IT COMES in a stunning array of colours, with a slippery mucus-covered body and a head full of glistening white razor-sharp teeth. At first sight, a moray eel can send shivers down your spine, but once you begin to understand this much-maligned creature, you could well grow to love it.
Morays, classified under the family name Muraenidae, are probably the most diverse and widely distributed of eels. They are found in all tropical seas, usually in shallow waters, and there are thought to be as many as 200 species worldwide.
Identifying a moray is fairly easy. Although each species tends to have distinct colours and markings, they all have smooth muscular bodies covered in scale-less skin, with a protective layer of mucus. They have no pectoral or ventral fins and their dorsal, tail and anal fins are merged into one long fin down the back.
Most morays grow to a metre or so in length but some species can reach over 3m. They are generally shy and reclusive creatures, spending most of their time sheltering under a favourite ledge or hole in the reef; but when they choose to swim out in the open, they make an impressive sight indeed.
To breathe, a moray needs to pump water through its mouth and over its gills. To do so it must continually open and shut its mouth, revealing a set of threatening teeth. This can mislead new divers into thinking morays are aggressive when in fact they will often retreat further into their holes when approached.
However, you may come across a moray that will open its mouth as wide as possible in an aggressive gesture. For example, the yellow-mouth moray - Gymnothorax nudivomer - does this to reveal its brightly-coloured mouth as part of a natural defence mechanism.
We are only just beginning to unravel the secrets of the moray, and there is still much to learn. Many morays are thought to start life as males, and change into females as they get older - rather like some other species of fish, like Britain's cuckoo wrasse. Little is known about moray mating habits but they do pair off in season and share the same territory. Otherwise morays prefer to command their own distinct territory.
During reproduction the moray's eggs are released into the water where they develop into ribbon-like, transparent larvae that drift with the plankton for up to a year before transferring to the reef floor as miniature eels.
Most morays are thought to be nocturnal but some are known to hunt during the day. They feed mostly on fish, crustaceans and octopus, but they tend to be opportunists and will always pinch a meal if they can.
In some locations diving activity has inadvertently changed the moray's feeding habits by enticing the creatures out by day when they were used to hunting at night. At Stingray City in the Cayman Islands, dive guides had to stop feeding the morays when they became too bold and several divers were bitten. Their hands were mistaken for food - these creatures have surprisingly poor eyesight.
A moray feeds like a snake, ambushing its prey with a quick strike, grabbing and holding it in its extremely strong jaws before swallowing it whole. Generally a messy eater, it requires constant cleaning. Cleaner wrasse and shrimp are never far away and can often be seen disappearing inside an eel's mouth, only to reappear a few seconds later.
If you are unlucky enough to get bitten by a moray you could end up with a painful wound that is liable to go septic.
Ciguatoxins are thought to be produced by a certain algae which is eaten by herbivorous fish. Morays then eat these fish and their flesh becomes toxic. Several people are known to have died from eating morays containing these toxins. Be warned that they cannot be removed through normal cooking.
Warnings aside, morays are wonderful creatures to watch. The next time you see one, settle down on the seabed for a few minutes, and you will be treated to a fascinating display of their behaviour.