Poli’s Stellate Barnacle – Chthamalus stellatus

Poli’s Stellate Barnacle is a species in the order of the Sessilia and thus belongs to the subphylum of the Crustacea. Chthamalus stellatus was first described in 1791 by Poli.

Poli's Stellate Barnacle - Chthamalus stellatus Crustacea Sessilia species diving canary islands canaries atlantic ocean
Poli’s Stellate Barnacle – Chthamalus stellatus


The shape of Poli’s Stellate Barnacle resembles a volcano crater. Their colour is white to beige. When Chthamalus stellatus is open, bright blue and orange colours occur as well.

It can reach a size of up to 14mm in diameter.

Habitat and Distribution

Chthamalus stellatus lives on rocky ground, marking the line of medium tide. They are underwater at high tide and outside the water at low tide.

When diving in the Canaries we can not observe them. But they are quite frequent in a walk along the coast and in tide pools.

Apart from the Canary Islands, Chthamalus stellatus has a huge distribution area. From the British Isles, it reaches the Azores, Madeira all the way to Cape Verde. In addition, you will find Poli’s Stellate Barnacle in the Mediterranean Sea, the Red Sea and the Black Sea. In general, they prefer islands and sheltered bays.


Chthamalus stellatus live sessil as adult animals, so they do not change their location. Most of them can be seen in large colonies.

They feed on plankton and detritus, with their modified legs, swirling into the interior of their shell.

Reproduction & Developement

Poli’s Stellate Barnacle is a hermaphrodite that can fertilize itselves in case it is isolated. Usually, however, the individual animals perform the male or female role in reproduction.

Chthamalus stellatus penis is much longer than its body and is used to find a female close by. The females produce between 1000 and 4000 eggs that are hatched. As a larva, it first swims freely with plankton in the current. After several moults, a metamorphosis to the cybrid larva takes place. At this stage, it can not eat any food. The cybrid larva attaches itself with the forehead to a suitable place and after yet another metamorphosis it becomes an adult Poli’s Stellate Barnacle.






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