Volcano Barnacle

Crustacean

Identification & Biology

• IdentificationA large, cone-shaped barnacle with a rough, ridged outer shell that can resemble a tiny volcanic crater. White to pale grey. Much larger than the stellate barnacle, with a wider opening at the top.
• SizeShell diameter up to 3 cm and height up to 2.5 cm. One of the largest barnacle species in the Mediterranean.
• Social HabitColonial. Forms dense clusters on hard substrates in the intertidal and shallow subtidal zones. Filter feeds using feathery leg-like appendages extended through the shell opening.
• HabitatIntertidal and shallow subtidal on rocky shores, harbour walls, pier pilings, and any hard surface. Tolerates a wide range of conditions.
• DepthIntertidal to 5 m. Occupies a slightly lower position on the shore than the stellate barnacle.
• Feeds OnPlankton and suspended organic particles filtered from the water.
• DistributionEastern Atlantic from the British Isles to West Africa, and throughout the Mediterranean Sea. Common on all Maltese rocky shores and harbour structures.
• DescriptionBalanus perforatus is the large, cone-shaped barnacle commonly seen on rocks, sea walls, and harbour structures around Malta. Like all barnacles, it is a crustacean that cements itself to hard surfaces as a juvenile and spends its adult life upside down, kicking food into its mouth with its feathery legs. The empty shells of dead barnacles create rough, textured surfaces that provide microhabitat for many other small organisms.