The burying behavior observed in all darters of the genus Ammocrypta has been described as a technique to: 1) avoid predators; 2) enhance prey-capturing abilities; or 3) conserve energy. I tested these three hypotheses experimentally with specimens of Ammocrypta pellucida held in an artificial stream system. When burying themselves, individual A. pellucida consistently plunged headfirst and completely covered themselves with sand. Tests showed that this species did not bury itself to increase its ability to capture prey; nor did the proximity of predators consistently elicit the burying response. The hypothesis of energy conservation is not rejected, but may be incomplete. I suggest that this darter plunges to maintain its position on the relatively homogeneous sand beds on which it lives. Although the behavior is exhibited at any time and during any season, it is probably of high survival value only during periods of extremely high or low flow.