Broad Stingray - Biology and Ecology

Biology and Ecology

During the day, the broad stingray is relatively inactive and spends much time lying half-buried on the bottom. A tracking study in Kaneohe Bay found that individuals rays roamed over an average area of 0.83 km2 (0.32 sq mi) at night, compared to an average diurnal activity space of 0.12 km2 (0.046 sq mi), and did not rest consistently in any particular spot. Rays were most active two hours after sunset and before sunrise, and were more active in the higher water temperatures of summer than winter. The behavior of this species was not significantly influenced by tides, likely because they inhabit deeper water.

The broad stingray feeds mainly on bottom-dwelling crustaceans, while also taking polychaete worms and small bony fishes. It excavates large pits to uncover buried prey, and is often followed by opportunists such as jacks. Foraging rays favor areas close to reef boundaries, where many parrotfish, wrasses, gobies, and other reef fishes shelter at night. Known parasites of this species include the tapeworms Acanthobothrium chengi, Rhinebothrium hawaiiensis, Pterobothrium hawaiiensis, Prochristianella micracantha, and Parachristianella monomegacantha. Like other stingrays, the broad stingray is aplacental viviparous. Kaneohe Bay appears to be a nursery area for this species, where it and juvenile scalloped hammerheads (Sphyrna lewini) are the dominant predators.