Home › Sea Life Facts › Marine Species › Vertebrates › Moray Eels › Anatomy

Facts about the Body Parts of Moray Eels

Not only does the moray eel anatomy help them ambush their favourite prey (small fishes), it also means they can hide in crevices and wait patiently to strike.

The information in this segment explains the physiological and physical characteristics of moray eels, including how their internal organs and different body parts work.

The Unique Internal Anatomy of Moray Eels

Some of the distinctive features and characteristics of morays (family Muraenidae) come from several adaptations to their environment.

For example, there aren't many large predatory fish that can squeeze themselves into tiny spaces and lie in wait like moray eels do.

Here's the thing:

In general, moray eels live solitary lives and can be quite territorial.

They conceal themselves in coral reef formations and among shallow rocky crevices.

Even though you might describe their appearance as "snake-like", in fact moray eels are fish - albeit without the typical pectoral and pelvic fish fins.

Hence, much like the two hundred species of snake eels, the physical and physiological characteristics of morays underline their laterally compressed and somewhat serpentine body shape.

Composition of a Moray Eel

Snakelike Body Shape

Moray eels have an elongated muscular body form that allows them to navigate the tight spaces and crevices of reef terrains and sloping or shelving ocean environments.

Because most don't have pectoral and pelvic fins, a laterally compressed physique, along with a streamlined eel-like appearance, is ideal for maneuvering around marine ecosystems and swimming in "benthic zones" of tropical and subtropical seas.

The cartilaginous skeleton contains up to two hundred (200) vertebrae in some species of moray eels. As a result, they are extremely flexible and agile for a long and slender fish.

For example:

One of the longest morays is the slender giant moray (Strophidon sathete), which can grow up to four (4) metres in total body length.

Almost all moray eels have a large head and powerful, muscular jaws. The fang-like teeth curve backwards and they are extremely sharp - used for grasping and immobilising slippy prey, such as the slippery dick fish wrasse, gobies, and blennies.

Having the second set of "pharyngeal jaws" at the back of their throat is one of the unique features. They use this forward-moving mechanism to pull unsuspecting victims into the esophagus, and then into the digestive tract.

Moray Eel Digestion System

The digestive tract is quite short for such an elongated and slender marine animal.

Nonetheless, the digestive tract and stomach acids meet the needs of these carnivorous predators, which often includes:

Cephalopods (e.g. octopus, squid)
Saltwater crustaceans (e.g. crabs, shrimps)
Red Lionfish (Pterois volitans)
Carrion (decaying or dead fish flesh)

Skin, Scales, and Fins

Because most moray eels lack scales (bony plates), the skin is smooth and thick. On top of that, the epidermis is covered in a slimy toxic mucus that acts as a defencive layer against parasites and skin abrasions.

The dorsal fin is continuous, and begins slightly behind the head. It runs along the back and eventually merges "seamlessly" with the caudal and anal fins.

Put another way, the absence of paired fins means morays have greater flexibility and they are able to produce balanced and stable undulating movements that help with propulsion.

Body Colouring

The body colouration varies between the different types of moray eel. For example, some have solid colours, and others have stripes or spots (even inside the mouth) that create extra camouflage among rocky outcrops.

Head, Eyes, and Sensory Organs

Unlike most vertebrate fish families, the narrow head causes a problem for morays when swallowing food through the normal method (e.g. negative pressure suction feeding).

Even though the eyes are set forward and provide binocular vision, they are mostly small with low visual acuity.

Because the vision for moray eels is quite poor, they use their eyes for detecting movements rather than accurate detailing.

But wait - there's more:

The snout contains two (2) sets of smell-based nostrils (known as the anterior and posterior "nares") that they use for hunting.

Despite the small brain size, moray eels are nocturnal apex predators that are quite intelligent for a fish. Moreover, having an acute sense of smell is essential for locating food sources during the darkness or in murky water.

Gills and Respiratory System

Morays have two small, circular gill slits or openings situated behind their narrow head. Even though it may look aggressive, like they are constantly biting something, the reason they continuously open and close their mouths is to create constant water flow - by pumping water over the gills for respiration.

Reproductive Organs

The sex organs of moray eels are part of their internal anatomy - not visible on the outside. Even though most of the species have a single gonad, others have a combination of ovary and testis tissue.

Pro Tip: The main section contains more information about moray eel reproduction, including the average lifespan and current conservation status.