Wildlife of the Week!

© Alexa Desautels. A wolf-eel is spotted emerging from its den at the Shaw Centre for the Salish Sea.

This Wildlife of the Week we bring you a beautiful and lively creature of the Salish Sea! This creature is commonly mistaken as an eel, as per its namesake. Who can spot the creature in the image? Hint: Look in the lower half of the image at the creature swimming out of the rocks. The wolf-eel (Anarrhichthys ocellatus) is a stunning animal of the Pacific, but a misnomer too. The wolf-eel is actually a fish, and has a fascinating story to match. Read along below to learn more!

The wolf-eel is one species within a group of five that are known as “wolffish”. A wolf-eel is often spotted dwelling within caverns, rocks and small caves, but when it does emerge its impressive size becomes apparent. The wolf-eel may reach lengths of just over eight feet long! This equates to a weight of about 40 pounds. The animal has a wrinkled, thick, muscular head and jaw region which tapers to a muscular and skinny tail. They have paddle-like pectoral fins, a long dorsal fin and a mouth full of small, pointed teeth. The body color is usually blue to grey, sometimes greenish, with circular spots throughout. A bright brick or orange color is seen when the animal is young, however. 

The reason for their “eel-like” name is due to their body form, and not any evolutionary relationship to eels themselves. 

The wolf-eel is a Pacific species, ranging from Kodiak, Alaska to northern Baja California. It can also be found west to Russia and south to the Sea of Japan. The fish is often found within reefs and the subtidal zone in chosen dens, or near pilings and other dark rocky shelters. It is more rare to see a wolf-eel come completely out of its den, as they are often tucked and folded within their home with only their head peering out. Fascinatingly enough, the wolf-eel has been found as deep at 740 feet! They are loyal to their den, unless it is claimed by a larger wolf-eel or an octopus , who looks for the same homes as the wolf-eel. The wolf-eel is a true homebody, and once they find their mate, they will usually settle and remain in these dens (so long as they are not forced out) for the rest of their lives. 

The wolf-eel is a carnivorous predator with a strong jaw for hunting prey. The wolf-eel will hunt fish as well as a variety of invertebrates such as clams, crabs, sand dollars, sea urchins and snails, to name a few. To feed on many of these invertebrates, the above-mentioned jaw is able to crush shells efficiently. When you see a wolf-eel with its head out of its dwelling, it might be looking for passing prey! 

The wolf-eel has a very interesting life history. They spend their time as young larval zooplankton in open waters before moving to shallow areas. The species mates for life and is ready to find a mate between 4-7 years old. Both parents cooperate to guard and take care of their eggs. Once the pair has selected a home, the female will lay her eggs, which may number up to 10,000! The parents will alternate leaving the home to feed, and will protect the eggs for 3-4 months until they are ready to hatch. The wolf-eel guards the eggs vigilantly, and will even wrap its body around the mass to keep it safe. This is usually seen with the female wrapping her body around the egg mass, and the male following to wrap around her, forming complete protection. The female will also circulate water over the eggs. 

Males and females can be told apart by the larger, more bulbous head/forehead of the male fish. Females also tend to have brown coloration, whereas males are often greyish. 

The wolf-eel is a truly unique member of the Salish Sea community, and others. Despite their name and size, they generally move slowly or not at all. They appear to move like a snake, and appear quite graceful. They are also rarely aggressive to others that are not wolf-eels. With divers, the wolf-eel is generally shy or even friendly and curious. You should always respect a wolf-eel’s space if you come across one when diving, and not seek out an interaction (as with other wildlife). 

The wolf-eel must stay vigilant for predators such as Harbor seals. Other fish can also prey on their eggs. In terms of conservation risk, the wolf-eel is not currently threatened, but there are steps to take/maintain in order to keep the population stable. Wolf-eels can be caught as fishing bycatch, such as in crab traps. They are also susceptible to pollutants from storm and sewer drains, and other forms of human pollution. They require a suitable rocky habitat to survive. It is believed that wolf-eels have a long lifespan. 

What a remarkable fish! There is much more to learn about the wolf-eel still- try your luck with some trivia below!

  1. True or False? The wolf-eel adult has molars on its top jaw to aid in crushing prey. (ANS: True). 
  2. The wolf-eel has a large appetite. (ANS: True). 
  3. The wolf-eel has a lateral line. (ANS: False. Though some fish do, the wolf-eel does not). 

BONUS CHALLENGE: 

What is a major reason that the wolf-eel is grouped with fish and not eels?

They have pectoral fins behind their heads, a fish characteristic. 

Article Authored By: Alexa D., B.Sc./ Five Star Whale Watching. 

To learn more about this fish, visit our References below!

Mayne Island Conservancy.

Wolf-eel | Animals | Monterey Bay Aquarium

Wolf Eel | Seattle Aquarium

Wolf eel | Washington Department of Fish & Wildlife