Ivory Acorn barnacles

Description:

6 vertical plates .Approximately 1cm in ht operculum diamond shaped. Found submerged on the post under a bridge. Acorn barnacles, related to shrimp, hide their identity in snail-like shells. But they begin life as free swimming larvae. When the time comes to settle, the larvae "glue" their heads to hard surfaces, such as pilings, wharfs, ships, rocks or other hard-shelled animals. Once attached, they change into juvenile barnacles, minatures of the adults. Then each builds its own fortress—a cone-shaped limestone shell with a trap door in the ceiling. When water covers a barnacle, the trap door opens, and the barnacle's feathery legs emerge to sweep the water for plankton and detritus. When the tide is out, barnacles close their trap doors to conserve moisture. Barnacles spend the rest of their lives in this position—head down and feet up.

Habitat:

colorado lagoon ,long beach california.