Barnacles attach head first to rocks, shells, pilings, boats, buoys, etc. When the tide is in, their feathery legs, called cirri, sweep through the water for phytoplankton. Although they look like mollusks, barnacles are actually crustaceans, like shrimp and crab.
Barnacles spend their infancy as free-swimmers and molt several times during their lives. Occasionally you'll see a free-floating barnacle drifting through the water.
Below: adult barnacles. These guys are sharp, and the number one reason why you should always wear foot protection when swimming in Hood Canal.
There are lots of barnacles in our retail live tank, and customers of all ages get excited whenever they see the barnacles feeding. However, our nascent photographic skills have resulted only in smudgy underwater photos of rock-like creatures, and so, to communicate the wonders of a barnacle feeding, we have to rely on YouTube.
Barnacle reproduction is way more interesting than oyster or clam reproduction: barnacles, which are hermaphrodites, fertilize one another with a penis that can stretch 20 times their body length.
Below: barnacle sex.