Bryozoans are yet another group of community minded invertebrates. The colony is made up of a network of individuals that live in box-like structures made of chitin (kite-in), a tough protein also found in insect exoskeletons, or calcium carbonate. They will form mats on any hard substrate, including kelp blades.

Bryozoans feed on small microorganisms, including diatoms and other unicellular algae. These are trapped by feeding tentacles. In turn, bryozoans are preyed on by grazing organisms such as sea urchins and fish, and are also subject to competition and overgrowth from sponges, algae, and tunicates.