Mediaster aequalis Stimpson, 1857
Common name(s): Vermilion star, Red sea star
|Mediaster aequalis from 100 m depth, San Juan Channel|
|(Photo by: Dave Cowles, July 2000)|
How to Distinguish from Similar Species: Pteraster tesselatus, Dermasterias imbricata, and Asterina miniata have similar shapes but do not have the large marginal plates. The aboral surface of Asterina miniata has ossicles but they are crescent-shaped. Pteraster tesselatus and Dermasterias imbricata have a smooth aboral surface.
Geographical Range: Chignik Bay, Alaska to Baja California
Depth Range: Low intertidal to 503 meters. In our area almost exclusively subtidal (deeper than 15 m). May be seen in fairly shallow, protected waters.
Habitat: Varies. Especially on rocky areas.
Biology/Natural History: An omnivorous predator. Prey include sponges, bryozoans, sea pens,tunicates such as Aplidium californicum and Corella spp., algae, and detritus. Predators include the seastar Solaster dawsoni. Moves fairly fast for a seastar, up to 40 cm/minute. May have an internal parasitic barnacle Dendrogaster sp. In British Columbia spawns from March to May. Juveniles often congregate subtidally among tubes of the tubedwelling polychaete Phyllochaetopterus prolifica.
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Gotshall and Laurent, 1979
O'Clair and O'Clair, 1998
Larry R. and Benjamin G. Miner, 2006. Estimation and interpretation
of egg provisioning in marine invertebrates. Integrative and Comparative
Biology 46:3 pp 224-232
A view of the underside. Photo by Dave Cowles, July 2000