''Dorippe frascone'', the urchin crab or carrier crab, is a small species of crab in the family Dorippidae that was first described scientifically by J.F.W. Herbst, in 1785. It is found in the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

and parts of the western and eastern

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...

. It often has a symbiotic relationship with a long-spined sea urchin and carries one around on its carapace.

Description

The urchin crab is a brownish-pink colour and grows to a length of about . It has long-stalked eyes, a rounded carapace and long, slender legs. It uses only the first two pairs of legs for locomotion because the third and fourth pairs are used to grip a sea urchin which it carries around on its back. It is similar in

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

to the jellyfish crab ('' Ethusa'' spp.) but is easily distinguished by the different

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

transported. It also resembles decorator crabs but those actually stick living creatures such as

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throug ...

hydroids Hydroids are a life stage for most animals of the class Hydrozoa, small predators related to jellyfish. Some hydroids such as the freshwater '' Hydra'' are solitary, with the polyp attached directly to the substrate. When these produce buds ...

and

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...

ns, bits of algae and inert objects to their shells.

Distribution

''Dorippe frascone'' is found in the Red Sea and off the coast of East Africa, including

Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...

and

Cargados Carajos It is highly likely that the name Saint Brandon was derived from the French sailors and corsairs that sailed to and from Britanny, after a town called Saint-Brandan. It has since been Anglicised to Saint Brandon and is also known as the Cargad ...

, an atoll north east of

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label= Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It ...

Ecology

The urchin crab is so called because of its habit of carrying a sea urchin on its carapace. This is usually the red urchin ('' Astropyga radiata''), the black long-spined urchin ('' Diadema setosum'') or the banded diadem urchin ('' Diadema savignyi''). All these urchins have long, hollow spines and may provide protection to the crab by reducing the risk of

predation 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 ...

by fish while not being too heavy to carry. The urchin obtains benefit by being transported to new feeding grounds. Even large and mobile individuals submit passively to being carried in this way.

References

External links

* {{Taxonbar, from=Q5297873 Crabs Crustaceans described in 1785