Join me in the cold, dark, life-sustaining NE Pacific Ocean to discover the great beauty, mystery and fragility hidden there.

Wolf Eel – No Ugly Fish!

Mr. and Mrs. Wolf Eel on February 16, 2013 near Port Hardy. © 2013 Jackie Hildering

Mr. and Mrs. Wolf Eel on February 16, 2013 near Port Hardy © 2013 Jackie Hildering.

Don’t say it, please don’t say it. This is not an ugly fish. It hurts when people say this about Wolf Eels. Such is the way when there is misunderstanding and disrespect for something you love. There is no ugly in Nature – only perfection. If the features of an animal appear foreign to you, it is because it fulfils a role in Nature that is truly awe-inspiring; possibly even beyond your imaginings.

Mature male wolf-eel - about 2.2 m long. © 2008 Jackie Hildering

Mature male Wolf Eel – about 2 m long. Can be 2.4 m © 2008 Jackie Hildering.

Wolf Eels

I hope to make this point by sharing with you why the Wolf Eel  is “designed” as it is and how very wrong many of us are in our perceptions about this species. The Wolf Eel (Anarrhichthys ocellatus), which can be as long as 2.4 m, is not an eel. It is clearly also not a wolf. It is desperately misunderstood. It is not dangerous nor “mean”. The opposite is true. They are reclusive, anything but ferocious, quite sedentary and slow moving.

The upper jaw of a wolf-eel. Impenetrable to even urchin spines! © 2005 Jackie Hildering

The upper jaw of a Wolf Eel. Impenetrable to even urchin spines! © 2005 Jackie Hildering.

Yes, the mature males have very large, fleshy, ossified heads and the species has sharp teeth but this is so they can do what so few marine species can – they can feed on spiny sea urchins, snapping them effortlessly into pieces without suffering a single puncture. They also feed on other hard-shelled animals like shellfish and crabs. Even the roofs of Wolf Eels’ mouths are impenetrable with ossified, tooth-like projections.

Each wolf-eel has distinct spots around their eyes which helps recognize them as individuals. © 2012 Jackie Hildering

Each Wolf Eel has distinct spots around their eyes which helps recognize them as individuals ©2012 Jackie Hildering.

To my knowledge there has never been an attack on a diver UNLESS, and here comes the predictable thing, we choose to habituate them. Wolf Eels spend a great deal of time on the ocean bottom in dens where, as divers, we have the enormous privilege of  “visiting” the same spot and seeing the same individuals for years. It is not just their address that makes them recognizable as individuals. Each wolf-eel has a unique pattern of black spots near their eyes.

Mature male bearing the scars of battle. © 2011 Gord Jenkins.

Mature male bearing the scars of battle ©2011 Gord Jenkins.

Some divers choose to feed them, leading to the Wolf Eels associating us with food and that’s where accidents can happen and where the wild behaviour that lets animals survive, becomes compromised. It also makes them tragically easy targets for any spear diver wanting to poach them. There is no legal fishery for this species but there is a demand for them in the Asian market which is why there are also attempts to farm wolf-fish i.e. aquaculture. Not surprisingly, wolf-eels might also be defensive when accidentally caught by anglers. I found one account from 1959 where a commercial fisherman was bitten and “The teeth penetrated the hip-waders and broke the skin on both sides of the ankle.”

Juvenile wolf eel. © 2010 Jackie Hildering-

Juvenile Wolf Eel ©2010 Jackie Hildering.

The mature males do carry battle wounds supporting that they don’t just hang out in dens waiting for a snack to come by, but rather that they will occasionally duke it out with other male Wolf Eels.  They do also sometimes need to do battle for den space with a giant Pacific octopus.  This is likely another driver for the male’s having such fleshy heads – they are better able to survive the wounds inflicted by such battles. Another unique feature about this species is their eel-like body. They are the only member of their family that have this body shape. The long tail serves in locomotion, powering them forward with big, slow, s-shaped waves while being stabilized with the long dorsal and pectoral fins (see video below). Having a long tail also allows them to den-up, curling up and around in narrow spaces between rocks and . . . wait for it . . . it lets them hold onto their eggs.

