Latin name

Mobula birostris

Other names

Giant manta ray, oceanic manta ray.

Identification

Huge pectoral fins form a diamond-shaped disc with the head, the width of which is about 2.2 times the length, reaching 9 metres in large individuals, although the average does not exceed 4.5 metres. Representatives of this subfamily are the only vertebrates with three pairs of functional limbs. The distance from the tip of the tail to the cloaca is approximately equal to the distance from the cloaca to the tip of the snout. The tail is slightly flattened and slightly shorter than the disc. The snout is slightly concave between the head fins. The snout is very wide and, unlike other members of the subfamily, is located at the front of the head rather than underneath it. The eyes are located on the sides of the head, and 5 pairs of gill slits - five on each side - are located on the underside of the head.  Teeth are arranged in rows on the lower jaw only. The number of rows decreases from 18 in the centre to 12-14 at the corners of the mouth. The spine on the tail is absent.

Features of fish fins

The front part of the pectoral fins becomes the so-called dorsal fins. The length of the dorsal fin is 2 times the width of its base.  At the base of the tail there is a small dorsal fin, the height of which is about 83% of the length of the base, which in turn is 34% of the width of the mouth.

Fish colouring

Dorsal surface of disc dark grey, dark brown or black, ventral surface pale. Bright white spots on the upper part of the dorsal surface of the disc are hook-shaped and directed towards the head fins. The front edge of these spots is parallel to the mouth opening. There are no black spots or markings between the gill slits. A broad dark grey band runs along the edge of the ventral surface of the disc. The mouth area is dark grey or black. Some individuals are almost entirely black except for a bright white patch on the underside of the disc. There is a small projection at the tip of the tail. Each individual has a unique body colouration which allows them to be identified. There are conical or ridge-shaped spots scattered on both sides of the disc.

Sailing speed

Can swim at speeds of up to 30 km/h.

Distribution

Widespread but fragmented distribution in tropical, subtropical and temperate waters of the Pacific, Atlantic and Indian Oceans between 35°N and 35°S. In the Northern Hemisphere their range extends to southern California, occasionally they are found off the coast of New Jersey and San Diego, common in the Gulf of Aden, the Bay of Bengal, the Red Sea, in the Northwest Pacific they inhabit the waters of Japan and in the Atlantic near the Azores. In the southern hemisphere, they can be found off the coasts of Peru, Uruguay, South Africa and New Zealand.

Habitat

They lead a pelagic lifestyle. They can go below 1000 metres. They stay in coastal waters in spring and autumn and swim out to sea in winter. During the day they often stay close to the surface in shallow waters and at night they go to the depths.

Size

It is the largest of the stingrays, with individuals reaching 9.1 metres in length (4-4.5 metres in bulk). The maximum recorded mass is about 3 tonnes.

Behavior

They often form small flocks of less than 30 individuals while feeding, breeding and cleaning parasites.

They make long migrations of up to 1100 km, but rarely cross the ocean. 

They swim by flapping their pectoral fins like wings. In the open sea they move at a constant speed in a straight line, and near the shore they often bask on the surface or circle lazily. They are often accompanied by other fish, sea birds and mammals.

When feeding, the fish swim slowly around their prey, compressing it into a mass, then accelerate and swim through the cluster of organisms with their mouths open. The head fins, which are usually spirally coiled into a tube, unfold during feeding. These are used to guide food into the mouth. In the presence of exceptionally large concentrations of food, they can, like sharks, go into a feeding frenzy.

Food and feeding habits

They are filter feeders. The filtering mechanism consists of pinkish-brown spongy plates between the gill arches. The diet is based on zooplankton and fish larvae. Can feed on small fish. Fish travel long distances in search of food, constantly following the movement of plankton. They find food by sight and smell. The mass of food eaten by an individual each week is about 13% of its own mass. 

Reproduction

Reproduction by oviparity. Fertilisation is internal. Males reach sexual maturity at the age of 5-6 years with a disc width of 4 m and females with 5 m. During the breeding season (December-April) they display a peculiar mating behaviour. First, the male and sometimes several males chase the female for 20-30 minutes. Then the male approaches the female, grabs her by the edge of the pectoral fin and turns her over. Mating takes place in the upper layers of the water. After turning the female over on her belly, the male inserts one of his pterygopodia into the female's cloaca. Fertilisation takes 60-90 seconds. A single female can be fertilised by one or two males. The eggs are incubated in the female's body and hatch internally. The embryo first receives nutrients from the reserves in the yolk sac and then additional nutrients from the maternal body through indirect absorption of royal jelly, which is rich in mucus, fats and proteins. Embryonic development takes about a year. The female gives birth to one or, less frequently, two young. The width of the intervertebral discs of newborn cubs ranges from 1.1 to 1.3 m, and their weight varies from 9.1 to 12.7 kg. Births take place in shallow water, where the young fatten up for several years.

Fishing

They are not fished, but caught as by-catch.  

Relationship with a person

The species is not dangerous to humans. 

Exhibited in oceanariums.