Moray Eel

Moray Eel

Moray eels are elongated snakelike fish which are cosmopolitan, meaning they are found all around the world either in temperate or tropical seas and even in fresh water. However, the true is that their ‘favourite’ habitats are reefs or rocky areas in the warmer seas.

Therefore, as they inhabit in a variety of environments, the different species of moray eels are of different sizes and colours. They go from the Snyder’s moray of about 11.5 centimetres to the giant morays of about 3.5 metres, and have a large catalogue of skins going through the patterned to the plain and from brownish colours to blue and yellow. This is, of course, an adaptation, as it allows them to mimetize with the environment they live in. Even though, the disguising technique is not one for avoiding predators, as in other animals, but instead for hunting easily without being noticed by the unfortunate prey (the same purpose that ones from jaguars and tigers).

But despite the large range of appearances, the are a lot  of common features for all morays. The first one is their long cilindrical body, resulting as well from their necessity of blending with the environment for hunting. Thanks to this anatomy with slender body and lacking pectoral and pelvis fins morays can hide in rock cavities and coral concretions, leaving outside only their snout.

There morays will stay until a suitable prey (maybe a fish, octopus, crab or another moray; no matter if it’s dead or alive) gets near. When this happens the morays notice it with their superdeveloped sense of smell – as most of them are nocturnal and live in hidden places their eyes wouldn’t be of much help and therefore are rather small -.  Next step is catching the food. For this, morays have three rows of razor-like teeth that can as well be used for defense. But due to their shape, morays have problems swallowing. For resolving this trouble, morays had developed a second pair of jaws, pharyngeal jaws.

Pharyngeal jaws

Pharyngeal jaws

These are found in the throat and as they are retractile they can ”throw” the lunch towards the stomach.

Another common feature for all morays is the way they move. They go twisting and winding impulsed by their dorsal fin – which goes along their whole body – and the strengh of their muscular body. For helping in this task, the morays have a scaleless body covered in mucus, which allows them to swim faster as well as to hide better in complicated spaces.

A behavioral adaptation of morays are their cooperative relations with other fish. They sometimes associate with groupers for hunting together, as well, they are known to allow small cleaners such as cleaner shrimps or others to feed on the food remainders that keep in their mouths so they have a free dental cleaning.

Though, not everything in morays are facilities, these eels have some troubles which they have solved through other adaptations.

Green moray eel with open mouth.

Green moray eel. Notice the patterned interior of mouth.

For example, the already mentioned problem to swallow; or the fact that their round gills are not efffective enough. For balancing this situation the morays keep their mouth opened most of the time (in fact, it is also patterned for mimetizing), so they’re constantly creating water currents inside it for enhancing breathing effectiveness.

Those are the main adaptations of moray eels to their habitat. But, how did they evolved into their nowadays shape and characteristics ?

Well, this leads us to natural selection. As a general process, moray eels as part of anguilliformes may have developed from an early ancestor of this order. Along years, the early ancestors may have showed variation (due to mutations or sexual reproduction) between themselves. If any of these variations was favourous for the survival of the specimens with it, they would be more than the others and therefore their offspring (with the same chacteristics) would be greater in number and eventually become another specie. But there is a problem with moray eels, species develop as different advantages prove to be better for living in that concrete environment; even though, several species of moray eels are actually living in the same place with similar diets all over the world. So, how can moray eels comprise over 150 different species despite being a cosmopolitan fish? The mystery remains unsolved by now; you can read more here.

 If you want to know more about these animals  you can visit the following websites:

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