Sand Worms Clam Worms and Tubeworms: Polychaeta

Clam worms, sand worms, and tubeworms range in length from 0.078 inches to 9.8 feet (2 to 300 millimeters). Their bodies consist of a head, body trunk, and tail. Most species have long, segmented bodies that are tubelike and covered with bristles. Along the sides of their bodies are flaps that help them to swim, burrow, draw bits of food suspended in the water to their mouths, and grip surrounding rocks, sand, or mud. The side flaps are also used like gills to help them breathe underwater.

Clam worms, sand worms, and tubeworms vary in color, ranging from clear to light tan, red, pink, green, yellow, or a combination of these and other colors. The bodies of some species are shiny and reflect rainbowlike patterns. Their body shapes also vary and usually reflect their lifestyles. Active species, such as those that hunt for their food and some burrowers, have bodies with segments that are all very similar in appearance to one another. They have well-developed flaplike appendages, eyes, and other sensory organs. Some of these species have a mouth with tough jaws and the ability to extend part of their digestive tract outside the body to feed. Less active species, such as those living in tubes in sand or mud or in permanent burrows, have distinct body regions, each specialized to perform a certain job. Their fleshy side flaps are sometimes greatly reduced, even absent. Their mouths have tubes with special tentacles that help them to gather food.