Barnacles are small, grayish-white crustaceans that live on rocks, pilings, boat hulls and other hard surfaces throughout the Chesapeake Bay.
Four species of barnacles can be found in the Chesapeake Bay:
Barnacles vary in size from less than half an inch to 1 inch in diameter, and have six overlapping grayish or whitish shell plates. They have a flat base and an opening at the top that has two valves that open and close like "trap doors."
Live on rocks, reefs, jetties, pilings, grasses, boat hulls and other hard surfaces.
Found throughout the Chesapeake Bay, from salty waters to nearly fresh water. The bay and white barnacles are more common in the northern half of the Bay, while the ivory and little gray barnacles are mostly found in the lower Bay
Barnacles feed while submerged underwater. The barnacle’s “trap doors” rhythmically open and close, and feathery appendages emerge to collect and sweep in tiny food particles such as plankton and detritus.
Barnacle larvae are an important food source for young fish in the spring. Flatworms are major predators of adult barnacles. Sponges, bryozoans and similar animals can grow on top of barnacles and smother them.
Spawning occurs in mid- to late spring. Each barnacle has both male and female organs, but eggs must be fertilized by another barnacle. A sperm tube extends from one barnacle into a neighboring barnacle to fertilize its eggs. Once the eggs hatch, the barnacle releases tiny larvae into the water. Larvae go through two stages, each lasting a few days. Second-stage larvae search for a suitable hard surface to attach, usually among adult barnacles of the same species. Larvae attach themselves to a hard surface using a cement-like substance secreted from a special gland. After attaching, larvae develop shell plates that eventually cover their body.