''Pisaster'' (from Greek ', "pea", and ', "star"
[Cleveland P. Hickman et al., ''Integrated Principles of Zoology'' (St. Louis: Times Mirror / Mosby College Pub., 1984),]
p. 469
) is a genus of Pacific
sea stars
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish a ...
that includes three species, ''P. brevispinus'', ''P. giganteus'', and ''P. ochraceus''. Their range extends along the Pacific coast from
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...
to southern
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
in the
intertidal
The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...
zone. The largest individuals of ''Pisaster'' can reach diameters of up to across; they all develop five arms, but some may be lost from injury or disease, and occasionally the re-growth of an injured arm will result in an individual with more than five arms.
Sea stars in the genus ''Pisaster'' are all predators; the
ochre sea star is the best-characterized of these, and is considered a "keystone" predator that controls the relative abundance of many other species in the ecosystem.
Species
References
Asteriidae
{{Asteroidea-stub