Frilled Shark Facts - A Strange and Fascinating Fish of the Deep

A preserved frilled shark
A preserved frilled shark | Source

A Strange Fish of the Deep Ocean

The frilled shark is a fascinating and very strange fish that looks more like an eel than a shark. It has a wide head with a huge mouth and a long, slender body. Frilled sharks are sometimes called “living fossils” because they’re thought to be very similar to a prehistoric ancestor which lived eighty million years ago.

The mouth of the frilled shark is located at the end of the body instead of behind the tip of the snout as in most other sharks. The first pair of gill slits are especially long, extending from the sides of the body to underneath the throat. The gills have frilly structures on their edges, giving the shark its name.

Frilled sharks spend most of their time in deep water close to the sea bottom. Some people suggest that this shark is the basis of the sea serpent legends. It has the right shape to be mistaken for a sea serpent but it isn’t long enough, since it reaches a maximum length of only just under two meters (about six and a half feet).

Two living species of frilled sharks have been discovered. We know more about Chlamydoselachus anguineus, known simply as the “frilled shark”, than about the African frilled shark, Chlamydoselachus africana. Even so, there are lots of unanswered questions about the lives of these fish.

Video of a Sick or Injured Frilled Shark

The frilled shark is also known as the frill shark and the lizard shark. Its species name - anguineus - means "snake-like" in Latin.

Strange Features of the Frilled Shark

Mouth and Teeth

The frilled shark has a big, wide and flattened head dominated by a large mouth. The snout is rounded and the mouth has many rows of needle sharp teeth, each having three points. There are 300 teeth, which are arranged in 25 rows and point backwards.

Gill Slits

The first gill slits are so long that they give the impression that the fish has been cut on its sides. The slits are often flared and the frills on the gills are red, increasing the impression of an injury. The frills sometimes look like a collar around the shark. There are six pairs of gill slits, unlike the five pairs found in most other sharks.

Body and Fins

The shark's elongated body is brown or grey. As in other sharks, the skin is rough and covered with small teeth-like structures called denticles. The small pectoral fins are located on the sides of the shark not far from its mouth, but the dorsal (back), pelvic, anal and caudal (tail) fins are situated way back towards the rear of the body. There is only one dorsal fin, unlike the case in other sharks. The caudal fin is long and is sometimes said to resemble the wings (or "flights") on darts.

Shark Fins

Fins and external body structure of a typical shark; frilled sharks have the same fins, but their body structure is very different
Fins and external body structure of a typical shark; frilled sharks have the same fins, but their body structure is very different | Source
A drawing of a frilled shark; the shark has only one dorsal fin and has a different body shape from other sharks
A drawing of a frilled shark; the shark has only one dorsal fin and has a different body shape from other sharks | Source

The Lateral Line

Many fish have a lateral line on each side of their body. The lateral line is a row of sense organs. It contains hair cells that are stimulated by movements and low-frequency vibrations in the water. The hair cells are said to be "mechanoreceptive" because they are sensitive to mechanical pressure.

The hair cells of a frilled shark's lateral line are located in a groove that is open to the ocean. This is an unusual feature in the world of sharks. In other sharks the lateral line is embedded in the skin and is connected to the outside world through pores.

A Swimming Frilled Shark

More Unusual Body Features of the Frilled Shark

  • Unlike most sharks, frilled sharks have no nictitating membrane to cover their eyes. The nictitating membrane is a thin but tough membrane that acts like an eyelid and moves horizontally over the eye. A shark uses its nictitating membranes to protect its eyes during potentially dangerous situations, such as when lunging for a prey.
  • There are a pair of thickened skin folds traveling along the shark's belly. The function of these folds is unknown. It's been suggested that they accommodate the expansion of the digestive tract after the ingestion of large prey.
  • The huge liver contains a large quantity of low density oils and hydrocarbons (substances containing only hydrogen and carbon atoms), which help the shark to maintain its position in the water.
  • The skeleton of the frilled shark is low in calcium, perhaps because the deep water in which it lives is poor in nutrients.

The teeth of a frilled shark
The teeth of a frilled shark | Source

Unfortunately, the frilled shark is rarely seen alive. It's most often observed when it has been trapped in a fishing net and brought to the surface of the water after its death.

