Brittlestars

Over hundreds of millions of years, the seas and oceans of the world have been home to a remarkable array of animals, from ammonites, fishes and belemnites to ichthyosaurs, sharks and plesiosaurs. But the seafloor was alive with movement too, particularly during parts of the Early Jurassic Period – jostling for space among crinoids and sea shells were delicate brittlestars.

Easily confused for starfish, brittlestars have five long arms and a rounded, disc-shaped body. One of nature’s great survivors, brittlestars have remained almost unchanged for hundreds of millions of years and can be found all over the world today, including in rock pools along the Jurassic Coast. We can learn a lot about the lives of fossil brittlestars by comparing them with modern species.

Brittlestars belong to a group of invertebrates known as echinoderms, which means they are closely related to starfish and echinoids. They use their arms to filter tiny plankton from the seawater or to crawl along the seafloor. Some species feed on dead animals that fall to the bottom of the sea.

The name ‘brittlestar’ is a hint at their primary defence strategy. These resilient creatures can  shed their arms when they feel threatened by a predator or, worse still, are caught in snapping jaws! We have evidence of this in fossil brittlestars from the Jurassic Coast, with a particularly neat example currently on display in Bridport Museum.