A small phylum of coelomate (see coelom), marine, worm-like animals in which mature individuals are unsegmented. Echiurans were formerly included in the Annelida, to which they are closely related. The body consists of a sausage-shaped, cylindrical trunk and an anterior, muscular proboscis that cannot be retracted. The nervous system is similar to that of Annelida, but there are no special sense organs. Males and females occur. They are exclusively marine, and most are burrowers and detritus feeders.
Subjects: Ecology and Conservation.