Blue sea star
Linckia laevigata
Cushion Star
Asterina gibbosa
About
The cushion star is a small, puffy-looking starfish that lives along the shores of the northeast Atlantic and Mediterranean. It hides under rocks by day and comes out at night to graze on the film that coats the rocks.
Also known as: starlet cushion star
- Depth
- up to 126 m
How to tell it apart
It looks almost identical to the smaller Asterina phylactica, but this species has a pair of tiny spines on each plate ringing its mouth, which phylactica lacks entirely.
Appearance
This starfish has a five-sided outline, with short, blunt, rounded arms that give it a puffed-up, cushion-like look. Its upper side is covered in clusters of short, blunt spines, and its colour ranges from brown to green to orange, sometimes with blotches. Animals from deeper water tend to be paler.
Habitat
It lives from rock pools on the lower shore down to about 126 m, sheltering on rocks, under boulders, and in overhangs. It is found along the coasts of the British Isles, south through the Mediterranean and out to islands in the eastern Atlantic.
Behaviour
It is mainly active at night, spending the day tucked under boulders, in overhangs, or hidden in algae within rock pools. It feeds by pushing its stomach out onto the rock and digesting the film of bacteria and tiny algae that grows there. It sometimes scavenges dead seaweed or bits of dead shellfish too. It is born male and later changes sex to become female as it grows.
Did you know?
Unlike most starfish, whose larvae drift and feed in the plankton, this species' eggs hatch straight into a larva that crawls and settles almost immediately, skipping the free-swimming stage.
Log it in Into the Blue
Describe what you saw and we name it, then keep every species you find in your Oceandex.
