Spiny starfish

If you go down to the beach this weekend you might be lucky enough to find a mega marine invertebrate. The Spiny starfish can be found in rock pools at low water but can occur at depths of 200 metres. Spiny starfish are a type of echinoderm, an ancient group of sea-dwelling invertebrates that also include sea urchins and sea cucumbers.

Fast Facts

Latin name: Marthasterias glacialis

Notable feature: Three rows of spines on each arm

Where in the UK: South West England, Wales, N Ireland and west coast of Scotland

A spiky monster

Most Spiny starfish grow to a size slightly bigger than your spread hand – around 20-30cm. However, much larger individuals up to 75cm across have been found and these represent our largest starfish. They are particularly knobbly-looking with three rows of spines on each arm.

In glorious technicolour

Spiny starfish come in a range of gorgeous colours: they can be greyish green, bluish, light brown, pink, and they often also have purple tips to their arms!  They have three rows of spines on each arm, and these can sometimes be coloured purple too.

Not a fussy eater

Spiny starfish are voracious predators of other sea animals such as molluscs, crustaceans, fish and other echinoderms. They are not bothered whether these are dead or alive.

Not quite blind

Spiny starfish have light sensitive organs called ocella at the tips of their arms. These enable them to detect movement, which is why starfish often roll up the tips of their arms.

Where do they live?

Spiny starfish can be found on the coast of South-west England, West Wales, Northern Ireland and the west coast of Scotland.

For more information about Spiny starfish and other marine life visit MarLIN.