Fish dorso-ventrally flattened, with a rounded snout and rounded pectoral fins, which give them a disc-like shape. Back yellowish brown with numerous pale and dark spots and blotches (U. jamaicensis 2). The color can change dramatically. Mouth on the underside of the head. Tail stout with a venomous spine near the end (U. jamaicensis).
Size of the diameter of the disc, excluding the tail: 1.2 - 1.8 meter; tail nearly as long.
Inhabit sandy areas, especially around reefs. Lie on the bottom, often covered with sand, down to 25 meter.
Common Florida, occasional Bahamas and Caribbean.