A rare visitor to our shores generated much interest after an Echo reader brought a cluster of what looked like a type of mussel attached by “stems” to a central white waxy substance, found on Fish Hoek beach on Thursday November 3. The reader said he hadbeen walking on the beaches for 50 years and never seen one.
Photos were sent to researchers at Marine and Coastal management where Glencairn resident and researcher Rob Tarr identified it as buoy barnacles (Dosima fascicularis).
“What is interesting about this species is that it creates its own float, unlike other goose barnacles that attach to whatever they can find floating on the surface,” he said. More than one barnacle is attached to the float.
“I have never seen one on a beach anywhere,” he said, adding that he had read about strandings of the barnacle at Cape Point.
Inside most of the barnacles was what looked like a little shrimp – these are the filter feeding appendages for eating plankton.
According to the Marine Life Information Network, an initiative of the Marine Biological Association of the UK, the buoy barnacle was first noted in 1786 in St. George’s Channel, between Wales and Ireland and was described in a monograph by Charles Darwin.
“The young forms settle on small floating particles in the water, and as they grow they produce a spongy secretion from modified cement glands, comparable in texture to polystyrene, which keeps them near the surface of the water and is increased in volume as the barnacle grows,” says the website. “Other individual barnacles attach to the float and in this way a large colony is constructed. Sometimes the buoy barnacle attaches to larger objects including feathers lost from sea birds … and even old tar balls that have lost the toxicity of the original crude oil.”
The barnacle colony floats in the ocean, moving with the currents, with the barnacles hanging down in the water. They prefer the temperate seas of the Atlantic and Pacific Oceans, and has been found at latitudes from 71° North off Siberia to 57° South near Cape Horn.
The shells can be pale yellowish to purplish-brown in colour and each can be between one and three centimetres long, but is most commonly two centimetres long. The shells are thin and papery and the empty shells resembled cellophane.
Article written and supplied by Michelle Saffer of the False Bay Echo
I managed to collect some live Buoy Barnacles this morning and sent them to the Two Oceans Aquarium who is making a display of them. They have been washing up all along the Western Cape coastline with sightings from Agulhas and Paternoster. They are very rare and the marine experts at UCT have never seen a live one. They belong to the same family as the goose barnacles that often wash up attached to pieces of wood that have been in the sea for a long time. We are incredibly lucky to be seeing them. See my photo of a live Bouy Barnacle community.