Leptasterias hexactis
| Leptasterias hexactis | |
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| Leptasterias hexactis | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Forcipulatida |
| Family: | Asteriidae |
| Genus: | Leptasterias |
| Species: | L. hexactis |
| Binomial name | |
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Leptasterias hexactis (Stimpson, 1862) |
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Leptasterias hexactis is a species of starfish in the family Asteriidae, commonly known as the six-rayed star. It is found in the intertidal zone of the western seaboard of the United States. It is a predator and is unusual among starfish in that it broods its eggs and young.
Leptasterias hexactis forms part of a species complex. Over the years, various authorities have discussed the phylogenetic relationships of L. epichlora, L. aequalis and L. hexactis, all species of Leptasterias found in the north west Pacific Ocean. The authorities were Bush (1918), Fisher (1930), Chia (1966), Kwast (1990) and Stickle (1992). More recent morphological and behavioural studies have resulted, according to the World Register of Marine Species (WoRMS) in the retention of a single species, L. hexactis, with the other two being considered synonyms. WoRMS now recognizes three subspecies, L. hexactis hexactis (Stimpson, 1862) L. hexactis occidentalis Djakonov, 1938 and L. hexactis vancouveri (Perrier, 1875).
Leptasterias hexactis is a rather squat starfish growing to a diameter of about 5 centimetres (2.0 in) with 6 short, broad arms. These are about as long as the disc is wide. The colour of the aboral (upper) surface varies, usually being a plain or mottled dark grey, brown or olive green colour or occasionally brick red. It is densely clad with short, mushroom-shaped spines, interspersed among which are pedicellariae (small, two-jawed pincers). The central row of spines on each arm is distinctive. The oral (under) surface is a pale colour with parallel rows of tube feet with suckers extending along the arms.
In California Leptasterias hexactis might be confused with Leptasterias pusilla but that species is smaller, is usually a pale grey-brown or reddish colour and has elongated, thinner arms and sharp spines.
Leptasterias hexactis occurs in the intertidal zone of the north east Pacific Ocean with a range extending from the San Juan Islands in Washington to the Channel Islands of California. It favours exposed locations battered by surf and may be found at low tide under boulders and hiding among seaweed on the lower shore. Its tube feet are very adhesive and it clings securely to rocks.
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