Jointed-Tube Worm (Spiochaetopterus costarum)
"Look at all the sticks in the mud," some McKenny Elementary School fifth-graders shouted as they explored the tideflats.
These kids were experiencing a local beach at low tide under the guidance of expert instructors of the Thurston Conservation District's South Sound Green program, led by Anne Mills.
What they had found was a large colony of polychaete worms that live in leathery tubes encircled with regularly spaced rings. The tubes, which stick 1 to 2 inches above the sediment, are about 1/16 inch in diameter and are buried 8 to 10 inches deep.
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The worm spends its life within the protection of the tube. Its body is made up of different sections, with the head featuring two long feeding tentacles called palps, which use mucus to collect food from the sand surface and probably the water as well. The other body sections feature flaps for moving water within the tube. The worms can withdraw deep in the tubes to avoid predators or surface disturbances.
This species occurs below the mid-tide level in muddy sand to sandy beaches. It ranges worldwide in the Northern Hemisphere. It is common from Puget Sound north.
David W. Jamison is a marine biologist and Boston Harbor resident.