Giant Acorn Barnacle

Giant Acorn Barnacle (Balanus nubilus)

This HUGE barnacle is one of 23 kinds of barnacles found in the Salish Sea, and is known as largest barnacle species in North America and possibly the world, growing to approximately half a foot across. They are commonly found in reef-like formations from Alaska down to California, growing in clusters on pier pilings, rocks, hard-shelled animals, and even on top of each other, in the intertidal zone to depths of 90 metres. They prefer strong tides and waves.


Volcano-looking Cluster of Giant Acorn Barnacles

This invertabrate looks a lot like a volcano with a large, jagged opening (aperture), ridged sides, and a worn looking exterior containing beak-shaped, moveable plates which flash bright yellow to purple muscle tissue during feeding. When the tide moves in and water washes over the barnacle, these plates open up like a trap door so that it can extend its feathery feet (cirri) to sweep the water for drifting plankton and detritus. Once the tide recedes, the plates close to capture the food and retain moisture, a filter feeding process that continues with the tide cycle.

This barnacle contains cement glands that excrete a glue-like substance so that it can attach its head to a rock (and remain there for the rest of its life). This glue is apparently so powerful, that it cannot be dissolved by most acids and alkalis, and is being studied for potential adhesive uses. In fact, after the barnacle has died, its empty casing remains fixed in place, making a great move-in residence for other creatures such as the Pacific red octupus, pygmy rock crab, and small fish. Who eats the Giant Acorn Barnacle? Predators include purple sea stars, sea otters, and crabs.

http://www.centralcoastbiodiversity.org/giant-acorn-barnacle-bull-balanus-nubilus.html

http://www.neaq.org/blog/giant-acorn-barnacle/



https://www.vanaqua.org/marine-biodiversity/worms/tubeworms/tubeworms-in-howe-sound/