Harbors and rocky shorelines are often littered with barnacle tests (or shells), yet relatively few people have actually seen the animals that live inside of  these dome-shaped homes.  Here’s some high-speed footage that I took of a barnacle feeding in a wave.

Barnacles are crustaceans, so they are related to animals such as crabs and lobsters.  They are in fact somewhat crab-like in appearance once you pull them out of their tests.  Unlike crabs and lobsters, barnacles have adapted to a sessile life by hanging upside down inside of their tests and extending their feeding legs (cirr) into the water to capture food particles.