Brittle stars · Ophiurida · Ophiotrichidae

Common Brittlestar

Ophiothrix fragilis

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

The common brittle star, with a small disc and five very long arms bristling with brittle glassy spines. It forms spectacular aggregations on bottoms with current, where it raises its arms to filter particles from the water.

Size

5 cm – 20 cm

Diet

Carnivore

Feeds mainly on other animals.

Activity

Nocturnal

Active mainly at night.

Social structure

Colony

Lives in large concentrations, often for breeding reasons.

Sighting difficulty

Unknown

OceanCarnivore Nocturnal Colonial Ocean Echinoderm

31countries 47parks 83dive sites

Fun facts

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 the 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.