Astropecten spend much of their lives buried just under the sand, with only the tips of their arms showing. When the chemo-receptors in their arms smell food, they emerge from the sand and begin to hunt, or they move through the sand searching for buried prey.

NEFSC biological sciences technician Toni Chute cares for a collection of sand stars in the basement of the Woods Hole Science Aquarium. The animals are not kept for display, but rather to provide a glimpse into the natural history of a little-studied echinoderm.

Three years ago, in an effort to learn more about Astropecten, Hart and Chute began keeping a small collection of the stars in the basement of the Woods Hole Science Aquarium. They set up shop with 51 sand stars that came up in a dredge during the 2003 spring survey. The Astropecten that survived the trawling were a badly beat-up bunch of echinoderms.

“We had three-legged stars; we had two-legged stars; we had one that was just a middle,” Chute said. The NEFSC biologist put the stars in the aquarium’s temperate water system and began feeding them shrimp pellets, and the hardy echinoderms grew new arms and began to prosper.

Chute has been caring for the stars for three years, tracking their growth, monitoring their health, learning to identify individual animals, and observing their behavior.

At first glance, the sedentary-looking animals don’t seem to have a lot of behavior, but closer observation reveals a variety of purposeful actions. When Chute drops pellets in the water, the animals emerge from the sand and begin a stampede, with some sand star sprinters covering a foot in well under a minute. The animals also respond to changes in light, Chute reports, and periodically they lose interest in eating and develop an interest in each other.

“They make little pig piles,” Chute said. “A star will go right over the pellets to go stand on top of another star.”

The stars in the basement aren’t likely to answer the question of what role Astropecten in the wild play in determining the size of the mid-Atlantic scallop crop, but they are giving Chute and Hart some clues about how much sand stars eat, how fast they grow, and how long they can live.

Posted September 14, 2006