Eels of the Turks & Caicos Islands

Story & Photos By C.E. O’Brien, Associate Professor of Tropical Marine Ecology, The School for Field Studies, Center for Marine Resource Studies

Eels are members of the order Anguilliformes, a group of mostly marine fishes characterized by their elongated bodies without scales. They also lack the pelvic and (usually) the pectoral fins seen in most other bony fishes and instead swim by undulating their bodies in an S-shape through the water.

This spotted moray eel has its mouth open to breathe. Opening and closing its mouth repeatedly helps pump water across the gills.

Approximately 1,000 species are part of this group, inhabiting a variety of marine habitats including coral and rocky reefs, seagrass meadows, sand flats, and even the deep sea. They range in size from as small as a few inches to as large as over a dozen feet, and almost all are solitary, nocturnal, and predators. With a wide range of prey, they play an important role in maintaining ecosystem balance:  controlling the populations of species lower on the food chain and providing energy and nutrients to larger predators above them. 

Eels hatch as leaf-shaped leptocephali larvae, floating in the ocean for days to weeks before metamorphosing into glass eels—miniature translucent versions of an adult eel. After floating for a while longer, they eventually settle to the sea bottom and assume an adult lifestyle. Lifespan varies by species, but some are known to live as long as 90 years if they are not eaten by sharks or larger bony fishes like barracudas and groupers.

Eels in the Turks & Caicos are all classified as “Not Threatened” or of “Least Concern,” although many of their habitats (like coral reefs and seagrass meadows) are at risk due to climate change, coastal development, ocean acidification, and overfishing.

The Turks & Caicos Islands are home to at least nine species of eel (that the author has seen), falling into three families:  morays, snake eels, and congers. The most familiar and common eel family in the TCI are the morays (Muraenidae), characterized by their elongated snout, lack of pectoral fins, and tendency to poke their heads out from crevices. As they do this, they often repeatedly open and close their mouths, giving some observers the impression that they are being threatened. But in fact, the moray is actually just breathing—opening and closing its mouth pumps water across its gills, allowing it to extract the oxygen it needs. 

This close-up shows the two sets of nostrils on an eel. Water enters the two tubular bumps on the front of the snout and exits through holes near the eyes.

Morays are not naturally aggressive, although they do have a mean bite. Like the Xenomorphs in the Alien movies, they have two sets of jaws:  the “normal” set of jaws at the front of its mouth, and a second set of “pharyngeal jaws” in the back of the throat that move forward during a bite to get a firmer grip on prey and pull it into the gullet. They use these terrifying teeth to hunt fishes, octopuses, and crustaceans, aided by their excellent sense of smell. This sense is superpowered by the fact that morays have two sets of nostrils:  two tube-like protuberances right above the mouth that pull water in, and holes near their eyes where water exits.

In the Turks & Caicos, snorkelers and divers are most likely to encounter spotted (Gymnothorax moringa), green (Gymnothorax funebris), purplemouth (Gymnothorax vicinus), goldentail (Gymnothorax miliaris) and chain (Echidna catenata) morays. The largest of these is the green moray, which can grow to be over 6 feet (1.8 m) long and up to 27 pounds (12.2 kg), while the others range in maximum size from a little less than 2 ft (0.6 m) to 4 ft (1.2 m). In the West Indies, the most common species is the spotted moray, which can be recognized by dark blotches on a light-colored body (or, occasionally, the reverse).

During the day, you might catch a glimpse of a head or the tail of a moray through gaps in the reef. Sometimes, you might also spot a cleaner shrimp, which like to hang out near morays in order to feast upon the food scraps and parasites that live on their skin. (See “Cleaning Stations; The 5-Star Marine Restaurant and Spa,” Times of the Islands, Spring, 2023. https://www.timespub.tc/2023/03/cleaning-stations/#:~:text=If%20a%20coral%20reef%20is,rest%2C%20relaxation%2C%20and%20rejuvenation). If you’re lucky, you may get to watch the delicate shrimp crawl over the eel’s body and even into its mouth in search of these morsels.

