The Black Sea Urchin is a species in the class of Sea Urchins and thus belongs to the phylum of the Echinodermata. Arbacia lixula was first described in 1758 by Linnaeus.
Description
The body of the Black Sea Urchin has the shape of a hemisphere. Its strong spines all have about the same length. There is therefore no shorter, secondary spine, which makes it easy to distinguish the Black Sea Urchin from other, similar species.
Its colour is black. However, it may also have partial grey to white spines.
The anus sits centrally on the upper side and is surrounded by four plates.
Arbacia lixula reaches a maximum diameter of 10cm and the spines are up to 3cm long.
Habitat and Distribution
The Black Sea Urchin lives on rocky ground. It can be found from very shallow water down to depths down to 30m. Arbacia lixula is also to be found in rock pools.
When scuba diving in the Canaries you can observe it very often. Especially in the case of night dives, one can see how many individuals are walking around the reef.
Its distribution area spreads over the Macaronesian Islands, which are the Azores, Madeira, the Canary Islands and Cape Verde. Arbacia lixula is also found in the Mediterranean Sea, rarely on the West African and Brazilian coast.
Biology
The Black Sea Urchin feeds preferably on algae.
At a low density of individuals, it usually hides during the day in holes and columns. In places with many single animals, as it is often the case in the Mediterranean Sea, for example, they can be seen outside during the day too.
References