10 Incredible Hagfish Facts

Animals That Have Multiple Hearts: Hagfish
© Frank Fennema/Shutterstock.com

Written by Janet F. Murray

Published: September 21, 2022

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The hagfish is a peculiar and ancient fish that inhabits the murky ocean depths, but what about other intriguing hagfish facts? There are plenty of weird and unusual creatures in the ocean, but the hagfish is undoubtedly the strangest. Hagfish are eel-like creatures that have been around since prehistoric times. They are known for their slimy skin and ability to secrete a disgusting sludge when threatened. Despite their odd appearance, hagfish are fascinating creatures. Here are ten incredible hagfish facts that will amaze you!

1. The Jury’s Still Out

Hagfish, Duiker Point, Cape Peninsula.

Hagfish produce slimes 100 times thinner than human hair but far stronger and more durable than nylon.

©Peter Southwood / CC BY-SA 3.0 – Original / License

The jury’s still out on whether hagfish are vertebrates or invertebrates. However, we know with certainty that they do not have vertebrae. Some researchers feel they do not belong in the vertebrate group and are not even fish. The confusion comes in because they have some characteristics of both groups. For example, they have a skull, a bone found in vertebrates but lack jaws, fins, or scales, an invertebrate feature. So, there is much debate about whether hagfish are vertebrates or invertebrates. But one thing’s for sure: they’re fascinating creatures that deserve further study!

2. Justly Named

If hagfish mythology is believable, they can fill a five-gallon bucket with their slime in only a few minutes. When harassed, they secrete stringy proteins from glands lining their bodies. These proteins expand into a transparent, sticky substance upon contact with seawater. Not only does this slimy barrier prevent would-be predators from getting a good grip on the hagfish, but it also clogs the gills of fish that attempt to eat them.

While some creatures find Hagfish slime irresistible (like the hokku clam, which actively seeks out hagfish slime to line its burrow), most predators have good reason to steer clear of these slimy eels. And while these messy creatures are undoubtedly unique, they have rightfully earned their nickname of ‘snot-otter’ or ‘slime-eel.’

3. Multi-Purpose Slime

Who would have thought that something so slimy could be so valuable? But it’s true – hagfish slime is strong, versatile, and surprisingly helpful. For centuries, Koreans have been using hagfish slime as a delicacy in their cuisine. They also use slime to replace egg whites and chop the body up to add to their cooking.

But hagfish slime is more than just edible. Its stringy threads are super thin, 100 times thinner than a strand of hair, but in comparison to nylon, it is far more robust and durable. Scientists are investigating the possible uses of hagfish slime. For example, we could use it to produce bungee cords, bandages, airbags, and missile defense systems for the U.S. Navy.

4. All Knotted Up

Animals That Have Multiple Hearts: Hagfish

Hagfish have a skull like other vertebrates but no other bones or spinal column.

©Frank Fennema/Shutterstock.com

While the hagfish may not be the most attractive creature, it is fascinating for its unique ability to tie itself in knots. When a predator or another threat confronts them, the hagfish quickly ties its body into a three-twist knot. This seemingly simple behavior serves multiple purposes:

  • It allows the hagfish to scrape off parasites and its copious slime that might otherwise choke the creature.
  • The knotting behavior provides additional anchor points that help the hagfish to pull prey out of the sediment.
  • The knots help to keep the hagfish from being swallowed by predators.

5. Eating Habits to Serve the Ocean

Although hagfish occasionally hunt prey, they primarily feed on dying creatures or carcasses on the bottom of the ocean. They will bury themselves face-first in a corpse, boring a tunnel deep into its flesh to eat their meal from the inside out. While this might sound gruesome, it’s an essential part of the ocean ecosystem. By consuming decaying matter, hagfish help keep the seafloor clean and disease-free. In addition, their burrowing habits help to aerate the seafloor and promote the growth of new marine life.

6. Celebrating Beauty in the Ugly

U.S. Hagfish Day is an official day to celebrate the often-overlooked creatures of the sea. This particular day devoted to hagfish and other unsightly animals is celebrated every third Wednesday in October. While hagfish may not be the most attractive creatures, they play an essential role in keeping the ocean ecosystem healthy. Without hagfish, rotting carcasses and toxic bacteria would fill the ocean. In short, U.S. Hagfish Day is a day to ‘celebrate the beauty of ugly.’

7. Efficient Digestive System

Man with slimy hagfish

Hagfish tie themselves into three knots and emit oodles of slime to deter predators.

©public domain – Original / License

Hagfish are truly unique creatures. They have extremely slow metabolisms that make it possible to live off very little food. They can go up to about six or seven months without eating! Their skin is also very absorbent, meaning they can acquire nutrients by passing through water. This characteristic makes them very efficient eaters. They can obtain all the nutrients they need without consuming anything. However, this quality also means they are susceptible to environmental changes. If the water they pass through is polluted, they will absorb the pollutants into their skin and become sick. For this reason, hagfish are fabulous indicator species. If they are healthy, it’s a good sign that their environment is also wholesome.

8. Human-Like Characteristics

As we know, hagfish can absorb nutrients through their skin. This ability is not unlike the intestinal function of humans to absorb nutrients. Scientists and researchers are very enthusiastic about this correlation as it may help further research about human digestive systems.

9. As Old as Time

The hagfish is a truly remarkable animal. Swimming in the oceans for an incredible 300 million years, they are considered a primitive species. Their earliest fossils show that they have not changed anatomically in all these millennia. Hence, their structure and form seem suitable for their environment and need no evolution. This extraordinary phenomenon provides us with valuable insight into our planet’s past.

10. A Vulnerable Species

Due to overfishing and habitat loss, the hagfish is a vulnerable species in countries such as Australia, Brazil, China, Japan, and Taiwan. The hagfish is an integral part of the marine food web. However, fisherman fish hagfish for its skin, which they use to make leather and other products. As a result, the hagfish is now facing extinction. Without this remarkable creature in the sea, our oceans would be a very different place.

Next Up – More About Fish


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About the Author

I'm a freelance writer with more than eight years of content creation experience. My content writing covers diverse genres, and I have a business degree. I am also the proud author of my memoir, My Sub-Lyme Life. This work details the effects of living with undiagnosed infections like rickettsia (like Lyme). By sharing this story, I wish to give others hope and courage in overcoming their life challenges. In my downtime, I value spending time with friends and family.

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