Common Brittlestar

Echinoderm

Identification & Biology

• IdentificationA small, delicate brittle star with a round central disc and five thin, spiny arms that break easily when handled (hence the common name). Colour is highly variable, ranging from grey, brown, and olive to red, orange, and banded patterns.
• SizeDisc diameter up to 2 cm. Arm span up to 12 cm.
• Social HabitHighly gregarious. Found in dense aggregations of hundreds or thousands of individuals, often carpeting the surfaces of sponges, rocks, and other organisms. Arms extend into the current to trap food.
• HabitatRocky reefs, sponges, and any hard surface with good water flow. Often found covering the surfaces of large sponges.
• Depth0 to 350 m. Common from the shallows to moderate depths.
• Feeds OnSuspended organic particles and plankton trapped by mucus on the arm spines. A suspension feeder.
• DistributionEastern Atlantic from Norway to West Africa, and throughout the Mediterranean Sea. Common in Maltese waters.
• DescriptionOphiothrix fragilis can occur in spectacular densities, sometimes carpeting entire sponge surfaces with a writhing mass of spiny arms. Each arm is held up into the water current, trapping tiny food particles on sticky mucus between the spines. The arms are extremely fragile and break off readily, but they regenerate quickly. The colour variation between individuals is remarkable.