The eagle rays are a group of cartilaginous fish that are part of the family of Myliobatidae. Eagle rays are basically large species of rays that unlike many ray species, tend to live in the open ocean rather than on the bottom of the sea.
The Genus name of this type of fish is Aetobatus which is a word derived from the Greek meaning eagle (aetos) and ray (batis).
General Description
The eagle ray has a very long tail and a well defined body that ranges from 48 centimetres to 9 meters in length. They have inky blue bodies and a long tail that can reach up to 5 meters in length. The eagle ray also has a very angular disc and a long broad snout rounded like a duck’s bill, with a “v” shaped flap.
It has a pectoral disc with sharply curved, angular corners, and no caudal fin; their jaws contain a single row of flat, chevron-shaped teeth. Each tooth is a crescent-shaped plate joined into a band.
The eagle ray swims by moving its two wings vertically – sometimes they break the surface of the sea and give the impression of two sharks traveling together. The eagle ray can also jump out and across the surface of the water.
Eating
Eagle rays feed on mollusks and crustaceans such as clams, shrimp, oysters, octopus, squids, sea urchins as well as bony fishes. They crush the shells with their flattened and very strong teeth and are very fast swimmers, which allows them to hunt efficiently. This type of ray is very well-adapted with its shovel shaped snout for searching for food in the mud for benthic invertebrates. When they find their prey, the eagle ray crushes it with its teeth and uses the papillae in its mouth to separate the shells from the flesh.
Reproduction
Eagle rays are ovoviviparous (aplacental viviparity) specimens, meaning that their eggs develop inside the body and hatch within the mother, feeding initially on yolk, then receiving additional nourishment from the mother by indirect absorption of uterine fluid enriched with mucus, fat or protein through specialized structures. They tend to give birth to up to six young at a time, whose width at birth ranges from 17-35 centimetres.
Their mating behavior consists of many male eagle rays pursuing a female. The male chases the female in mid water, then nibbles on her dorsal surface. The female stops swimming to begin copulation. The male bites the female on a pectoral fin and bends one clasper forward, then attempts an abdomen to abdomen copulation with either clasper, usually mid-water. Copulation lasted for 20 seconds to 1 minute, this makes it possible for females to mate with up to four males over a short period of time.
Where to Find The Eagle Ray
The eagle ray tends to inhabit warm, tropical waters, however they have occasionally been seen to enter estuaries. They swim close to the surface, occasionally leaping out of the water, or close to the bottom.
The eagle ray is commonly spotted swimming in bays and around coral reefs. It spends most of its time, however, swimming in schools in the open water. Eagle rays swim in big groups just below the surface where they travel very long distances, but they usually return to their original location where they interact with other eagle rays.
Eagle Rays are found on many of the dives sites of Komodo and surrounding areas. They are also found in Thailand where our Similan Liveaboard operates
Conservation
The eagle ray is considered as a “Near Threatened” species by the World Conservation Union (IUCN). However, the eagle ray is considered of minor commercial importance since the poor quality of the flesh makes it a difficult fish to eat. While eagle rays are often captured by humans, this is usually for aquarium purposes.
A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.
The eagle ray is generally considered to be a shy species wary of scuba divers and difficult to approach because they tend to swim away. Therefore they represent no real threat to scuba divers as long as they are left alone to enjoy their natural habitat without any difficulties.
Nevertheless, they are considered a potentially dangerous species due to their venomous tail spines that can inflict serious wounds if the human gets too close.
