Phylum: Chordata
Class: Chondrichthyes
Order: Rajiformes
Family: Rhinidae
Genus: Rhina
Species: Rhina ancylostoma
Common Names: Bowmouth guitarfish, Mud skate, Shark ray
The shark ray is a species of ray that is closely related to guitarfishes and skates. It is widely distributed over the tropical coastal waters of the Indo-Pacific region in depths of up to 90 meters (300 feet). They are the sole member of the family Rhinidae.
Shark Ray Habitat
Shark rays ray can be found in the Indo-west Pacific, East Africa (Red Sea to South Africa) to Papua New Guinea, north to Japan, across northern Australia from Exmouth Gulf in Western Australia to New South Wales Generally the species prefers sandy or muddy habitats, however it can occasionally be found in rocky habitats, coral reefs and shipwrecks.
They inhabit coastal waters in depths ranging from 3 to 90 m (10–300 feet), typically dwelling on or near the sea floor bottom, although from time to time they may swim well above it.
Shark ray description
Shark rays can reach a maximum reported length of 2.9 m (8.9 feet) long and a maximum reported weight of 135 kg (300 pounds). However sightings of shark rays exceeding the length of 2.4 meters are pretty rare. Their coloration is bluish-gray on the upper side that lightens towards the head and the pectoral fins, and grayish to white on the underside. Usually there are many prominent white spots all over the body as well as a white-edged black marking above each pectoral fin along with two dark transverse bands on top of the head between the eyes. Young shark rays tend to be more vividly colored than adults do, usually having a brownish coloration with a fainter pattern and proportionately smaller black spots.
Their appearance is quite distinctive and they look like a combination of a shark, a ray and a guitarfish.
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| A female shark ray |
A thick ridge with massive and sharp thorns runs along the midline of their backs while more such “thorny” ridges can be found in front of the eyes and on the shark ray's "shoulders". These thorns are mainly employed as a means of defense.
Their tail is longer than the body and has a large, crescent-like caudal fin. The nostrils are elongated and oriented in a crosswise manner, with well-developed flaps of skin which separate each opening into inflow and outflow apertures. Their lower jaw has three protruding lobes which fit into three depressions in the upper jaw. The mouth contains 47 upper tooth rows and 50 lower teeth rows with ridged teeth arranged in winding bands. These teeth are primarily used for crushing the shells of their prey.
Shark rays have 5 pairs of gills which are found near the lateral margins of their head.
In the wild their lifespan is unknown however in captivity they have been reported to live to be up to 7 years old. Males are known to reach sexual maturity after reaching a length of 1.5–1.8 m (4.9–5.9 feet).
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Shark ray parasites
Shark rays are a common host for many parasites including the following;
- The tapeworm Tylocephalum carnpanulatum
- The trematode Melogonimus rhodanometra
- The monogeneans Branchotenthes robinoverstreeti and Monocotyle ancylostomae
- The copepod Nesippus vespa
Shark ray behavior
They are a very active species (especially during the night) with no territorial behavior ever recorded. According to a few scientists shark rays use their spiked ridges over the eyes, nape, and pectoral fins to “head-butt” potential predators and attackers, however this theory has yet to been proven.
They are a carnivorous species mainly consuming bottom-dwelling crustaceans like crabs and shrimps, however on occasions they may also feed on mollusks and bony fishes. They use their smell to locate their prey and after they do, they restrain it with their broad, blunt head easing it afterwards inside their mouth with a series of short but strong thrusts.
Their main predator and enemy is the tiger shark.
