The Hagfish: A Strange Animal That Makes a Useful Slime

Updated on July 20, 2018
AliciaC profile image

Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about animals and plants.

The head of a hagfish protruding from a sponge
The head of a hagfish protruding from a sponge | Source

A Strange Creature

The hagfish is a strange sea creature with a very elongated body. It looks something like an eel but belongs to a different group of animals. Hagfish are jawless and are known for the large amount of slime that they produce. They are also famous for feeding on dead and dying animals—often from the inside of these creatures—and scraping the flesh off with their teeth, which are located on a movable cartilaginous plate.

Hagfish have one feature that is potentially very useful for humans. Their skin makes a sticky and protective slime that is made of mucus and strong threads of protein. Researchers hope to use the protein threads to make a fabric. In certain circumstances, the intact slime might be useful in protecting humans. One species is used for other reasons and is harvested in large numbers. People in some countries like to eat the flesh of this animal. The skin is used to make a product that resembles leather and the slime is used in place of egg white in recipes.

A hagfish in a lab
A hagfish in a lab | Source

A Living Fossil

Based on the fossil evidence, the appearance of hagfish hasn't changed significantly for 300 million years. The animals are sometimes called "living fossils". They have a partial skull, which is made of cartilage, but they have no vertebrae. They have a rod known as a notochord instead of a bony spine. The notochord is made of a material resembling cartilage.

Hagfish are not invertebrates and are technically not fish either. They are classified in the phylum Chordata, as fish and humans are, but are placed in their own class (the Myxini). The members of the phylum Chordata have a notochord at some stage in their life cycle. In us, the notochord has been replaced by bony vertebrae by our early childhood years. In hagfish, it stays in place throughout the animal's life.

There's been considerable debate about the origin of hagfish. One theory says their ancestors were vertebrates (chordates which develop backbones made of vertebrae). The modern animal is said to be a form that degenerated and lost its ability to make vertebrae. The second theory says that the evolutionary line containing hagfish never developed the ability to produce vertebrae. The first theory is more popular among scientists today.

Hagfish are sometimes known as slime eels due to their shape and their production of copious amounts of slime. This name is not biologically appropriate, though, because eels are true fish and hagfish aren't.

The Body of a Hagfish

External Appearance

Hagfish are generally pink, blue-grey, dark brown, or black in colour. They have three or four pairs of tentacle-like structures around their mouths and nostril. These tentacles are called barbels. They also have a white patch of skin where each eye is located.

The slime glands of a hagfish are visible as a row of white spots on each side of the body. The animals have no scales and have a skeleton made of cartilage. Unlike fish, they have no dorsal fin on their back and no paired fins. They do have a tail or caudal fin, however, which extends along the top and bottom of the animal for a short distance. The end of the body is flattened and looks like a paddle. The animal's skin is loosely attached to its body.

Sense Organs

The eye has no lens and no muscles, but it does have a simple retina containing light receptors. Hagfish can distinguish light from dark but can't see an image. They have an excellent sense of smell and a good sense of touch to compensate for their poor vision. They have a single nostril, which is located above their mouth and carries chemicals to the olfactory organ. The barbels contain touch receptors and may play a role in taste sensation as well. The animal hears via two inner ears.

Maximum and Minimum Length

The Pacific hagfish (Eptatretus stoutii) lives in the eastern Pacific Ocean, which is my part of the world. An adult has an average length of about twenty inches. Some species are much longer and some are much shorter.

The goliath hagfish (Eptatretus goliath) is known from only one specimen discovered off the coast of New Zealand in 2006. The animal was a female and had a length of 4.2 feet. This is the longest hagfish known so far. On the other hand, the dwarf hagfish (Myxine pequenoi) seems to be about 7 inches in length. Its size is based on the two specimens discovered so far, which were obtained off the coast of Chile.

Highlights of Internal Anatomy

  • Hagfish are said to have four hearts—one main one and three accessory ones. The main heart is known as the branchial heart. The animal also has two pouches that act as a cardinal heart, a single pouch for a portal heart, and two pouches that act as a caudal heart.
  • The circulatory system is said to be semi-open. In some parts of the body blood flows through blood vessels, but in other parts it flows through spaces called sinuses.
  • The animals breathe by means of gills. Water enters a hagfish's body through the nostril and travels through the nasal canal to the olfactory organ. It then passes through the nasopharyngeal duct to the gills, which are located in pouches. The gills absorb oxygen from the water and release carbon dioxide into it. After flowing over the gills, the water travels back to the ocean via one or more pores.
  • Hagfish have a digestive tract, which contains a gut but no stomach.
  • They also have a brain and nerves as well as a kidney for excretion. Both the brain and the kidney are considerably simpler than ours.

A Pacific hagfish trying to hide under a rock
A Pacific hagfish trying to hide under a rock | Source

Diet and Feeding Method

Hagfish live in burrows on the muddy sea floor, generally in deep water. Despite their reputation for invading and eating the bodies of larger animals, hagfish eat mainly polychaete worms (relatives of earthworms) and other invertebrates found on the ocean bottom. They are predators as well as scavengers and have been observed entering burrows to catch fish. They are said to be able to go for months without food. Researchers have discovered that they can absorb some nutrients through their skin.

