Autozooids are responsible for the feeding, gonozooids specialize in reproduction, the avicularium is the individual that acts as the defense for the colony, the vibraculum keeps the colony clear from sediment, and the kenozooid is a structural individual for building of the colony. Andrea Martin , Sophomore at The College of Wooster. Andrea is from Draper, Virginia. These animals are evolutionarily related to brachiopods, because both are lophophorates. A lophophore is a ring of feathery tentacles around the mouth that collect food and take it to the mouth for feeding.
Bryozoans also have a U-shaped digestive tract.
They do not have a heart or vascular system though. Because of the bryozoans' small size, they respire and excrete waste by diffusion. Bryozoans show several evolutionary trends. One is the increased calcification of their skeletons. This move helped the bryozoans expose less of their soft tissue so that they could more easily escape predation.