Marthasterias glacialis is a starfish of 30 to 40 cm in diameter
but it may be up to 80 cm. Its surface is covered by linear papillae from which arise large conical spines
surrounded by numerous pedicellariae easily visible under magnifying glass. The colour is variable:
whitish, bluish, pink, purple, greenish-grey or brown. It has five cylindrical tapering arms with
a photosensitive ocella at their tips. For this reason, the spiny starfish often rolls up its
arm-tips to detect movements. It feeds on various animals, dead or alive, such as molluscs, shellfish,
fish or other echinoderms. It is a voracious starfish which may cause important damages in mussel and oyster
farmings. Very common on Brittany coasts, it has seen its population grow very quickly because of
its great regeneration ability: regularly caught in fishers'nets, they were torn to pieces and thrown
back to sea by fishermen firmly believing that thus the starfish would die!
It lives on rocky bottoms from surface to depths up to 180 m. It is found in the Atlantic Ocean, the English Channel, the North Sea and the Mediterranean Sea.
(source : European Register of Marine Species)
Pedicellariae : Minute jawed elements of sea urchins and starfish used to clean body surface and as defensive means.
Top photograph :
© Wilfried Bay-Nouailhat. Published with author's kind permission :
Marthasterias glacialis, Baie de Concarneau, South-Brittany, West of France. Depth 5 meters.
Text : Anne Bay-Nouailhat © 2005-2017.
Translation : Anne Bay-Nouailhat © 2007-2017.