Spotted eagle ray

Appearance

Spotted eagle rays have flat disk-shaped bodies, deep blue or black with white spots on top with a white underbelly, and distinctive flat snouts similar to a duck's bill. Their tails are longer than those of other rays and may have 2–6 venomous spines, just behind the pelvic fins. The front half of the long and wing-like pectoral disk has five small gills in its underside.

Mature spotted eagle rays can be up to 5 meters in length; the largest have a wingspan of up to 3 meters and a mass of 230 kilograms .

Distribution

Spotted eagle rays are found globally in tropical regions, including the Gulf of Mexico, Hawaii, Atlantic Africa, the Indian Ocean, Oceania, and the Pacific west coast.

They are found in shallow coastal water by coral reefs and bays, in depths down to 80 meters .
Spotted eagle rays are found in warm, temperate, waters worldwide; in the West-Atlantic Ocean, off the coast of North Carolina and down to Florida, in the Gulf Stream, in the Caribbean, and down past the southern part of Brazil. In the West-Pacific Ocean, it can be found from the Red Sea to South Africa and also in northern Japan and Australia. The ray can also be found in the Eastern-Pacific Ocean from the Gulf of California down through Puerto Pizarro, an area that includes the Galapagos Islands. Spotted eagle rays are most commonly seen in bays and reef areas. They spend much of their time swimming freely in open waters, generally in schools close to the surface, and can travel long distances in a day.

Status

The spotted eagle ray is included in the IUCN's Red List as "near threatened". The rays are caught mainly in Southeast Asia and Africa. They are also common in commercial marine life trade and are displayed in aquariums. Among the many efforts to help protect this species, South Africa's decision to deploy fewer protective shark nets has reduced the number of deaths caused by entanglement. South Africa has also placed restrictions on the number of rays that can be bought per person per day. In the state of Florida in the United States, the fishing, landing, purchasing and trading of spotted eagle ray is outlawed. The spotted eagle ray is also protected in the Great Barrier Reef on the eastern coast of Australia.

Behavior

Spotted eagle rays have flat disk-shaped bodies, deep blue or black with white spots on top with a white underbelly, and distinctive flat snouts similar to a duck's bill. Their tails are longer than those of other rays and may have 2–6 venomous spines, just behind the pelvic fins. The front half of the long and wing-like pectoral disk has five small gills in its underside.

Mature spotted eagle rays can be up to 5 meters in length; the largest have a wingspan of up to 3 meters and a mass of 230 kilograms .Spotted eagle rays prefer to swim in waters of 24 to 27 °C . Their daily movement is influenced by the tides; one tracking study showed that they are more active during high tides. Uniquely among rays they dig with their snouts in the sand, surrounding themselves in a cloud of sand that spews from their gills. They also exhibit two motions in which the abdomen and the pectoral fins are moved rapidly up and down: the pelvic thrust and the extreme pelvic thrust. The pelvic thrust is usually performed by a solitary ray, and repeated four to five times rapidly. The extreme pelvic thrust is most commonly observed when the ray is swimming in a group, from which it will separate itself before vigorously thrusting with its pectoral fins. The rays also performs dips and jumps; in a dip the ray will dive and then come back up rapidly, perhaps as many as five times consecutively. There are two main types of jump: in one, the ray propels itself vertically out of the water, to which it returns along the same line; the other is when the ray leaps at a 45 degree angle, often repeated multiple times at high speeds. When in shallow waters or outside their normal swimming areas the rays are most commonly seen alone, but they do also congregate in schools. One form of traveling is called loose aggregation, which is when three to sixteen rays are swimming in a loose group, with occasional interactions between them. A school commonly consists of six or more rays swimming in the same direction at exactly the same speed.

Habitat

Spotted eagle rays are found globally in tropical regions, including the Gulf of Mexico, Hawaii, Atlantic Africa, the Indian Ocean, Oceania, and the Pacific west coast.

They are found in shallow coastal water by coral reefs and bays, in depths down to 80 meters .
Spotted eagle rays are found in warm, temperate, waters worldwide; in the West-Atlantic Ocean, off the coast of North Carolina and down to Florida, in the Gulf Stream, in the Caribbean, and down past the southern part of Brazil. In the West-Pacific Ocean, it can be found from the Red Sea to South Africa and also in northern Japan and Australia. The ray can also be found in the Eastern-Pacific Ocean from the Gulf of California down through Puerto Pizarro, an area that includes the Galapagos Islands. Spotted eagle rays are most commonly seen in bays and reef areas. They spend much of their time swimming freely in open waters, generally in schools close to the surface, and can travel long distances in a day.

Reproduction

One male, or sometimes several, will pursue a female. When one of the males approaches the female, he uses his upper jaw to grab her dorsum. The male will then roll the female over by grabbing one of her pectoral fins, which are located on either side of her body. Once she is on her ventral side, the male puts a clasper into the female, connecting them venter to venter, with both undersides together. The mating process lasts for 30–90 seconds.

The spotted eagle ray develops ovoviviparously; the eggs are retained in the female and hatch internally, feeding off a yolk sac until live birth. After a gestation period of one year the mother ray will give birth to a maximum of four pups. When the pups are first born, their discs measure from 170–350 millimeters across. The rays mature in 4 to 6 years.

Food

Spotted eagle ray preys mainly upon bivalves, shrimps, crabs, whelks, and other benthic infauna. They feed on mollusks and crustaceans, particularly malacostracans. and also upon hermit crabs, shrimp, octopi, and some small fish.

The spotted eagle ray's specialized chevron-shaped tooth structure helps it to crush the mollusks' hard shells. The jaws of these rays have developed calcified struts to help them break through the shells of mollusks, by supporting the jaws and preventing dents from hard prey. These rays have the unique behavior of digging with their snouts in the sand of the ocean. While doing this, a cloud of sand surrounds the ray and sand spews from its gills. One study has shown that there are no differences in the feeding habits of males and females or in rays from different regions of Australia and Taiwan.

Predators

Spotted eagle rays, in common with many other rays, often fall victim to sharks such as the tiger shark, the lemon shark, the bull shark, the silver tip shark, and the great hammerhead shark. A great hammerhead shark has been observed attacking a spotted eagle ray in open water by taking a large bite out of one of its pectoral fins, thus incapacitating the ray. The shark then used its head to pin the ray to the bottom and pivoted to take the ray in its jaws, head first. Sharks have also been observed to follow female rays during the birthing season, and feed on the newborn pups.