Photo by Mika d’Eau
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 other rays and may have 2–6 venomous spines, behind the pelvic fins. The front of the wing-like pectoral disk has five small gills in its underside.
Mature spotted eagle rays can be up to 5 meters (16 ft) in length; the largest spotted eagle rays have a wingspan of up to 3 meters (10 ft) and a mass of 230 kilograms (507 lb). However, the ones we encounter in the Maldives are usually not larger than 1,5m
Spotted eagle rays prefer to swim in waters of 24 to 27 °C (75 to 81 °F). They are commonly found in the Maldivian channels.
They are found in shallow coastal water by coral reefs and bays, in depths down to 80 meters (262 ft). Spotted eagle rays are most commonly seen in bays and reefs. They spend much of their time swimming freely in open waters, generally in schools close to the surface or in channels and can travel long distances in a day.
Recent authorities have split the different types of eagle rays into three categories: This restricts the true spotted eagle ray (A. narinari) to the Atlantic, while the Indo-Pacific population is the ocellated eagle ray (A. ocellatus) and the East Pacific is the Pacific white-spotted eagle ray (A. laticeps).
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. 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 travelling 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. We are blessed in the Maldives to commonly see groups of more than 20 individuals.
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 back. The male will then roll the female over by grabbing one of her pectoral fins, which are located on either side of her body. 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 17–35 centimeters (6.7–13.8 in) across. The rays mature in 4 to 6 years.
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 new born pups.
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.
Photo by Mika d’Eau
