A Shelly Worm Tube
Early this week, Museum staff member Austin Salender found a 40 mm (about 1.6 inch) piece of a Plumed or Ornate Worm (Diopatra cuprea) tube (photo), during one of the Museum’s Beach Walks at Island Inn on Sanibel. Pieces of Plumed Worm tubes are common on our beaches. They are usually covered with seaweed, shell fragments, tiny pebbles, sand grains, pieces of coral, and other marine debris that the worm picks up from its environment and attaches to its tube, which consists mostly of polyssacharides (compounds that form starch in plants, “animal starch” in animals.) The tube is “J”-shaped, and can be as long as one meter (about three feet). The piece that Austin found was covered mostly with valves of the bivalve Angulus probrinus, also known as the Slandered Tellin. The reason for the choice of a particular kind of molluscan shell is unknown, but it is clear that the worm chooses to cover its tube with objects of consistent size, shape, and weight. In a paper published in 2008, Sarah Berke from the University of South Carolina and collaborators ruled out the hypothesis that affixing objects such as shells on their tubes helps camouflage the worms against predators.