Description

The bowmouth guitarfish is a heavily built fish growing to 2.7 m (8.9 ft) long and 135 kg (298 lb) in weight. The head is short, wide, and flattened with an evenly rounded snout; the front portion of the head, including the medium-sized eyes and large spiracles, is clearly distinct from the body. The long nostrils are transversely oriented and have well-developed skin flaps on their anterior margins. The lower jaw has three protruding lobes that fit into corresponding depressions in the upper jaw. There are around 47 upper and 50 lower tooth rows arranged in winding bands; the teeth are low and blunt with ridges on the crown. The five pairs of ventral gill slits are positioned close to the lateral margins of the head. The body is deepest in front of the two tall and falcate (sickle-shaped) dorsal fins. 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 of the bowmouth guitarfish 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.

Fun Facts

The bowmouth guitarfish 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 such as crabs and shrimp; bivalves and cephalopods are also consumed. Its bands of flattened teeth allow it to crush hard-shelled prey. Curiously, two bowmouth guitarfishes examined in a 2011 stable isotope study were found to have fed on pelagic rather than demersal animals, in contrast to previous observations