The Wolf Eel (Anarrhichthys ocellatus), is a captivating creature that often gets mistaken for an eel. The name doesn’t help! But it’s actually a type of ‘wolffish’ and not an eel at all. Among its wolffish relatives, the Wolf Eel is unique because of its elongated, eel-like body. They do all have long bodies, but not as long as the wolf eel.
It is the only extant species in the genus Anarrhichthys. There are four other types of wolffish, including the Atlantic wolffish which make up the genus Anarhichas and together these make up the family Anarhichadidae.
Appearance & Characteristics of Wolf Eels
Wolf Eels can grow to be very long fish. They are known to reach lengths close to 8 feet long (up to 7ft 10 in), and up to 18.4 kg (41 lbs) in weight!. So they can grow to be longer than an adult human and about the same weight as a medium sized dog!
Adult wolf eels have gray bodies that are adorned with an attractive mix of black spots and bands, making them stand out, easily identifiable. They might also have an olive or brownish tone to their bodies, but gray is the most common. As youngsters though, their tone is a deep orange, with black spots down their posterior. They can look almost snake-like as juveniles. As they mature, the orange fades into their adult colour.
Their eyes are large and mysterious, and from some angles can look eerily familiar. They have razor sharp teeth and very strong jaws, which both play a crucial role in their diet. Like most fish, they have pectoral fins and a single dorsal fin that stretches down their body, but they don’t have any pelvic fins.
There is not much difference between the sexes, but males are usually a tad lighter, while the females flaunt a darker shade of gray.
Distribution – Location and Habitat
The Wolf Eel is found predominantly in the Northern Pacific Ocean, with little evidence of any deviation from these waters. They are fond of the chilly waters of the Bering Sea near Japan and Russia, but can also be found at the other end of their range around the coasts of northern California. They are mostly found in shallower waters, near reefs and cover, but are also known to roam as deep as around 220 meters (740 feet).
Of the fish observed, the young quite like open water, but as adults they instead appear to prefer the cozy confines of rocky hideouts, crevices, and caves in reefs. These, areas, where there is plenty cover and vegetation appear to be their favourite habitat. When pared up with a mate, the male and female will share their cave or crevice together, often for life.
The Lifestyle & Behaviour of Wolf Eels
Wolf Eels don’t like the limelight, but they are curious fish. They are rarely aggressive but they do have a painful bite due to their strong teeth and jaws.
Their unique snake-like swimming style is has a charm to it, and it’s more likely that you will see juveniles swimming about than adults. The older fish prefer to stay in their cover, waiting for prey but also protected from predators.
These fish are known to behave monogamously when they team up with a mate, and they both look after their hatch of eggs – with one always present in their home at any time.
Diet & Nutrition of Wolf Eels
Wolf Eels are well equipped for eating crustaceans and marine animals that have a hard shell. They have incredibly sharp canine teeth in the front and powerful molers toward the back of their very powerful jaw. This gives them the perfect tools for crunching up shells. They are known to eat crabs, sea urchins and sand dollars, mussels and clams. They have even been known to eat young pacific octopus.
Young wolf eels are more fond of softer, small fish and in captivity have been known to gobble up to 100 tiny fish in one go! Adult wolf eels in captivity also seem to prefer a softer meal, such as squid which is an easier meal. When given the choice between a hard or a soft meal, they will choose the soft more often than not.
Predators & Threats to Wolf Eels
Despite their size, the wolf eel does have its enemies, and there is always a bigger fish ready to pounce given the chance. As adults, they are often preyed upon by harbour seals and also many types of shark that share their waters.
As young juveniles there are more fish that will take advantage. Fish like kelp greenling and rockfish will snack on young wolf eels or more likely on wolf eel eggs, as they make for an easy snatch-and-run meal.
Wolf Eel Reproduction
As I’ve mentioned before in this post, Wolf Eels believe in lifelong, monogamous partnerships. Once they find ‘the one’, they mate for life. They may find a new partner if one of them dies or is killed, but given the chance, they will bond for life. They reach sexual maturity around the age of 7 and this is when they will find a mate.
The reproductive season lasts October until around the end of January each year. Once a mate is chose, the male will wrap himself around the female, with his head located close to the abdomen. The female swill then lay her eggs, which can be a clutch of up to 10,000 eggs. The male will then fertilize the eggs externally.
Once the eggs are all out and fertilized, the female will wrap around the eggs to form them into a spherical ball, and she will stay wrapped around the eggs to keep them safe. Once she has finished preparing the eggs and settled in place, the male will wrap around as well to add an extra layer of protection. The female will periodically massage the ball of eggs to keep water and oxygen in good supply. Then after about four months of tender care, the eggs hatch, releasing the next generation into the ocean.
Once the eggs open up, the tiny larvae, about the size of a small finger (1.6 inches or 40 mm), drift along with the ocean currents. They munch on little creatures like copepods and other tiny sea drifters. After a while, they start swimming freely in the deeper parts of the ocean.
As these young wolf-eels grow up, they start exploring closer to the shore, searching the ocean floor for yummy treats. When they find a special partner and a cozy spot in a rocky reef, they make it their home, usually staying there for the rest of their days. And thus the cycle starts again.
Lifespan of Wolf Eel
There are many stages to the life of a wolf eel. Starting out as an egg, then larvae, to their orange juvenile form and finally their greyish or brownish mature, adult form. Across all stages, they are capable of living up to 20 years in the wild, potentially a little longer in captivity.
Population and Conservation
Wolf Eel populations are believed to be stable. They are not the target of any industrial scale or commercial fishing and so there isn’t a human demand for them for food. They do sometimes appear in the nets or traps of fishermen but generally not intentionally.
Stable populations can be maintained by ensuring their rocky, cave and reef habitats are kept healthy and in good condition. A task that may yet prove difficult with the ever changing climate challenges ahead.
At present however, they are secure, populations stable and as such they have an IUCN status of ‘Least Concern’.
5 Fun Wolf Eel Facts for Kids
- Wolf Eels are not real eels; they’re actually a type of wolffish!
- When they’re young, they have a bright orange colour.
- Their back teeth are so strong they can crush hard shells like they’re potato chips.
- A female Wolf Eel can lay up to a staggering 10,000 eggs at once.
- They love playing hide-and-seek in rocky underwater hideouts.