Moray Eel

The polygon moray, Gymnothorax polygonius, is a moray eel of the family Muraenidae, found in the eastern Atlantic from Madeira and Cape Verde, and the western central Atlantic from Cuba and the Trindade Island (Brazil), at depths down to 50 m, in coastal waters. Its length is up to 84 cm (33 in).

The approximately 200 species in 15 genera are almost exclusively marine, but several species are regularly seen in brackish water, and a few, for example the freshwater moray, can sometimes be found in freshwater.

The largest in terms of total mass is the giant moray (Gymnothorax javanicus), which reaches 3 m (9.8 ft) in length and 30 kg (66 lb) in weight.

Moray eels' heads are too narrow to create the negative pressure most fishes use to swallow prey. Quite possibly because of this, they have a second set of jaws in their throat called pharyngeal jaws, which also possess teeth. When feeding, morays launch these jaws into the mouth, where they grasp prey and transport it into the throat and digestive system. Moray eels are the only animals that use pharyngeal jaws to actively capture and restrain prey. Larger morays are capable of seriously wounding humans.

Morays secrete a protective mucus over their smooth, scaleless skin, which in some species contains a toxin. Morays are carnivorous and feed primarily on other fish, cephalopods, molluscs, sea snakes, and crustaceans. Groupers, barracudas and sea snakes are among their few predators. Commercial fisheries exist for several species, but some cause ciguatera fish poisoning.

Morays are frequently thought of as particularly vicious or ill-tempered animals. In truth, morays hide from humans in crevices and would rather flee than fight. They are shy and secretive, and attack humans only in self-defence or mistaken identity. Most attacks stem from disruption of a moray's burrow (to which they do react strongly), but an increasing number also occur during hand-feeding of morays by divers, an activity often used by dive companies to attract tourists. Morays have poor vision and rely mostly on their acute sense of smell, making distinguishing between fingers and held food difficult; numerous divers have lost fingers while attempting hand feedings, so the hand feeding of moray eels has been banned in some locations.

The moray's rear-hooked teeth and primitive but strong bite mechanism also makes bites on humans more severe, as the eel cannot release its grip, even in death, and must be manually pried off. While the majority are not believed to be venomous, circumstantial evidence suggests a few species may be.

Moray eels are cosmopolitan, found in both tropical and temperate seas, although the largest species richness is at reefs in warm oceans. Very few species occur outside the tropics or subtropics, and the ones that do only extend marginally beyond these regions. They live at depths up to several hundred metres, where they spend most of their time concealed inside crevices and alcoves. While several species regularly are found in brackish water, very few species can be found in freshwater, for example, the freshwater moray (Gymnothorax polyuranodon) and the pink-lipped moray eel (Echidna rhodochilus).