SEA STARS OF THE PACIFIC NORTHWEST THORNY STAR Poraniopsis inflata

Class Asteroidea

Order Valvatida

Family Poraniidae

THORNY STAR

Poraniopsis inflata (Fisher, 1906)

Identification:

5 fat arms. Aboral surface mesh-like with many white, sharp spines. Cream to bright orange. To 20 cm (8 in) across.

Range:

Gulf of Alaska to southern California; also in Japan and Russian waters; 8 to 366 m (26 to 1,207 ft).

The sharp spines and puffy body are very distinctive. Note the madreporite between the two closest arms.

A close-up view of the surface shows the stout spines and the dense clusters of papulae (gills). The gills give the star a fuzzy appearance.

Note the OVAL CUP and ORANGE CUP CORALS near this THORNY STAR. These solitary cup corals are likely prey for this star.

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Notes:

Uncommon. I’ve seen only a few of these puffy, very spiny stars, all on the west coast of Vancouver Island. The wicked spines are seriously sharp: be careful when handling one if you wear dry gloves. One area where there have been a few sightings is the seaward end of Alberni Inlet in Barkley Sound on the west coast of Vancouver Island. Here at dive sites such as Mutine Point and Tyler Rock one might encounter a THORNY STAR.

I've also seen them in Quatsino Sound at Brockton Island, on the west coast of Vancouver Island. Not much is known about its feeding habits, however I have found them amongst populations of OVAL CUP CORALS Paracyathus stearnsi and ORANGE CUP CORALS Balanophyllia elegans.

Also reported from Tasu Sound on the west coast of Haida Gwaii (Queen Charlotte Islands) by Phil Lambert where they were found among OVAL CUP CORALS. Captive animals reportedly prefer sponges, which they envelop with their large, eversible cardiac stomach.