A hagfish feeds by a rasping motion, using teeth located on a plate of cartilage known as the dental plate. There are two rows of teeth on each side side of the plate. The teeth are made of keratin, a tough protein found in hooves, horns, nails, hair, and the outer layer of our skin. The dental plate acts like a rasping tongue and is both protractable and retractable.

Hagfish are often considered a nuisance by fisherman. When the fishermen haul in their catch they may find that the catch is only skin and bone and has hagfish inside.

Slime and Protective Behaviour

The slime of a hagfish is an excellent tool for defence. Immediately after being touched by a potential predator, a hagfish releases a large amount of slime. The material expands and forms thick, viscous sheets and strands when it mixes with sea water. It repels predators and can block the mouth and gills of predatory fish, suffocating them. If the slime of a hagfish enters its own nostril, the animal sneezes to get rid of it.

The hagfish exhibits another useful behavior to defend itself against attackers. If a person or a predator picks up a hagfish and the animal can't escape, it twists its body into a knot. The knot begins at the head and progresses towards the tail. The knotting process helps to remove the slime off the surface of the animal's body, which is thought to repel the predator. The knotting process may also be useful at other times when a hagfish needs to remove an old slime layer from its skin. In addition, it may provide leverage when the animal is feeding, enabling the teeth to remove food from the prey more successfully.

When threatened or disturbed, (hagfish) spew out slime at the stunning rate of four cups in a fraction of a second.

— Christine Dell'Amore, National Geographic

Reproduction

Not much is known about hagfish reproduction. The animal appears to start its life as a hermaphrodite, which means that it has both male and female reproductive organs. When it matures, one of the organs functions and the other doesn't. Research suggests that at least some hagfish can change gender during their lives.

It's thought that hagfish have external fertilization, although this isn't known for certain. Females lay eggs with a tough covering. The eggs have hooked filaments on each end which help them to become attached to objects. There is no larval stage. The eggs hatch into miniature adults.

Human Use of Hagfish Slime

People who encounter hagfish often consider the slime to be the most unappealing aspect of the animal. However, scientists see great potential in the material. They hope to use the protein threads in the slime to make a strong fabric. Some Canadian researchers have already harvested slime from hagfish, mixed the slime with water, and then spun the stretched fibers like silk.

Researchers have found that the protein threads in the slime of the Atlantic hagfish are 100 times thinner than a human hair and ten times as strong as nylon. They also have the advantage of being made by a "green" process, as opposed to fibres made from petroleum.

The strength and expansive ability of the slime is very interesting to researchers. According to a navy scientist exploring the material, it can expand to a volume that is nearly 10,000 greater than its original one once it enters water.

Though the protein threads on their own could be useful for us, the slime as a whole might provide us with protection in specific situations. Researchers are investigating the possibilities.

E. coli is used to make components of hagfish slime.
E. coli is used to make components of hagfish slime. | Source

Genetic Engineering in Bacteria

Scientists don't plan to hunt or farm hagfish. Instead, they hope to genetically engineer bacteria to make the animal's slime. Some bacteria have proved to be very useful in making substances for humans once they have had the correct gene or genes added to them. Preliminary experiments in using hagfish genes in bacteria have already been successful.

In 2017, U.S. Navy scientists announced that they had isolated the genes that make two important proteins in the slime. They inserted the genes into two groups of Escherichia coli (or E. coli) bacteria. The genes became activate in the bacterial cells and the bacteria made the proteins. The scientists were able to confirm that these were in fact the same proteins made by the hagfish.

Scientists in Singapore reported similar results with engineered E. coli in 2015. The discoveries could be very significant. Hagfish slime is believed to consist mainly of mucus mixed with filaments of the proteins produced by E. coli.

In July, 2017, a truck in Oregon carrying thousands of hagfish dropped its load on a road. The stressed animals created a huge mass of slime, as can be seen below. The animals were going to be shipped to Korea as a food source.

Other Uses of the Animals

The inshore hagfish of the northwest Pacific Ocean (Eptatretus burgeri) lives in much shallower water than its relatives. Its flesh is used as food in Korea. The skin of the animal is known as eel skin and is used to make items such as belts, accessories, and clothing.

Strange or unpleasant as it may sound, the slime of the inshore hagfish is sometimes used as a substitute for egg white in recipes. The slime is said to be obtained by banging a stick on a tank containing a living animal.

This hagfish is used so intensively that its population is decreasing and the IUCN (International Union for Conservation of Nature) classifies it as "Near Threatened".

Would you be willing to touch a hagfish?

See results

Successful Creatures

Hagfish are sometimes considered to be primitive creatures, but their slime has enabled them to be very successful animals. They have existed almost unchanged for millions of years. Their habits may seem disgusting to us, but they are very helpful for the animals and have been a wonderful survival mechanism.

Most hagfish live in deep water and are hard to study in their natural environment. There is still a lot to be learned about these fascinating creatures and their very successful lives. The effort to discover more about them should be very worthwhile.

