There are only two species in this starfish family, the Short-Spined Crown-of-Thorns Starfish (Acanthaster brevispinus) and the Common Crown-of-Thorns Starfish (Acanthaster planci).
Both species are found in the Indo-Pacific region, but we only see the Common Crown-of-Thorns Starfish at the dive sites around Koh Lanta.
These starfish are disc-shaped, multi-armed starfish, starting life with the typical 5 arms, but growing many more as it matures. They are the largest starfish in the world
Members of this family are densely covered in sharp, poisonous spines, have very flexible arms and large stomachs.
The colour is usually a varying shade of blue, purple, red, brown or grey, with variably coloured spines, sometimes with yellow tips or orange.