The phrase “slippery as an eel” may be far more familiar to you than the actual species. However, these fascinating creatures are an important part of the ecosystem and a popular food in many parts of the world.
You may be surprised to know there are more than 800 species of eel out there, as well as numerous fish species that are considered “honorable eels”.
Freshwater eels (known as unagi in Japan) belong to the Anguillidae family and comprise of about 19 species and 6 subspecies They have two continuous fins running along the length of their bodies and measure one to three feet in length.. Some of these actually breed in salt water, although most species never travel far from home.
Saltwater eels grow up to five feet in length and have more developed gills. They also tend to have pectoral fins. A large percentage of saltwater eels are dangerous, with many being poisonous or having some other defense mechanism that can be harmful or even fatal to humans.
One of the more famous families, members of Muraenidae are better known as moray eels, which are some of the largest and most dangerous species. They can grow from a mere five inches to thirteen feet and are mainly saltwater dwellers. There are about 200 species of moray out there.
Congers are another group which has gained notoriety, with some species reaching 10 feet long. They have large heads, scaleless bodies, and wide, toothy mouths. People often confuse morays and congers, despite them being very different in appearance (if you dare get close enough to check, that is).
To further whet your appetite, here are 20 different types of eels, including members of the four groups we’ve described above and several species which are considered eels (but are scientifically unrelated). There’s also a surprise bonus eel at the end you won’t want to miss!
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Types of Eels
1. Beach Conger
Common to the Pacific northwest, these congers grow to about four feet in length. Their diet comprises mainly of small fish and crustaceans. They prefer the shelter of coral reefs or rocky areas and are nocturnal hunters.
2. Black-Spotted Eel
Sometimes referred to as polka-dot eels or spotted spiny eels, this is actually a species of spiny eel belonging to the family Mastacembelidae. While spiny eels are generally considered a type of eel, they are actually an unrelated type of fish.
Their bodies tend to be light brown to dark tan in color with linear black spots that fade as they wrap down the sides to the underbelly. The shape of the spots range from round to oval.
They grow to about 20 inches and have a lifespan of 18 years. In some parts of the world, they find themselves on the menu, but their own preferred foods include plant matter, small fish, shrimp, and worms.
With their smaller size and less aggressive attitude, they make good aquarium pets, although don’t expect much diurnal activity from them.
3. Cutthroat Eel
These eels live all over the world in temperate to tropical waters. They measure between a mere nine inches to over five feet in length and are generally found at depths around 12,000 feet.
4. Electric Eel
One of the best-known species is actually a type of knifefish and was considered a single species until late 2019 when it was proposed to separate the electric eel into three separate species. Sadly, this South American native is highly endangered despite its popularity.
Electric eels have three specialized glands in its body which are able to create a low or high voltage current that the eel then discharges to stun prey. These charges are strong enough to paralyze a full-grown cow, and capturing one requires the eel to be provoked into discharging its glands completely before the captor can safely retrieve it.
This unwitting mascot for eels everywhere has a dark grey body with a distinctive orange throat. It must surface approximately every ten minutes to breathe, as they actually require air. They can grow up to eight feet long and may weigh as much as 45 pounds. Barring their loss of habitat, electric eels are able to live up to 15 years in the wild.
5. Fimbriated Moray
These bright yellow-green eels have black spots down its body which have inspired them to also be called dark-spotted morays or spot-face morays. They grow to about two and a half feet in length and prefer small fish and crustaceans.
Native to Indo-Pacific waters, they tend to prefer sheltered areas such as reefs, harbors, and lagoons where they can hide during the day.
6. Giant Moray
Another Indo-Pacific native, the giant moray is the largest moray species. They’re tan with large black spots which become a smaller leopard pattern as they age. They subsist mainly off of crustaceans and fish. They also tend to be poisonous if ingested by humans.
7. Gray Conger
Native to the Gulf of Mexico, this species is sometimes referred to simply as the conger eel or the Antillean conger. They tend to be about three feet in length, although specimens are known to reach just over five feet.
Their heads are very similar to that of the catfish, and their preferred diet is fin fish and small fish. As with most nocturnal eels, they prefer the shelter of reefs and rocky areas during the day. Unlike their giant kin, the gray conger is not only edible but a common site at fish markets.
8. Half-Banded Spiny Eel
Another notable imposter in this list, the half-banded spiny eel is a mere eight inches long with vertical markings that resemble bands. They’re native to the Orient and live up to 15 years.
Unlike many species on this list, these spiny eels actually prefer sandy or gravelly seabeds as well as highly vegetated areas. They make great aquarium pets when placed with larger fish.
9. Longfin African Conger
Sometimes referred to as the blackfin conger, this Indo-Pacific species has a brownish-grey body with black patches on the eye and pectoral region. There’s a bit of yellow on and below the fins, while the median fins are edged in black. They use their two rows of teeth to devour crustaceans and small fish, growing to approximately four feet in length.
Longfins are found throughout the Indian Ocean, as well as along the western Pacific. They prefer reef flats and seagrass beds, and range in depth from shallow lagoons to over 260 feet.
