oligochaete science definition

Any of various annelid worms of the class Oligochaeta. Oligochaetes, unlike polychaetes, have relatively few bristles (called setae) along the body, and often have a thickened, ringlike region (called a clitellum) that secretes a substance used for enclosing eggs in a cocoon. Oligochaetes include the earthworms and a few small freshwater forms. Compare polychaete.