Porania pulvillus is a sea star of a diameter of 12 cm. The central disc
is broad and domed, the five short arms are stout and tappering. The dorsal side is red, orange or
yellow with irregular white lines. It is covered in tiny papulae, white to yellow or even translucent,
in the middle of which one can see the madreporite. Its surface is smooth and somewhat greasy to the
touch. The ventral side is paler. Two rows of tube feet with sucking disc radiate from the mouth toward
the tip of each arms. Plates on the edge of the red cushion star bear 3 to 5 spines forming a sort of
fringe around the starfish. It is mainly detrivorous but it seems that it may also feed on the
cnidarian Alcyonium digitatum on which it may be sometimes observed.
Porania pulvillus is found on rocks, kelp holdfasts in sheltered or moderatly exposed areas generally from 10 to 300 m deep, but sometimes as deep as 1000 meters, in the Atlantic Ocean from South Ireland up to Norway, in the english Channel and the North Sea.
(source : European Register of Marine Species)
Madreporite : Perforated plate on the upper surface of the starfish through which water comes in
the water vascular system, that enables the tube feet to move.
Papillae : Kind of tiny bags more or developped on the surface of the starfish and used in breathing.
Tube foot : Tube-shaped element ending by a sucker-disc used to attach to subtratum or to bring food particles into the mouth.
Top Photo :
© Mat Vestjens. Published with author's kind permission :
Porania pulvillus, Lysefjord, Rogaland, South-West Norway. Depth 15 meters.
Text : Anne Bay-Nouailhat © 2008-2017.
Translation : Anne Bay-Nouailhat © 2008-2017.