5 mm (0.807086614173228 in) wide, and is very similar to other species in the genus Inachus
Inachus (crab)
Inachus is a genus of crab, containing the following species:*Inachus aguiarii Brito Capello, 1876*Inachus angolensis Capart, 1951*Inachus biceps Manning & Holthuis, 1981*Inachus communissimus Rizza, 1839...
.
Description
Large males may reach a carapaceCarapace
A carapace is a dorsal 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 underside is called the plastron.-Crustaceans:In crustaceans, the...
size of 20.5 by 17.5 mm (0.807086614173228 by 0.688976377952756 ), and is brownish-yellow in colour. The carapace becomes narrower towards the front of the animal, and is often concealed by epibiont
Epibiont
An epibiont is an organism that lives on the surface of another living organism. An epibiont is usually considered harmless to the host; in this sense, the relationship between the two organisms can be considered neutralistic or commensalistic. Typical epibionts are barnacles, remoras, and algae,...
s. I. phalangium resembles the closely related species Inachus dorsettensis, but has less prominent spines on the carapace.
Distribution
I. phalangium is found in the eastern Atlantic OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, from Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
in the north to West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
and the Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
islands in the south, and extending into the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
. It lives at depths of 11 metre.
Ecology
Inachus phalangium lives commensallyCommensalism
In ecology, commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral...
with the sea anemone
Sea anemone
Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
Anemonia sulcata
Snakelocks anemone
The snakelocks anemone is a sea anemone found in the eastern Atlantic ocean to the Mediterranean sea.The tentacles of anemones in deep or murky water can be a grey colour but are otherwise usually a deep green colour with purple tips. This is due to the presence of symbiotic algae within the...
(snakelocks anemone). The crab gains protection from potential predators 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' description of "Cancer tribulus" in the 12th edition12th edition of Systema Naturae
The 12th edition of was the last edition of to be overseen by its author, Carl Linnaeus. It was published in three volumes, with parts appearing from 1766 to 1768...
of his Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
in 1767. Linnaeus' description was, however, too vague to allow the species to be confidently identified. That name is therefore a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
, and it was suppressed by the International Commission on Zoological Nomenclature
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
in 1964 at the request of Lipke Holthuis
Lipke Holthuis
Lipke Bijdeley Holthuis was a Dutch carcinologist, considered one of the "undisputed greats" of carcinology, and "the greatest carcinologist of our time"....
. The first valid description was Johan Christian Fabricius
Johan Christian Fabricius
Johan Christian Fabricius was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others...
' publication of the name Cancer phalangium in his 1775 work Systema Entomologiae. The name Cancer phalangium was later protected by being placed on the Official List of Specific Names in Zoology.