The Muraenidae family of morays is the most infamous group within the order Anguilliformes, which are jawed fish called eels. They constitute a family of more than 80 species, occurring in greatest abundance in tropical and subtropical waters. The typical moray’s body is flattened from side to side, pectoral fins are lacking, and the scaleless skin is thick and leathery. The dorsal and the anal fins are low, sometimes almost hidden by the wrinkled skin around them. The gill opening is small and round, and the teeth are large. Most morays are large, reaching a length of 5 to 6 feet. Some are as long as 10 feet.
Normally, morays are nocturnal, but they never miss an opportunity to appear from their rocky lairs when a meal is in the offing. They feed on small fish, octopus, crustaceans, and mollusks.
The green moray (Gymnothorax funebris), which lives in tropical and subtropical waters of both North and South America and averages 5 to 6 feet long, is an unusual brownish-green, due to a yellow slime that covers the eel’s blue body. The green moray inhabits coral reefs, sometimes
going into deep water to prowl for food. The spotted moray (G. moringa) occurs in the same
range as the green moray. It is usually under 3 feet long and has prominent dark spots or a chainlike pattern of dark lines on its usually yellowish body.
The California moray (G. mordax) is similar in appearance and habits to the spotted moray. It grows to 5 feet, is found up to 65 feet deep, and may live more than 30 years. The blackedge moray (G. nigromarginatus), prevalent in the subtropical Atlantic, the Caribbean, and the Gulf of Mexico, is of similar size, but the black pattern is more pronounced, with black margins on the dorsal and the anal fins.
Morays live primarily in coral reefs or in similar rocky areas. A moray will anchor the rear half of its body in coral and rocks, allowing the front of its body to sway with the current.
In this position, with its mouth agape, it is ready to grasp any prey that comes close. This gaping stance appears menacing, but it is an adaptation suited not only to foraging but also to respiration, allowing the eel to pump water across its gills.