Spiny Starfish – Marthasterias glacialis
The Spiny Starfish is a species in the class of the Starfish and therefore belongs to the phylum of the Echinodermata. It was first described in 1758 by Carl von Linné.
Marthasterias glacialis has a green colouring with orange thorns that are surrounded by light blue dots. It got five arms and can reach a size of up to 100cm in diameter, but it usually does not exceed 30cm.
Habitat and Distribution
The Spiny Starfish lives on rocky and muddy grounds down to depths of 200m. When diving in the Canaries you can see it frequently. In addition, its distribution range extends from Iceland via Finland, Norway, Ireland, the west coast of Great Britain, the Azores to Cape Verde, the Gulf of Guinea and South Africa. It can also be seen in the Mediterranean Sea.
Marthasterias glacialis feeds on mussels, snails, echinoderms, sea squirts and crustaceans. It opens e.g. mussels with the force of its suction feet and then pushes its stomach outwards.
Only little is known about reproduction. During July and August Spiny Starfish gather in shallow water at the coast of Ireland. Males have a minimum size of 2,5cm while females are usually bigger than 9cm. Few days later sperm and eggs are released into the seawater and external fertilization takes place. A new starfish then develops threw several larval stages.
In an emergency, can unhook an arm and sacrifice it so that itself can survive.