Evasterias troschelii (Stimpson 1862)

How to Distinguish from Similar Species: Small individuals look somewhat like a Pisaster ochraceous or P. brevispinus, but this species has longer rays in proportion to its central disk and the rays narrow before they meet the central disk, and the aboral ossicles are not arranged in a clustering network.

Geographical Range: Pribilof Islands, Alaska to Monterey Bay, CA; Kamchatka. Uncommon south of Puget Sound. This is the most abundant large, intertidal star in the Juneau area.

This seastar has a small central disk and 5 long rays which are not bordered by obvious marginal plates. The rays usually narrow as they attach to the central disk and are widest at a point slightly out from the central disk. Exposed ossicle spines and pedicellariae make the aboral surface rough. Clusters of pedicellariae are especially visible near the ambulacral grooves, and are usually in clumps at the bases of spines. Has both crossed and straight pedicellariae. Color highly variable: gray, blue-gray, greenish, brown, orange, reddish, pale purple; frequently margins of rays are a different shade than aboral surface. Radius up to 28 cm.

Biology/Natural History: Feeds on a variety of animals--bivalves, limpets, snails, brachiopods, barnacles, and tunicates. Can evert its stomach. Several limpets exhibit escape responses from this species. May have a symbiotic scaleworm living in the ambulacral groove or on the body surface. In Alaska one can often find the young of the Alaska King Crab nestled between the rays of this seastar. Predators include gulls, Solaster dawsoni,and Pycnopodia helianthoides; and attacks by the rose star Crossaster papposus and by Alaska King Crab Paralithodes camtschaticus have been observed. Tolerant of reduced salinities down to 20 ppt.

On rocks and cobbles; sometimes on docks and pilings. More abundant intertidally in protected areas than along the open coast.

Depth Range: Low intertidal and subtidal to 70 m. Mostly subtidal in the Rosario area.