The bat sea star is a sea star recognizable by its short, triangular arms connected by a membrane, giving it a silhouette reminiscent of a bat's wings.

The bat sea star generally has five arms, but their number can vary from four to nine. Its coloration is particularly variable: it can be red, orange, yellow, brown, green, or purple, with either a uniform color or a more mottled appearance.

As an adult, the bat sea star generally measures several inches in diameter and can reach up to 8 inches.

The bat sea star is found in the waters of the northeastern Pacific Ocean, along the western coast of North America, from Alaska to the Gulf of California, particularly along the coasts of British Columbia, Washington State, Oregon, and California.

The bat sea star is a common sea star species in the coastal waters of California and the Canadian province of British Columbia.

The bat sea star lives on coastal seafloors, from the intertidal zone down to several hundred feet deep. It inhabits a variety of seafloor types, including rocky areas, gravel and sandy bottoms, as well as areas where shell fragments accumulate.

It is mainly associated with rocky coastlines and kelp forests, but prefers relatively sheltered areas away from places exposed to particularly strong wave action.

The bat sea star is a scavenger and opportunistic predator. It feeds on a wide variety of organisms and organic matter found on the seafloor, including both living and dead animals and plants.

It therefore plays an important role in cleaning the seafloor by consuming, among other things, animal remains and dead organisms.

The bat sea star reproduces sexually, with separate male and female individuals. Males release their sperm and females their eggs into seawater, where external fertilization takes place. The eggs then develop into planktonic larvae that spend some time in the water column before undergoing metamorphosis and becoming young sea stars.