South Sound Marine Life -- June 30

By David W. Jamison | For The Olympian • Published June 30, 2008

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Burrowing sea cucumber (Leptosynapta clarki)

This summer, take your children or grandchildren (or your parents or grandparents) to a local beach for some quality family time of intertidal exploration. When you do, be sure to not only look for animals on the surface, such as barnacles, sand dollars and mussels, but dig a few holes and see what kind of worms you can find. Be sure to fill in all your holes.

One wormlike critter that you might find on a sandy beach, such as Burfoot County Park, is the burrowing sea cucumber. This little fellow is about 3 inches long. It can be distinguished from polychaete worms by the white longitudinal bands of muscle running from head (or the upper left in the photograph) to tail that can be seen through the transparent skin. In addition, it lacks the body segments found in polychaetes.

Like their relatives, sea stars, sea urchins, sand dollars and brittle stars, burrowing sea cucumbers have tube feet. However, the feet only are present as modified feeding tentacles around the mouth. The body, while lacking tube feet, does possess tiny, calcareous, anchor-shaped structures in the skin that are helpful in burrowing. Unlike other larger echinoderms, they lack respiratory structures and instead absorb oxygen through their skin.

Burrowing sea cucumbers live close to the surface, where they feed on bits of organic material in the sediments. Several species range from Alaska to Southern California; however, this species seems to be most common in Puget Sound. Interestingly, this is the only species that broods its young internally.

Photo and text provided by David W. Jamison, a marine biologist and Boston Harbor resident.

South Sound marine life

A weekly look at the marine organisms of Puget Sound and the niches they fill in the ecosystem