There are a total of 10 species in the genus Arbacia with Arbacia Lixula being the commonest in the Mediterranean. This is the regular urchin, often up to 50mm in diameter with a low flat profile recognized by its thick black spines which are often around 30mm long. Usually found on rocky substrate from from water level to a depth of 5m although they have been found as deep as 50m. Black being the commonest colour for their shell but also seen are different shades of green, olive, brown, purple and red. Their name “urchin” originates from the hedgehog that they resemble!
Spreading across the coastal Mediterranean it is usually found on rocky substrate from from water level to a depth of 5m although they have been found as deep as 50m favoring vertical inclines of rock. Less common in the northwest Mediterranean.
They are slow moving feeding on mostly algae. Mainly feeding on encrusting coral lines.
Similar to other echinoids they are gonochoristic. They become ripe during early spring triggered by an external change in temperature or disturbance.