Seastars at Axial

Two unknown species of seastars (Phylum Echinodermata, Class Asteroidea) have been photographed at Axial.

Unknown Seastar 1 (Mediaster sp.?)

Seastars (Class Asteroidea) and Brittle Stars (Class Ophiuroidea) belong to Phylum Echinodermata. Photo credit: NSF-OOI/UW/CSSF; Dive R1727; V14

This bat-star (shown to the left of a brittle star) has been observed on several occasions, living on the lava rocks on Axial’s caldera.  It has characteristics similar to members of the Genus Mediaster, which are common in the Pacific.

Unknown Sea star 2 (possibly Henricia sp.?)

An unidentified sea star (possibly Henricia sp.) near one of the vents during a dive to the International District. It remained next to the chimney, despite the heat exuded by the vent plume. Photo credit: NSF-OOI/UW/CSSF; Dive J2-1381; V21.

This species is also fairly common, seen lounging on the basaltic lavas of Axial.  Its long, spiny arms are similar to those sea stars in the Zoroaster Genus.