The ochre sea star is a large sea star recognizable by its robust body, generally formed by five thick arms that gradually widen from the central disc. Its coloration is highly variable and may be ochre, orange, reddish, brownish or purplish, sometimes with several shades on the same individual.

Its upper surface is covered with small calcareous spines that give it a rough texture, while its underside bears numerous tube feet, or podia, which allow it to move and, above all, to grip rocks firmly and manipulate its prey.

As in other sea stars, its mouth is located at the center of the underside, and its body has a remarkable ability to regenerate.

The ochre sea star inhabits the temperate and cold waters of the northeastern Pacific ocean, along the western coast of North America, from Alaska, including the coast of British Columbia, to Baja California in Mexico. The ochre sea star is common along the coasts of California, British Columbia, Washington State, Oregon and the Pacific coast of Mexico.

The ochre sea star lives mainly on rocky shores exposed to waves, particularly in the intertidal zone where sea level rises and falls with the tides. It can temporarily remain out of the water when the tide recedes and withstand harsh conditions such as drying, temperature fluctuations and exposure to sunlight.

It is also found below the surface, down to depths of several dozen meters. At low tide, it may take shelter in damp cracks or crevices before resuming its activity as the tide comes back in.

The ochre sea star feeds mainly on mollusks. Mussels are an important part of its diet, but this sea star also consumes limpets, chitons, barnacles and other marine invertebrates.

Thanks to its powerful tube feet, it can exert enough force to gradually pull apart the valves of a mussel. When prey is too large to be swallowed whole, it can evert its stomach, pushing it out through its mouth, to begin digesting the prey directly outside its body before absorbing the liquefied tissues. This feeding strategy allows it to exploit prey that are much larger than the opening of its mouth.

Reproduction in the ochre sea star is primarily sexual, and individuals generally have separate sexes. The gonads are located in the arms and gradually develop before the breeding season. Gonad maturation follows a seasonal cycle, with substantial growth during winter and a peak reached in late spring, when adults release their gametes into the water.

Fertilization is external and produces larvae that initially live in the water column. During their development, they pass through a larval stage before settling on the substrate and gradually metamorphosing into young five-armed sea stars.