References

Hagfish facts from the Smithsonian Magazine

Pacific hagfish information from the Aquarium of the Pacific

Reasons why hagfish are amazing from National Geographic

Useful slime from the Smithsonian Magazine

Eptatretus burgeri status from the IUCN

Questions & Answers

    © 2012 Linda Crampton

    Comments

      0 of 8192 characters used
      Post Comment

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        You've raised a good point, Sasha - a "hag gown" doesn't sound very appealing! A new name would definitely have to chosen for any fabric made from hagfish slime! Thanks for the comment and the votes.

      • Mama Kim 8 profile image

        Sasha Kim 

        5 years ago

        How fascinating ^_^ Thanks for the great read. I wonder if they made a fabric out of hagfish... would they disguise the name? I don't think designers would flaunt "hag gowns" ^_^ voting up and interesting!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thank you very much for the comment, Peggy. I appreciate the vote and the tweet!

      • Peggy W profile image

        Peggy Woods 

        5 years ago from Houston, Texas

        This is fascinating Alicia. Hagfish are useful as scavengers from watching that one video where they were feeding off of a deceased whale body on the ocean floor. I had never even heard of a hagfish prior to reading this. Thanks for writing such an informative hub! Up votes and tweeting.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thank you for the comment, macteacher. I enjoy learning about new creatures too! There is so much that is unknown about ocean life, especially life in the deep sea habitat. It's a fascinating area to explore.

      • profile image

        macteacher 

        5 years ago

        I love learning about new creatures, and this one is fascinating. It looks a little disgusting, but I'm sure to marine life - us humans look a little disgusting. It's amazing, with all of our technology, how little we know about deep sea creatures. Thanks for a fascinating hub about an unusual animal.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thank you for the comment, unknown spy. Yes, the hagfish does look somewhat like a snake. It has an unusual appearance!

      • unknown spy profile image

        Not Found 

        5 years ago from Neverland - where children never grow up.

        scary..looks like a snake. great hub about this strange animal.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thanks for the visit, Dianna. I agree - the hagfish does have a purpose and is an important part of its ecosystem. It will be interesting to see whether thread and fabric made from hagfish slime are eventually sold commercially !

      • teaches12345 profile image

        Dianna Mendez 

        5 years ago

        I wouldn't want to touch one - unless necessary. It does have its purpose in life as it contributes to the animal kingdom. Interesting that it is being considered as threads for fabric. Enjoyed the read.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thank you for the visit and the comment, Deb! I'm glad that hagfish have survived, too. They are fascinating animals, and their slime is very interesting.

      • aviannovice profile image

        Deb Hirt 

        5 years ago from Stillwater, OK

        I'm glad that they have been able to survive for so long. So many animals are nearly extinct. Thanks for the fantastic info, Alicia!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thank you very much for the comment and the votes, Seeker7! Yes, the hagfish has been very successful, even though it doesn't have the characteristics of more advanced animals. It's an interesting creature!

      • Seeker7 profile image

        Helen Murphy Howell 

        5 years ago from Fife, Scotland

        What a fascinating article. I had heard of hagfish from TV documentaries but I didn't know the half - especially about how useful their slime might be! Also the 'goliath' hagfish - that's huge compared to what I thought their size might have been! I guess they are seen as being primative, but then, if an animal is so successful with what they have, why change?

        I really enjoyed this fascinating hub - voted up awesome!!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thank you very much, drbj! I appreciate your great comment. I wouldn't mind touching a hagfish, but I'd have to prepare myself mentally before doing this!

      • drbj profile image

        drbj and sherry 

        5 years ago from south Florida

        I've never touched a hagfish, Alicia,

        In fact I seldom SEE one.

        But I can tell you this, m'luv,

        I would rather touch than BE one.

        Fascinating, awesome and outstanding in amount of information and relevant photos and videos. Thank you and an Up to you.

      working

      This website uses cookies

      As a user in the EEA, your approval is needed on a few things. To provide a better website experience, owlcation.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

      For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://owlcation.com/privacy-policy#gdpr

      Show Details
      Necessary
      HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
      LoginThis is necessary to sign in to the HubPages Service.
      Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
      AkismetThis is used to detect comment spam. (Privacy Policy)
      HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
      HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
      Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
      CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
      Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
      Features
      Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
      Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
      Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
      Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
      Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
      VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
      PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
      Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
      MavenThis supports the Maven widget and search functionality. (Privacy Policy)
      Marketing
      Google AdSenseThis is an ad network. (Privacy Policy)
      Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
      Index ExchangeThis is an ad network. (Privacy Policy)
      SovrnThis is an ad network. (Privacy Policy)
      Facebook AdsThis is an ad network. (Privacy Policy)
      Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
      AppNexusThis is an ad network. (Privacy Policy)
      OpenxThis is an ad network. (Privacy Policy)
      Rubicon ProjectThis is an ad network. (Privacy Policy)
      TripleLiftThis is an ad network. (Privacy Policy)
      Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
      Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
      Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
      Statistics
      Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
      ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
      Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)