''Liocarcinus marmoreus'', sometimes known as the marbled swimming crab, is a species of

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 ...

found in the northern Atlantic Ocean and North Sea. It may be found on sand and

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

in the sublittoral and lower littoral zones, down to a depth of , from the Azores and the

Alboran Sea The Alboran Sea (from Arabic , ''al-Baḥrān'') is the westernmost portion of the Mediterranean Sea, lying between the Iberian Peninsula and the north of Africa (Spain on the north and Morocco and Algeria on the south). The Strait of Gibraltar, w ...

(the westernmost section of the Mediterranean Sea) as far north as the

Shetland Islands Shetland, also called the Shetland Islands and formerly Zetland, is a subarctic archipelago in Scotland lying between Orkney, the Faroe Islands and Norway. It is the northernmost region of the United Kingdom. The islands lie about to the no ...

. It reaches 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 ...

length of , and is distinguished from other similar species by the presence of three similarly sized teeth on the edge of the carapace, between the eyes, and by the marbled colouration on the carapace. ''L. marmoreus'' is sometimes

parasitised Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

by the

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 eros ...

'' Sacculina''.

References

Portunoidea Crustaceans of the Atlantic Ocean Crustaceans described in 1814 {{crab-stub