The Hippasteria spinosa is an uncommon, 5 armed, aboral surfaced sea star. Its most marginal plates have 2 spines and it has some conspicuous bivalved pedicellariae.

Its colour is orange to vermillion, which intensifies at the short, stalky arms (R/r=1.7 to 2.6) and becomes whiter near the mouth. Usually in the subtidal region at depths of 100 to 500 metres, it can sometimes be found on the beach. It is characterised by having all its plates covered with granules, giving it a spiny, STELLATE look.The mouth has 4 or 5 marginal spines and a slightly wider than high mouth (elipsis shape).

Habitat and region

Can be found from Kodiak Island to Southern of California and the Sea of Okhotsk and is more common around the west coast of Vancouver Island and other exposed coastal parts. It prefers muddy, shallow environments and can also be found in shell and rock.

References:
Taxonomy: Marine Invertebrates of the Pacific Northwest; Kozloff, Eugene, University of Washington Press, 1996 Edition, USA