Learn About Acorn Barnacles

There are 5 common species of acorn barnacles found intertidally on west-coast shores, and several other species live subtidally.  Included is the largest species in the world, Balanus nubilis. 

NOTE  the origin of the word “barnacle” is obscure, but may derive from O.F. bernaque meaning “goose”.  It seems that the English name was first applied to a bird called the barnacle goose, because it was believed that these birds grew from certain “Muskles” (a generic term for shore-dwelling shellfish and, specifically, what we now know as goose barnacles) growing on trees cast up on the shore by ocean waves.  This story is presented elsewhere in THE ODYSSEY: GOOSE-BARNACLE LEGEND.  Barnacles were only recognised to be crustaceans in the 1800’s when researchers noticed the distinct arthropodan features of their larvae.  Barnacles, along with shrimps, isopods, crabs, and amphipods (in order of appearance in the ODYSSEY) are classified in the Subphylum Crustacea in the Phylum Arthropoda

ANIMATION of snail meeting BARNACLE
© 2010 Thomas Carefoot

map showing snail's route to the top of the shore from A SNAIL'S ODYSSEY

To learn about west-coast ACORN BARNACLES: select a topic from the Crustacea > Acorn barnacles menu at the top of the page

OR: play the ANIMATION of the snail meeting the BARNACLE

OR, if you want to see other animations: follow the snail on its ODYSSEY by CLICKING on any X-marked invertebrate on the map

Phylum Arthpropods (lit. “soft” or “shellfish” L.)

Subphylum Crustacea (lit. “crust or rind” L.), referring to the hard calcified exoskeleton

Class Maxillopoda (lit. “jaw feet” G.), including barnacles

Infraclass Cirripedia (lit. “curl of hair feet” L.), referring to the frilly appearance of the feeding appendages of a barnacle, derived from locomotory appendages of the larva; includes acorn barnacles (e.g., Balanus glandula, B. nubilis, Semibalanus cariosus, Chthamalus spp.), goose barnacles (e.g., Pollicipes polymerus), and some parasitic species, e.g. Coronula diadema that live on whales

NOTE  this abundant and ecologically important west-coast species has been introduced into 3 separate port areas in north-eastern Honshu, Japan during the last 20-40yr.  It has become a dominant littoral-zone species in these areas.  It apparently was also introduced into the La Plata estuary of Argentina at about the same time.  Based on records of harbour customs offices along the north-east coast of Japan, it seems likely that the original colonisation was from larvae of adults present on hulls or in ballast water of ships arriving from the Pacific coast of North America.  Kado 2003 Mar Ecol Progr Ser 249: 199.