The moray eel family (Muraenidae) is a big one, consisting of 15 genera and 200 different species found in the world’s marine environments, with only occasional recordings of these animals entering brackish or fresh water. Though consumed in some areas of the world, their flesh can be toxic and could cause illness or death. Ancient Romans used to farm Muraena helena in seaside ponds, as these moray eels were considered a delicacy. Moray eels are vital for the balance of the ecosystem - as the apex predators in their ecosystems, they keep prey species populations under control.
Fun facts about moray eels
- Young eels are called elvers.
- Giant moray eels cooperate with other large fish species to hunt.
- They have poor eyesight and rely heavily on their sense of smell
- Some have teeth that point backwards to prevent prey from escaping, and some have large molar-like teeth for crushing.
- Moray eels are the only known vertabrate that uses a second set of jaws, the pharyngeal jaws, to both restrain and transport prey.
What is a moray eel?Moray eels have compressed bodies and fused fins, giving them a snake-like appearance. These fish are quite shy and live under ledges and in rock crevices. Moray eels are long-lived and range in colour, pattern and size, measuring between 15cm and 4m. The Aquarium houses four species: the honeycomb, geometric, zebra, and tiger reef moray eels. Moray eels have a very good sense of smell and another set of jaws in the throat, which allow them to secure prey. Bites from these beauties can quickly become infected due to the bacteria in their teeth, but thankfully these animals are generally not aggressive towards humans. Moray eels do not have bony gill covers, but rather two round openings just behind their heads. They use their mouths to pump water through these openings. They secrete a protective mucus to protect their scaleless skin. In sand-dwelling morays, the mucus allows grains of sand to stick to the sides of their burrows.
Habitats and lifestylesMoray eels live in shallow water near shore areas, continental slopes, reefs and deep seabed areas. They are found in both tropical and temperate waters in marine environments. Moray eels are opportunistic feeders and eat fishes, octopuses, and crustaceans. Roving coral groupers are known to “recruit” giant moray eels to help them hunt. With their slender bodies, the moray eels can flush prey from holes and crevices that the grouper cannot access. Most fish with rounded heads create negative pressure to assist in swallowing prey. Moray eels, with their slender heads, are unable to create this negative pressure. Instead, they have a second set of jaws, known as the pharyngeal jaws. These jaws are found in the throat and equipped with sharp teeth. While feeding, moray eels propel these jaws forward into the mouth to grab, control and pull the struggling prey back into the throat and into the digestive tract.
ReproductionMoray eels have no specific mating season but mate when there is enough food and a stable habitat. Warmer water temperatures increase the chances of success. Moray eels are oviparous, meaning that eggs are laid and hatched outside the womb. Moray eel females find a safe, hidden place to deposit the eggs, releasing an odour to signal their presence to males that release sperm to fertilise the eggs. It can take 30 to 45 days for the larvae to emerge, and the temperature of the water often dictates the length of incubation. These larvae, once hatched, instinctively know how to care for themselves. After about a year of surviving as part of the plankton, the moray eel larvae are big enough to swim to the ocean floor and hide in rocks or crevices. A high percentage will have become prey for various predators. The moray eel is ready to mate around three years of age.
Animals that look like eels, but are not:
Electric eelDespite its name, the electric eel is actually a carnivorous freshwater fish, closely related to carp and catfish. These fish use an electrical charge, generated from about 6000 specialised cells called electrocytes, to stun prey and deter predators. Electric eels live in the Amazon, South America, and can grow up to 2,4 metres long.
West African lungfishNicknamed “living fossils”, the West African lungfish has been around for nearly 400 million years. Lungfish have gills to extract oxygen from water, but their unique biological adaptation of a lung allows them to breathe air, too. So, their diet ranges from frogs and fish to tree roots and seeds. West African lungfish are found throughout sub-Saharan Africa.
KingklipKingklip belongs to the cusk-eel family, a group of marine bony fish. Their bodies are elongated and their tail, dorsal and anal fins are joined into one long fin, giving them an eel-like appearance. They are bottom-dwelling fish, found at depths of 50 to 550 metres. Kingklip is a common table fish eaten in South Africa and are a green-listed species on the WWF SASSI List.