Angled-jaw worms

Although the angled-jaw worms (Family Goniadidae) superficially resemble their close relatives, the bloodworms (Glyceridae), significant differences exist. Species in both families have a proboscis that is eversible (can be turned inside out), but the jaw apparatus for each is distinctive. Other important anatomical details, such as the shape of the appendages (parapodia) and their associated bristles (chaetae), must be examined in detail to distinguish the species. Little is known about the biology of these worms.