Priapulans: Priapulida

With the introvert fully extended, priapulans grasp prey with their teeth and rapidly roll it inward. Priapulans depend on their fluid skeleton for movement. They use their extended introvert and the muscles of the front part of their trunk to anchor themselves in the sand. Once anchored, priapulans can pull themselves through the sand by contracting their body wall muscles.

Priapulans have separate sexes. They release their eggs and sperm into the water, where fertilization (FUR-teh-lih-zay-shun), or the uniting of egg and sperm to start development, takes place and larvae develop. Larvae (LAR-vee) are animals in an early stage that change form before becoming adults.