Spiny starfish

Marthasterias glacialis


Our largest starfish, reaching an impressive diameter 70cm.  It is a predator, feeding on shellfish including cockles, mussels and barnacles. 

How to identify

It is covered in three rows of spines on each of their five arms. Their whitish grey-green colour stands out even more because of the purple tip on each arm. They can grow up to a huge 80cm across but most are smaller. Average size is 30cm across.

Where to find it

Most commonly recorded on the southwest and west coast of Britain and Ireland. Found in a variety of habitats including sheltered muddy sediments and exposed rock faces. It thrives from the subtidal zone and down to 200 meters.


When to find it

  • January
  • February
  • March
  • April
  • May
  • June
  • July
  • August
  • September
  • October
  • November
  • December

How can people help

Our seas and coastline are in need of protection if we are to keep our marine wildlife healthy. The Wildlife Trusts are working with fishermen, researchers, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. This work has recently had a massive boost with the passing of the Marine Bill, promising sustainable development of the UK's marine environment. Do your bit for our Living Seas by supporting your local Wildlife Trust. You can also help by reporting your sightings to Devon Wildlife Trust or to the Devon Biodiversity Records Centre.

Species information

Common name
Spiny starfish
Latin name
Marthasterias glacialis
Urchins and starfish
Diameter: 30cm