''Zebrida adamsii'' is a distinctively striped

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 ...

of crab that lives in association with a sea urchin in the Indo-Pacific region. It is cryptically coloured with vertical stripes and has special adaptations to its legs to enable it to cling to its host's spines.

Description

''Z. adamsii'' is a small crab, described as "a torpid, though elegant little crustacean" by the English naturalist Arthur Adams when it was first discovered by him and the Scottish zoologist Adam White during the surveying voyage of HMS ''Samarang'' in the Far East between 1843 and 1846. The carapace and limbs are smooth and hairless and are adorned with long spines. The colour is pink with dark, reddish-brown vertical stripes.

Distribution

''Z. adamsii'' has a wide distribution in shallow water in the tropical Indian Ocean and western Pacific Ocean. The type locality is the estuary of the Pantai River in Borneo at a depth of about .

Ecology

''Z. adamsii'' lives in symbiosis with a sea urchin, living among its spines. Sea urchins on which it has been found include '' Asthenosoma ijimai'', ''

Diadema setosum ''Diadema setosum'' is a species of long-spined sea urchin belonging to the family Diadematidae. It is a typical sea urchin, with extremely long, hollow spines that are mildly venomous. ''D. setosum'' differs from other '' Diadema'' with five, ...

'', '' Heliocidaris crassispina'', '' Pseudocentrotus depressus'', '' Salmacis bicolor'', '' Salmacis virgulata'', '' Toxopneustes elegans'', ''

Toxopneustes pileolus ''Toxopneustes pileolus'', commonly known as the flower urchin, is a widespread and commonly encountered species of sea urchin from the Indo-West Pacific. It is considered highly dangerous, as it is capable of delivering extremely painful and m ...

'', ''

Tripneustes gratilla ''Tripneustes gratilla'', the collector urchin, is a species of sea urchin. Collector urchins are found at depths of in the waters of the Indo-Pacific, Hawaii, the Red Sea, and The Bahamas. They can reach in size. Description Collector urch ...

'' and a species of '' Acanthocidaris''. Adaptations for this lifestyle include a specialist joint between the propodus and dactylus on the walking legs enabling the crab to cling to its

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

, and cryptic colouring in the form of vertical stripes. Females are slightly larger than males and usually live singly on a sea urchin while males move from one urchin to another searching for females. ''Z. adamsii'' feeds on its host's

tube feet Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on br ...

and on the epidermal tissue covering the

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...

and the base of the spines. This does little harm to the host which readily regenerates both the tissue and the tube feet. ''Z. adamsii'' larvae are

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

ic and pass through four

zoea Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...

l stages, and one

megalopa Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...

stage before settling on the seabed and undergoing metamorphosis into juvenile crabs.

References

External links

* * {{Taxonbar, from=Q7938094 Pilumnoidea Crustaceans of the Indian Ocean Crustaceans of the Pacific Ocean Crustaceans described in 1847 Taxa named by Adam White (zoologist)