Barnacles are encrusters, attaching themselves permanently to a hard substrate including rocky shorelines. They are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. As suspension feeders they dwell continually in their shell – which is usually constructed of six plates, reaching into the water column with modified legs. These feathery appendages beat rhythmically to draw plankton and detritus into the shell for consumption.
There are around 1,220 known barnacle species around the globe.