This sharptail snake eel is one of the most common species of snake eel in the TCI. They are shy and unaggressive, spending their days buried in sand or hiding in holes.

Occasionally, morays can be seen hunting during the day, often with other fish such as jacks and groupers. But the best time to observe them is at night, when they exit the shelter of coral or rock to hunt in the open. However, bright white dive lights tend to cause hunting eels to freeze or flee for cover, so it’s a good idea to observe them with a red light, which is less disruptive to the vision of most nocturnal animals. An eel ambush is fascinating to watch, as they are surprisingly fast and can move their bodies in unexpected ways.

Less well-known than morays, snake eels (Ophichthidae) are another family of eels found in the Turks & Caicos Islands. As the name implies, they closely resemble snakes, sometimes leading to erroneous tales of sea snakes in the Caribbean. (In fact, there are no sea snakes at all in the whole Atlantic Ocean.) These shy, unaggressive eels spend their days buried in the sand or hiding in holes. They are mostly nocturnal, although they can occasionally be seen out and about during the day. In addition to their snake-like bodies, snake eels are characterized by spotted skin patterns and tubular nostrils on their snouts (like morays). They feed on crustaceans like crabs, mantis shrimp, and even echinoderms (sea stars, brittle stars, urchins).

The size and shape of the goldspotted snake eel leads to erroneous tales of sea snakes in the Caribbean.

Four species of snake eel occur here: the sharptail snake eel (Myrichthys breviceps), goldspotted snake eel (Myrichthys ocellatus), blackspotted snake eels (Quassiremus ascensionis) and the key worm eel (Ahlia egmontis). Finding them is not easy, as they are much less common than morays and spend a good deal of time completely buried in the sand, but the experience is well worth it. Like morays, observing with a red dive light at night will maximize your chances of seeing natural behavior like hunting and burrowing.

The third family of eel found in the TCI are the conger eels (Congridae), specifically brown garden eels (Heteroconger longissimus). Garden eels are small eels that live in permanent holes in sand and congregate in large groups, with dozens to hundreds of individuals’ holes close to each other. They spend most of their time with their rear ends in the hole and their head sticking out. As they sway in the current, they resemble a field of seagrass, that, when approached, quickly pulls itself inside the sand until danger passes. Unlike morays and snake eels, garden eels are active during the day (diurnal) and eat plankton floating by in the water column, rather than actively hunting. They can be found in sandy areas and sparse seagrass.

While the trumpetfish resembles an eel in their body shape, they are not eels. They float above the seafloor at all angles between horizontal and vertical.

In addition to eels, the TCI are home to several elongated “eel-like” fishes that are not actually eels. Sand divers (Synodus intermedius) are bottom-dwelling predators up to 1.5 ft (0.46 m) that resemble lizards and often partially bury themselves in sand. They don’t move much, opting instead to wait until unwary prey wanders by and ambushing it. West Atlantic trumpetfish (Aulostomus maculatus) are another odd-looking fish that floats above the seafloor at all angles between horizontal and vertical. These yellow-brown fish grow up to 3 ft (0.9 m) and often try to disguise themselves from potential predators and prey by hanging out near soft coral fronds with a similar shape, or closely hugging herbivorous fish like a parrotfish. A third eel-like denizen of TCI is the sand tilefish (Malacanthus plumieri), growing up to 2 ft (0.6 m) in length. These light-colored fish tend to hover a few feet off the sea floor in sand or rubbly areas, building burrows that they dive into when threatened. While these three fishes share the same general body shape as eels, they differ in that they have pelvic fins and belong to different fish families.

These are just a few of the thousands of fascinating and beautiful fishes that call the Turks & Caicos Islands home. As you explore this amazing underwater world, make sure you practice good snorkel and dive etiquette to protect yourself and the ecosystem. Don’t touch or pick up any marine organism, and always inspect an area before you put your hand on it. Together we can preserve and protect our “Beautiful by Nature” Islands for generations to come.

For references or more information, contact co*****@fi**********.org.