Mr and Mrs Wolf-Eel tending their egg mass © 2005 Jackie Hildering-

Mated pair tending their egg mass. Note how much darker and smaller the female is © 2005 Jackie Hildering.

Wolf Eels have long-lasting pair bonds, coming together when they are around 4 years old and having their first clutch when they are around 7. In aquariums, their life expectancy is known to be at least 28 years. Both male and female juveniles are brownish orange and look even more eel-like, lacking the big head of the adults. As adults, the females are smaller and a darker brownish grey (both remarkably camouflaged for when they are in their rocky dens).

Grandpa Wolf-Eel on February 16, 2013 near Port Hardy. © 2013 Jackie Hildering

Grandpa Wolf Eel near Port Hardy ©2013 Jackie Hildering.

Mating apparently most often occurs between October and December, with the female releasing eggs after the male prods against her swollen abdomen. He then wraps around her to fertilize the 7,000 to 10,000 white to yellow eggs that she will mould into a ball shape. This mass does not need to adhere to anything because the parents will take turns wrapping their tails around the mass, holding and turning it for good aeration until the +/- 3.5 cm young hatch some 13 to 16 weeks after fertilization.

Statler the Muppet is cute and loveable. Ergo - so are wolf-eels. Case closed!!

Statler the Muppet is cute and loveable. Ergo – so are Wolf Eels. Case closed!!

The juveniles settle into the adult sedentary lifestyle between the ages of 6 months and 2 years (presumably dependent on food supply and den availability). One juvenile is even known to have travelled a minimum of 1,000 km; having been tagged in Port Hardy, BC and found back in Willapa Bay, Washington two years later. It was long thought that Wolf Eels always mate for life but, this is not always the case. The males do compete for females who will sometimes opt to swap dens and go live with the competitor. Sound like any other species you know? Wonder if it happens at mid-life? The wolf-eel is indeed akin to us in so many ways. It is a homebody that likes crunchy snacks and prefers that they come right by the front door; they are great parents and are docile unless fighting for home or partner. They invest in durable relationships and – they are only as strange looking as we terrestrial bipeds would appear to them. Range: Sub-tidal to 226 m; Baja California (Mexico) to the Aleutian Islands (Alaska); west to Russia and south to the Sea of Japan.

Female Wolf Eel guarding eggs. March 2016 @Jackie Hildering.

Female Wolf Eel guarding eggs. @2016 Jackie Hildering.


Mr. and Mrs. Wolf Eel on February 16, 2013 near Port Hardy. © 2013 Jackie Hildering

Mated pair in 2013 near Port Hardy ©2013 Jackie Hildering.

Me and a mature male wolf eel.

Me and a mature male Wolf Eel ©2012 Norris Colby.

Mature male wolf-eel. © 2007 Jackie Hildering

Mature male Wolf Eel ©2007 Jackie Hildering

Mature male wolf-eel. © 2007 Jackie Hildering

Mature male Wolf Eel ©2007 Jackie Hildering

For these and more images of the wolf-eel, please see my gallery at this link. 

Remarkable video of a mature male Wolf Eel eating a Giant Pacific Octopus by Andrew Eve.


15 Responses to “Wolf Eel – No Ugly Fish!”

  1. Chazz

    You always have something fabulously interesting and things I never knew! Thank you!

  2. Good Jacqui

    Terrific blog again Jackie! Love the humour you bring to your writings as well 🙂

  3. Paul Sim

    Nice post. Especially liked the bit about them dooking it out with an octopus – this is not something that I have ever seen but Lily and I surfaced from a dive in Barclay Sound a few minutes before our dive instructors witnessed a battle between the two and it wasn’t until you mentioned the den that I had been able to form an idea of why they would be doing that. So, a long time mystery has once again been solved by our Marine Detective! Well done Jackie.

  4. Chantal hildering

    Aunty Jackie YOU just blow my mind! Your blog on wolf eels, just changed my outlook on wolf eels 🙂 thanks for sharing your amazing talent and researching on marine life with us!!

  5. Lee

    This is funny. I am watching a show and I just had the thought that Jim Henson might have used these fish as a concept for his Muppets. Striking similarities!!

  6. Victoria Olde

    Outstanding oceanography! Thanks for the share.


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