Moray eels are in the Muraenidae family and are a fairly diverse group of eels of approximately 200 species. They differ greatly in coloration and size. The largest the Giant Moray Eel can reach up to 3 meters in length and can weigh 30 kilograms. The smallest eels are just over 12 centimeters in length.
Some such as the Zebra Moray Eel below are attractively marked .
In terms of looks though the Ribbon eel pictured below probably takes the first prize amongst Moray eels.
Moray eels have rather fearsome looking teeth and not only do they have teeth around the edge of the jaw, the often have additional rows of teeth on their upper palate. Generally the teeth of a moray eel are designed for seizing prey rather than chewing it. These extra teeth can be seen in the image below.
Moray Eels also have a second set of jaws in their throats called pharyngeal jaws. Once the prey has been seized by the mouth the second set of jaws moves forward and pulls the prey into the stomach.
To make up for the lack of chewing teeth, a moray eel will often seize its prey and then tie its self in a knot, pushing the knot down its body. Once the knot reaches the prey this allows the moray to push on the knot and apply pressure onto the prey. Pieces of the prey can then be ripped off using the strength of its body.
Some smaller morays such as the Geometric Moray below prey on mollusks and crustaceans. Their teeth are rounded rather than sharp and are used to grind the prey. They are however still capable of giving a painful bite.
Moray Eels have small gills and are nearly always constantly opening and closing their mouths to facilitate the flow of water over their gills. This opening and closing of their mouths is not a threat display. They should however always be treated carefully and one should not approach too closely. They can give a very painful bite.
Usually as Moray eels age their head becomes thickened and once they have reached a certain length they thicken rather than growing longer.
Many Moray Eels are mainly nocturnal feeders and only come out of their holes at night. Often on night dives they can be seen out feeding.