Common Brittlestar

• Its beds can exceed a thousand individuals per square metre and cover kilometres of seabed, forming a living carpet that filters the water and reshapes the sediment.
• It breaks with extraordinary ease: at the slightest tug it sheds an arm, which it later regrows, and hence its name.
• Unlike sea stars, it does not move on tube feet but by snaking its arms, a fast and surprisingly agile motion.
• It forms spectacular aggregations: in the English Channel densities of more than 2,000 individuals per square metre have been measured, carpeting kilometres of seabed.
• It does not feed off the bottom: it raises its arms into the current and catches suspended particles on its spines and mucus, so those carpets work as a gigantic filter.
• It is called brittle for good reason: it sheds its arms readily at the slightest handling, and then regrows them.
• It moves by writhing its arms, far faster than a starfish, rather than walking on its tube feet.

Habitat and environment

Rocky, gravel and shell bottoms of the north-eastern Atlantic and the Mediterranean

Sources consulted: Abildgaard (1789) · Marine Life Information Network · Warner y Woodley (1975)