Calvert, Eastover, Yorktown, and Tabb
Barnacles are sessile crustaceans, which means they do not
move around. Larvae are free-swimming for a short time, and then they attach
their heads to a hard surface (shell, log, or rock). They then build a protective
shell around themselves out of calcite, a mineral composed of calcium carbonate.
Barnacles feed when covered by water by extending feathery legs to trap food
particles, and can close off their shell entirely when water levels drop during
low tide. They retain sufficent moisture inside the shell to last until water
covers them again at high tide. This adaptation allows barnacles to live successfully
in intertidal areas.