Frilled shark

© Avax News

Heard of the Kraken? 
Well, this may be the one who started all the rumors. The frilled shark (Chlamydoselachus anguineus) is one of two sharks in the Chlamydoselachidae family, mainly found in the Atlantic and Pacific Oceans, in scattered locations. 

This primitive-looking shark has changed very little, coining the nickname "living fossil." Some refer to it as an eel or snake, but it's anything but. It's a poor swimmer, first of all, unlike the graceful eel/snake. These small animals also pack 300 smaller, razor-sharp teeth in 25 rows of teeth, with jaws ending at the end of the fish's head. 

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© Kootation

It gets its name from the frilled gills on its head (sort of looks like a mudpuppy, to be honest, and those are adorable), and gets no bigger than 2 m (6.6 ft).  It is dark brown, helping it camouflage into its preferred environment: the dark, deep ocean.  It has been caught as deep as 1,570 m (5,150 ft). 

In Suruga Bay, Japan it has been commonly found at depths of 50–200 m (160–660 ft). It has rarely been seen on the surface. In 2007, fishermen caught a species, alive, and moved it to a nearby marine park. However, it died hours afterwards.

Unlike its South African relative, C. africana, it sports more vertebrae (160–171 vs. 147) and more turns in the spiral valve intestine (35–49 vs. 26–28). It also has a longer head, shorter gill slits, and larger overall size.

It's extremely flexible jaw allows it to swallow its food whole, its teeth making it impossible to escape. It mainly prefers cephalopods, bony fishes and other sharks. It may capture its prey by lunging forward... just imagine a snake attacking. Due to its diet, it is hypothesized that these animals vertically migrate up the water column every night, taking part in one of the largest migrations in the world. No worries, though, it's highly specialized for such a trek, and for life in the deep ocean. It has a reduced, poorly calcified skeleton, and an enormous liver, which helps it maintain neutral buoyancy with little effort. It has an "open" lateral line, where the mechanoreceptive hair cells are exposed; it's one of the few sharks with this "open" line. 

Like many sharks, it probably is preyed upon by bigger sharks. Parasites also plague this shark, the most common being a tapeworm in the genus Monorygma, the fluke Otodistomum veliporum, and the nematode Mooleptus rabuka.

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© Kelvin Aitken

Not much more is known about this species, but it does practice viviparity with yolk-sac, and may have a gestation period up to three and a half years. Be glad you aren't a frilled shark, pregnant moms. Otherwise you'd be carrying that little bean around for years... literally. Their litter size varies from two to fifteen, and no breeding seasons has been determined.

They are occasionally caught as bycatch, but due to their small size have no economic value. In fact, they are rarely encountered alive, and thus pose no danger to humans... except some scientists have been known to cut themselves on their sharp teeth. The IUCN has assessed this animal as Near Threatened (NT).

did you know about this species of shark?

glossary

• Bays: A body of water connected to an ocean or lake, formed by an indentation of the shoreline.
• Bycatch: The part of a fishery’s catch that is made up of non-target species. 
• Calcified skeleton: A skeleton that has been hardened by the accumulation of calcium salts.
• Cartilaginous: A skeleton made of cartilage.
• Cephalopods: The most intelligent, mobile, and largest of all molluscs. These include: squid, octopuses, cuttlefish, the chambered nautilus, and their relatives.
• Flanks: Side of an animal.
• Gestation: The period in which a fetus develops, beginning with fertilization and ends at birth.
• IUCN: International Union for Conservation of Nature.
• Lateral line: A system of sense organs found in fish that detect movement and vibration in the surrounding water.
• Vertebrae: Any of the bones or segments composing the spinal column.
• Viviparous with yolk-sac: Also known as aplacental viviparous and previously known as ovoviviparous/ovoviviparity; it is the production of eggs that are fertilised and hatch inside the female shark but the embryos lack a placental connection to the oviduct or uterus and so do not feed off the mother.

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