Since there is less of a need to excrete excess salts in a fresh water environment, freshwater elasmobranchs have adapted decreased size and function in their rectal glands. Living prey of any species give off characteristic electrical potentials which can be detected by the ampullae of Lorenzini. Feeding behavior involves the ray slowly swimming approximately 0.1 - 0.2 m above the surface of sand bottoms, followed by abrupt stops to evaluate an area for the presence of prey items. To inspect an area, the ray lies motionless on top of the sand. If prey is detected, the ray begins an undulatory movement of its pelvic fins to mechanically excavate prey from the benthos.
Excavation creates a feeding depression which helps retain prey.
Deep dwelling prey such a polychaete worms are further exposed by increased mouth suction. Competes for benthic prey with other ray species and with fishes that feed on similar prey items. Preferred habitat areas have bottoms of sand or silt, and include shoreline, spoil islands, and seagrass beds. D. sabina exhibits pronounced seasonal movement patterns. From Spring through Fall, it is typically found in inshore shallows.