#2421 - Chamaesipho sp.
Barnacles belong to the subclass Cirripedia, a name derived from the Latin for "curly foot" alluding to the animal's curved legs. The common name barnacle derives from Old French bernaque and medieval Latin bernacae or berneka, but the word actually referred to the barnacle goose Branta leucopsis, because of a belief that goose barncles were the infant stage of the bird. Not, in fact, as deranged as it sounds, given nobody in Europe knew where barnacle geese came from every year, and driftwood covered in goose barnacles did vaguely resemble trees covered in weird long-necked fruit.
By the 1580s the word was being applied to the crustaceans instead. Not that anybody suspected they were actually crustaceans until 1830, when John Vaughan Thompson studied the metamorphosis of their larvae. Between 1846 and 1954 Charles Darwin worked on the group so intensely "that his son assumed all fathers behaved the same way: when visiting a friend he asked, 'Where does your father do his barnacles?'" Upon the conclusion of his research, Darwin declared "I hate a barnacle as no man ever did before."
Barnacles are usually filter-feeding marine crustaceans, although some are highly modified parasites - one genus embeds itself in the spine of deep-sea sharks. Acorn-type barnacles like Chamaesipho glue themselves to the substrate by their foreheads, grow calcereous plates for protection, and spend the rest of their lives kicking plankton into their mouth. They're also famous for their incredibly long penises, that they need to reach their neighbours.
Gooose barnacles and some larger species of acorn barnacle are collected for food. Species growing on the hulls of ships are serious fouling organisms.
Chamaesipho is a genus of Chthamalid barnacles found in Australian and Aotearoan temperate waters, with three extant species and one extinct. They are usually intertidal in preference, and tend to form crowded columnar colonies. Other genera in the Chthamalidae are found in all oceans except the Arctic Ocean, in temperate and tropical zone.
Puritutu Rock, New Plymouth, New Zealand