Marthasterias

As of October 2023 the accepted species are:[2] Marthasterias glacialis is a fairly large starfish with a small central disc and five slender, tapering arms.

Each arm has three longitudinal rows of conical, whitish spines, usually with purple tips, each surrounded by a wreath of pedicellariae.

The background colour is variable and may be brownish or greenish-grey, tinged with yellow or red and sometimes with purple at the tips of the arms.

[3] Like other starfish in the family Asteriidae, Marthasterias glacialis is a predator and feeds mostly on bivalve molluscs and other invertebrates.

[8] The reproductive biology of this starfish has been little studied but off the coast of Ireland, individuals gather together in very shallow water in July and August.

Detail of tip of arm showing tube feet extended