Lives of Frilled Sharks

Habitat

The frilled shark has a wide range in both the Pacific and the Atlantic Oceans, but it's found in only scattered patches in these areas. It may live in water as deep as 1000 to 1500 meters, but it's usually located at depths of between 500 and 1000 meters. In some Japanese waters frilled sharks have been found in water between 50 and 200 meters deep.

Diet

By analyzing the stomach contents of captured frilled sharks, scientists have discovered that they eat squid, cuttlefish, octopuses, fish and other sharks. Their feeding techniques are unknown, however. The frilled shark can open its mouth very wide and is said to be able to swallow prey that is half its size. One puzzle that needs to be answered is how the apparently slow moving shark can catch fast moving squid as well as slow moving ones. The long, thin shape of the fish may enable it to hunt in crevices and caves.

Scientists suspect that the shark generally strikes at its prey. It may draw smaller or weaker prey into its mouth by closing its gill slits and creating a partial vacuum that sucks up the animals. Though the mouth is huge, the structure of the jaws suggests that frilled sharks can't bite as hard as other sharks.

The claspers of a male spinner shark
The claspers of a male spinner shark | Source

Reproduction

Sharks have internal fertilization. The male inserts sperm into the female with his claspers, which are located under his body by his pelvic fins.

The frilled shark is said to have an "ovoviviparous" method of reproduction, like many other sharks. The eggs are retained in the female's body instead of being laid. The embryos feed on the egg yolk inside the eggs. The eggs hatch inside the female's body and the pups are born live. Around six pups are born on average, although the number ranges from two to fifteen.

The frilled shark is believed to have a slow metabolism, since it lives mainly in cold, deep water. The development of the pups inside their mother is also slow. It's thought that a three and a half year gestation period may be needed, which would be the longest of any vertebrate. In Japanese waters, and perhaps in other areas too, frilled sharks breed at any time of the year. However, the long gestation period means that the shark has a low reproduction rate.

The mouth of a frilled shark
The mouth of a frilled shark | Source

Conservation Status

The frilled shark is classified as Near Threatened in the Red List of the IUCN (International Union For Conservation of Nature). This list categorizes animals according to their nearness to extinction. Since so little is known about the shark and its population, it may deserve to be classified in a more serious or less serious category than the Near Threatened one. The evidence suggests that it may be in trouble.

Unfortunately, current deepwater fishing techniques mean that frilled sharks are being caught as bycatch along with target species. This is worrying due to the long gestation period and small litter size of frilled sharks.

The gill slits on the underside of a preserved frilled shark
The gill slits on the underside of a preserved frilled shark | Source

Frilled Sharks in Captivity

The first video in this article shows a female frilled shark that was found swimming at the water's surface in Japan in 2007. She may have been ill or injured when she was found. She was taken to a marine park and unfortunately died a few hours later. This may have been due to a prior illness, to the relatively warm water in the marine park or to a combination of these factors. Frilled sharks don't live long in captivity and therefore can't be protected or studied in aquariums or parks.

Scientists have been able to study dead frilled sharks but would love to know more about the lives of the living sharks. The fish don't seem to be dangerous to humans, unless someone gets cut by the sharp teeth while handling a dead animal. It would be a great shame to lose these creatures from the Earth, especially before we know much about them.

© 2012 Linda Crampton

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Comments 32 comments

A.A. Zavala profile image

A.A. Zavala 4 years ago from Texas

Awesome! I've been fascinated by obscure sharks, including the goblin shark. Very cool!


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Augustine. Thanks for the comment. I find the lesser known sharks very interesting as well. There are so many fascinating creatures in this world!


MrEction 4 years ago

seems to resemble, in shape, a violet goby


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Yes, MrEction, I agree - the frilled shark does somewhat resemble the violet goby in shape! Thanks for the comment.


kashmir56 profile image

kashmir56 4 years ago from Massachusetts

Hi Alicia, all great and fascinating information about there sharks,a lot of it i did not know before.

Vote up and more !!!


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you so much, Tom. I appreciate your visits and comments very much.


prasetio30 profile image

prasetio30 4 years ago from malang-indonesia

Wow....this was awesome. I had never know about this shark. Thanks for writing and share with us. I learn much from you. Good job and rated up!

Prasetio


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Prasetio. The frilled shark isn't well known, but I think it's a very interesting animal. Thank you very much for the comment and the rating.


