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. Early bryozoans built tall branching colonies. But later they were flat and spread out. This is a better colony for the bryozoans because they can spend more time reproducing and carrying out other life processes and less energy on building elaborate structures.