Spotted eagle ray

Spotted eagle ray
Conservation status
Near Threatened  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Myliobatiformes
Family:	Myliobatidae
Genus:	Aetobatus
Species:	A. narinari
Binomial name
Aetobatus narinari (Euphrasen, 1790)
Synonyms
Aetobatis latirostris Aetobatis narinari Aetomylus maculatus Myliobatis eeltenkee Myliobatis macroptera Myliobatus punctatus Raia quinqueaculeata Raja narinari Stoasodon narinari

The spotted eagle ray, Aetobatus narinari, Euphrasen (1790), or bonnet ray, is a cartilaginous fish found in shallow coastal water by coral reefs and bays, in depths down to 80 meters (260 feet). They are members of the eagle ray family, and can be found globally in tropical regions, including the Gulf of Mexico, Hawaii, Atlantic Africa, the Indian Ocean, Oceania, and the Pacific west coast of the Americas. The spotted eagle ray can be identified by its numerous white spots or rings on its blue dorsal surface, white ventral surface, long, whip-like tail, and distinctive head that somewhat resembles a bill. It preys mainly upon bivalves, shrimps, crabs, whelks, and other benthic infauna. The spotted eagle ray's specialized chevron-shaped tooth structure helps it crush the hard shells of mollusks. The largest specimens can grow up to a maximum wingspan of 3 m (10 ft) and a mass of 230 kg (500 pounds). It has a notably long tail in relation to other rays; the total length of a mature ray can reach 5 m. It can have up from 2–6 venomous spines on the tail, however, it does not pose a significant threat as it generally avoids human contact. A. narinari develops ovoviviparously—the eggs hatch internally and feed off a yolk sac prior to birth.

Taxonomy

The spotted eagle ray was described at first as Raja Narinari in 1790. It was later changed to Stoasodon Narinari. It's current name is the Ateobatus Narinari. The name is derived from the Greek words aetos, which means eagle, and batis which means ray. The spotted eagle ray is a part of the family Myliobatidae. Most animals in the Myliobatidae swim in open ocean rather than on the sea floor. This family consists of a wide variety of rays.

Description and behavior

Reproduction

In spotted eagle rays, one male, or sometimes more than one, will pursue a female. When the male approaches the female, he uses his upper tooth plate to grab on to her dorsum. The male will then roll the female over by grabbing her pectoral fin. After she is on her ventral side, the male will put a clasper into the female. They will be connected venter to venter. The mating process can last anywhere from thirty to ninety seconds.

Feeding and diet

The spotted eagle rays feed on mollusks and crustaceans, particularly malacostracans. The rays eat bivalves, which are animals with two shells, and gastropods like snails and slugs. Studies have shown that there are not any differences in the feeding habits of males and females or in rays from different reigions.

Behavior

Studies have shown that these rays movement is influenced by the tides. One tracking study results showed that the A. narinari was more active during high tides. The spotted eagle ray prefers to swim in waters of 24-27 degrees Celsius. These rays have several distinctive behaviors that have been observed. The spotted eagle ray is known to dig, with its snout, in the sand of the ocean. While doing this, a cloud of sand surrounds the ray and sand spews from its gills. Also, the spotted eagle ray exhibits two motions in which the abdomen and the pectoral fins are moved rapidly up and down. These are called the pelvic thrust and the extreme pelvic thrust. The pelvic thrust is usually one ray alone and done four to five times rapidly. The extreme pelvic thrust is most commonly observed when the ray is swimming in a group. It will separate itself from the group and do a large thrust of its pectoral fins. The ray also does dips and jumps. Dips take place when the ray dives downward and then back up rapidly. They often do this one to five times in a row. As for jumping, there are two main types of jumps. One is a vertical jump, where the ray propels itself directly vertical out of the water and then back in the same way. The other jump is when the ray leaps and a 45 degree angle. This jump is often repeated multiple times in a row at high speeds. As for the rays social interactions, there are several ways they congregate. The rays are found swimming alone and also in schools. The rays are most commonly seen alone in shallow waters or outside their normal swimming areas. One form of traveling is called loose aggregation. This takes place when three to sixteen rays are swimming in a loose group, with an occasional interaction between the rays. The common school consists of six or more rays swimming in the same direction at the exact same speed.

Predators

The spotted eagle ray, along with many other rays, falls victim to many sharks. Among these sharks are the tiger shark, the lemon shark, the bull shark, the silver tip shark, and the great hammerhead shark. The spotted eagle rays are particularly defenseless to sharks because of their short stingers.

Habitat and distribution

The spotted eagle rays can be found in warm, temperate, waters worldwide. In the waters of the West-Atlantic Ocean, it can be found of the coast of North Carolina, 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 in South Africa to northern Japan and Australia. The ray can also be found in the Eastern-Pacific Ocean from the Gulf of California down through Puerto Pizzaro (this includes the Galapagos Islands). The spotted eagle ray is most commonly seen in bays and reef areas. It spends much of its time swimming freely in open waters. These rays generally swim in schools, staying close to the surface of the water. They can travel long distances of open ocean each day.

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