10. Mottled Conger
Growing up to four feet long, the mottled conger is native to the southwestern Pacific region and is often confused with similar species throughout both the Atlantic and Pacific. They’re equally capable of breathing in and out of water. The males notably dig burrows for the eggs.
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11. Ocellated Spiny Eel
Light brown to tan in color with short vertical stripes and mottling, the ocellated spiny eel has a lifespan of 18 years and grows to approximately six inches in length. Native to Africa, they’re sometimes referred to as the African spiny eel and migrate into lakes when the dry season approaches.
This family of eels are known as snake eels and consist of 62 known genera. Due to their preferred food including worms, they’re avid burrowers and thus several species lack fins.
They’re non-venomous but often bear the spotted or striped coloration of more dangerous species. Ophichthidae can be found in temperate to tropical bodies of water and sometimes migrate into rivers.
13. Peacock Eel
While these eels tend to be light brown with a yellow stripe and eye-shaped spots along the upper body, the exact coloration and markings are known to vary. They’re a hardy species that can grow up to one foot long and make popular aquarium pets due to their docile nature and 18 year lifespan.
14. Purple Spaghetti Eel
This peculiar species has a very thin body that grows up to 17 inches in length with purple or pinkish-brown coloration. Oddly enough, their heads are so small, they’re very difficult to pick out and its tiny eyes are covered in skin.
Native to the eastern Indian Ocean, they can be found in all types of water and enjoy larvae and insects in addition to the usual crustacean and small fish diet of their kin. These strange eels have a lifespan of up to 12 years.
15. Slender Giant Moray
Not to be confused with the giant moray, this species grows up to 13 feet in length, making them the longest of the morays. They have a muddy appearance with a greyish-brown dorsal fin that fades to white at the ventral area. They’re native to the western Indo-Pacific region.
16. Snowflake Moray
These Indo-Pacific morays only measure about 20 inches long and live about four years, making them a popular saltwater aquarium pet when paired with larger, aggressive fish. Despite their small size, they’re aggressive biters and live off of the usual diet of crustaceans and small fish.
They can be found up to 100 feet below the surface. Their white speckled bodies also have black spots, giving them the appearance of being dusted in snow.
17. Snyder’s Moray
Comprising of several subspecies, Snyder’s morays are the smallest of all eels, measuring a mere four inches in length. They have a reddish-brown body with tiny brown and white spots, giving it the nickname fine-spot moray. Native to the Pacific Ocean, they’re most often found in coral reefs.
18. Tire Track Eel
Named for the dark black markings on its brown body that resemble tires, this Asian species measures 3.5 feet long and is another popular aquarium species. They burrow into gravel to hide from predators during the day and have a fairly wide diet which includes worms and plant matter in addition to the usual seafood diet.
19. White-Spotted Conger
Hailing from the northwest Pacific, this diurnal species can grow up to three feet long. They can be dangerous towards humans when fully grown but are also a popular food eel in Japan. The name comes from the line of small white spots that run along each side.
20. Zebra Moray
Having similar markings to a zebra, this Indo-Pacific species has the widest range of diet among any species listed here. They’ll eat any form of meat, from crustacean and fish to shellfish and squid.
Bonus Eel: Champ, Nessie, and the Anguilla Eel Theory
One of the oldest theories about the Loch Ness monster’s true identity was that it’s some form of giant eel. As far-fetched as this theory is, there’s now some evidence to support it. Amid all of the strange theories, scientists are taking this one seriously, thanks to an extensive study in 2018 to 2019.
Fast forward to 2005 when forensics expert William McDonald provided his research for a fictional book entitled The Loch by Steve Alton. His evidence included claims of a four-inch barbed tooth found in a partially eaten deer carcass.
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McDonald cross-referenced the tooth’s shape with known creatures and found it matched an Atlantic species of eel called the European eel (Anguilla anguilla).
These eels can be found throughout Europe and the North-Eastern Atlantic and have been a popular food eel in England. This species is known to grow up to 4-1/4 feet long but normally are only about 2-1/2 feet long.
They’re born in saltwater and migrate inland where they spend most of the first 20 years feeding and growing. At 18 to 20 years, they reach sexual maturity and return to the oceans to breed. They’ve been known to live 80 years or more in captivity.
According to McDonald’s theory, an Anguilla had migrated to the Loch and become trapped when workers used dynamite to build roadways, likely collapsing an underwater entry point. The trapped eel was unable to breed and thus continued growing due to the large size of the Loch.
To match the reports of Nessie, an eel would have to reach 30 feet in length, which is unlikely but (theoretically) not impossible.
The 2019 research confirmed several species of eel live in the Loch as well as plenty of food, and there’s likely enough silt for a giant eel to hide. Unfortunately, Nessie may have died of old age by now if she was indeed a trapped Anguilla eel.
Another species of Anguilla, the American eel (Anguilla rostrata) lives in the US and is believed to be the true identity of Champ, the serpentine monster of Lake Champlain. They normally grow up to four feet and live about 15 years in the wild. They’re also the only freshwater species native to the U.S.
Sadly, the American eel is considered endangered and the European eel is critically endangered, meaning our grandchildren may never get to see either of these lake monsters if the Anguilla theory is true.