Balanus nubilus

"Giant barnacle" redirects here. For the species from Argentina, Chile and Peru, see Austromegabalanus psittacus.

Balanus nubilus, commonly called the giant acorn barnacle, is the world's largest barnacle, reaching a diameter of 15 cm (6 in) and a height of up to 30 cm (12 in),^[3] and containing the largest known muscle fibres.^[4][5]

Balanus nubilus
Giant acorn barnacles with cirri extended for feeding
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Thecostraca
Subclass:	Cirripedia
Order:	Balanomorpha
Family:	Balanidae
Genus:	Balanus
Species:	B. nubilus
Binomial name
Balanus nubilus Darwin, 1854[1][2]

Classification

Balanus nubilus was named by Charles Darwin, who described its appearance and noted its habitat. He wrote that the barnacles were found on rotting wood and were associated with Balanus glandula. Darwin said the barnacles were "very distinct" but thought that the species allied with Balanus balanus more closely "than to any other species", and also allied with B. cariosus.^[1]

Ecology

Balanus nubilus is a northeast Pacific species that ranges from southern Alaska to Baja California.^[6] It is frequently found growing on rocks, pier pilings and hard-shelled animals at depths of up to 90 m (300 ft).^[4] Like other acorn barnacles, B. nubilus is a filter feeder; it, in turn, is sometimes eaten by sea otters,^[7] sea stars, crabs^[8] and the Native Americans of the Pacific Northwest.^[9] Abandoned shells of B. nubilus are used by the crab Glebocarcinus oregonensis for shelter.^[10]