a family of polychaetous worms. Of the more than 20 species, four are encountered in the USSR. The worms reach 30 cm in length and are dark brown or greenish gray. The head is greatly reduced, and the pharynx is eversible. The middle portion of the body has bristles, or chaetae, and branched bundles of red gills. The worms live along coasts, mainly in the area exposed to the ebb tide. The animals dig U-shaped burrows. The worms leave conical piles of excrement on the ground near the burrows, thus making identification of their colonies easy.