The first dorsal fin is about a third larger than the second and originates over the pelvic fin origins. The second dorsal fin is located midway between the first dorsal and the caudal fin. The broad and triangular pectoral fins have a deep indentation where their leading margins meet the head. The pelvic fins are much smaller than the pectoral fins, and the anal fin is absent. The tail is much longer than the body and ends in a large, crescent-shaped caudal fin; the lower caudal fin lobe is more than half the length of the upper. The entire dorsal surface has a grainy texture from a dense covering of tiny dermal denticles. A thick ridge is present along the midline of the back, which bears a band of sharp, robust thorns. There are also a pair of thorn-bearing ridges in front of the eyes, a second pair running from above the eyes to behind the spiracles, and a third pair on the "shoulders". This species is bluish to brownish gray above, lightening towards the margins of the head and over the pectoral fins. There are prominent white spots scattered over the body and fins, a white-edged black marking above each pectoral fin, and two dark transverse bands atop the head between the eyes. The underside is light gray to white. Young rays are more vividly colored than adults, which are browner with fainter patterning and proportionately smaller spots. Distribution and habitat While uncommon, Rhina ancylostoma is widely distributed in the coastal tropical waters of the western Indo-Pacific. In the Indian Ocean, it is found from KwaZulu-Natal in South Africa to the Red Sea (including the Seychelles), across the Indian subcontinent and Southeast Asia (including the Maldives), to Shark Bay in Western Australia. Its Pacific range extends northward to Korea and southern Japan, eastward to New Guinea, and southward to New South Wales. Found between deep, this ray spends most of its time near the sea floor but can occasionally be seen swimming in midwater. It favors sandy or muddy habitats, and can also be found in the vicinity of rocky and coral reefs and shipwrecks. Biology and ecology Rhina ancylostoma is a strong swimmer that propels itself with its tail like a shark. It is more active at night and is not known to be territorial. This species feeds mainly on demersal bony fishes such as croakers and crustaceans