CMHypno profile image

CMHypno 4 years ago from Other Side of the Sun

You always find the most unusual creatures to write about Alicia. Thanks for all this great information on frilled sharks - I just hope that they don't get wiped out by our modern fishing techniques


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, CMHypno. Thanks for the visit. I hope that frilled sharks don't disappear as well. If their gestation period really is as long as researchers suspect, our deep water fishing techniques could have serious consequences for the sharks.


drbj profile image

drbj 4 years ago from south Florida

Thanks, Alicia, for this interesting hub about the frilled shark - a very fascinating and little known creature that looks more like a giant moray eel than a shark. What a long gestation period you mention - 3 1/2 years! That's a very long pregnancy. Certainly long enough to discourage the females from having many more baby frilled sharks.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, drbj. Yes, if the suspicion of the researchers is correct, frilled sharks do have an amazingly long gestation period! Thanks for the comment.


b. Malin profile image

b. Malin 4 years ago

Wonderful, Fascinating Hub Alicia on "Frilled Sharks". I have to tell you I respect Sharks and I FEAR them. Last week we were on a Fishing pier in Juno, and one of the Fishermen was telling us that there were a lot of Sharks just past the pier, that people are unaware of...CREEPY.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, b. Malin. Although I'm interested in sharks I certainly wouldn't want to be anywhere near them in the water. It does sound scary to hear about hidden sharks that people aren't aware of! Thanks for the visit and the comment.


Nell Rose profile image

Nell Rose 4 years ago from England

Hi, I remember reading about this when it first came out, I think its so prehistoric looking, which is exactly what it is, it's a scary looking thing, I wouldn't be frilled to meet it! lol! really interesting, voted up!


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Nell. Thank you very much for commenting and for the vote. I agree - the frilled shark does have a prehistoric look about it! It's a fascinating fish.


PDXKaraokeGuy profile image

PDXKaraokeGuy 4 years ago from Portland, Oregon

wow, what a terrific creature! It looks like it's smiling and happy... and those girls are sure something! UP and shared


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you very much for the vote and the share, PDXKaraokeGuy! I agree - frilled sharks are terrific creatures. I haven't noticed before, but the shark does almost look like it's smiling (in human terms) when its mouth is open!


MartieCoetser profile image

MartieCoetser 4 years ago from South Africa

What an extremely interesting hub about the Frilled Shark. Absolutely amazing and awesome. Voted up to the stars :)


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you so much for the lovely comment and the vote, Martie! I appreciate them both very much.


Wesman Todd Shaw profile image

Wesman Todd Shaw 4 years ago from Kaufman, Texas

I'd never heard of this fish! He's frilled by I'm thrilled!

The plight of the sharks is becoming pretty intense, isn't it?

They're regarded like wolves these days, and like the wolves - it's going to take some big government effort to keep the sharks around.

People are forever killing predators - I hate it.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Wesman. Yes, the way that sharks are being treated is very worrying. There seems to be little respect for them in many areas, as in the case of the millions of sharks each year that have their fins cut off for shark fin soup and are then thrown back in the water to slowly die. It's a horrible situation.


Karanda profile image

Karanda 4 years ago from Australia

Fascinating Alicia. I'd never heard of a frill shark, much less seen a photo or video of one. It certainly would be a shame for these prehistoric looking creatures to become extinct. We can only hope someone is working to keep them out of the fishing nets.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Karanda. Thank you for commenting. It would be a great shame if the frilled shark became extinct. Like you, I hope that deep sea fishing techniques improve so that frilled sharks aren't caught as bycatch.


Kyah Sullie 4 years ago

I was looking for something fascinating to do a project to do on and choice this one and you helped a lot.


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Hi, Kyah. The frilled shark is certainly fascinating! Good luck with your project.


huga shimmy 4 years ago

your website is ok


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thank you, huga shimmy, but this isn't my website!


jhon horkinmyer 24 months ago

the frilled shark is awesome! this website totally helped me get an A+ on my report! #


AliciaC profile image

AliciaC 24 months ago from British Columbia, Canada Author

Thank you, jhon. I'm glad you found the article helpful. Congratulations on the A+!


Dan 7 months ago

Awesome! THIS WEBSITE HELPED OUT ALOT


AliciaC profile image

AliciaC 7 months ago from British Columbia, Canada Author

Thank you very much for the comment, Dan.

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