This genus is common in the Mediterranean, and highly esteemed by the ancient Romans. It is abundantly represented in tropical and subtropical seas, especially in rocky parts or on coral reefs. In the majority, a long fin runs from the head along the back, round the tail to the vent, but all are destitute of pectoral and ventral fins. The skin is scaleless and smooth, in many species ornamented with varied and bright colours, so that these fishes are frequently mistaken for snakes.
The mouth is wide, the jaws strong and armed with formidable, generally sharply pointed, teeth, which enable the Muraena not only to seize its prey (which chiefly consists of other fishes) but also to inflict serious, and sometimes dangerous, wounds on its enemies. It attacks persons who approach its places of concealment in shallow water, and is feared by fishermen. At least one species, Muraena retifera, possesses an additional 'raptorial pharyngeal jaw' within the pharynx, which is mobile and can be thrust forwards quickly to assist in grasping prey.