Pacific Blood Star

They can usually be identified by their bright orange-red color, but there can also be many variations from tan to almost purple. The disk can be a mottled gray color. There can also be a saddle-like marking of lilac blotches between the rays, but the rays are not mottled. They commonly have 5 rays (occasionally 4–6). The rays are smooth and appear smooth due to the lack of pedicellariae and spines. The species is relatively small; the diameter is usually over 8 cm and rarely gets larger than 12 cm. As with all seastars the blood star has a madreporite which can be seen in the image below.

Its habitat is the intertidal zone under rocks and protected places from the low-tide line to about 400 m deep. They often have a commensal scaleworm, Arctonoe vittata.

Sexes are dioecious and females are not known to brood young. This statement is in conflict with other sources that state that smaller females brood their young and larger females discharge eggs directly in the water and do not brood them. This is one reason that is leading biologists to believe this is a species complex. Embryonic stages do not adhere to one another but float freely. Post-hatching larvae are ciliated and swim. Spawned eggs have been measured at 1342 μm diameter.