Rare purple sea star

Sunday, July 19, 2015 hamada cabo 0 Comments

 This sea star has five stout rays that range in length from 10 to 25 centimeters (4 to 10 in). The rays are arranged around an ill-defined central disk. While most individuals are purple, they can be orange, orange-ochre, yellow, reddish, or brown. The aboral surface contains many small spines (ossicles) that are arranged in a netlike or pentagonal pattern on the central disk. The ossicles are no higher than 2 mm. In Pisaster the tube feet have suckers on their distal ends which allow them to attach to the rocky substrate and live in heavily wave-swept areas.



Many sea stars live to a minimal age of four years. The Pisaster ochraceus could live as long as twenty years

This species of seastar is often considered a keystone species in many intertidal regions. Pisaster ochraceus is a predator of the California mussel, Mytilus californianus and reduces its abundance. This allows for other macroinvertebrates to persist. In an experimental removal of Pisaster ochraceus, it was shown that Mytilus californianus becomes almost completely dominant of the intertidal community. When Pisaster ochraceus is present there is a diverse intertidal community