Weird shark species: Frilled shark

See the teeth and the lovely face of the frilled shark. (Photo: OpenCage/Wikimedia)

When sharks come to mind, the archetypal vision that tends to prevail is that of an antagonistic, blood-thirsty great white shark in a Hollywood film or sensational television documentary. Sadly, this kind of overgeneralization does a great disservice to the more than 470 fascinating species that currently make up this group of cartilaginous fish. While they may be apex predators with free reign at the top of the food chain, that doesn't change the fact that a quarter of all sharks and rays are currently threatened due to commercial exploitation and overfishing.
To celebrate the remarkable diversity of these animals, here are 10 of the most bizarre shark species. Some of them are downright alien-like (like the frilled shark seen in the photo above), but rest assured — all of these creatures are real and can be found in our oceans!

Frilled sharks

Weird shark species: Frilled shark

Frilled sharks are named for the slits in their gills. (Photo: Awashima Marine Park/Getty Images)

One might think that such a long-bodied fish like this must related to an eel, an oarfish or some kind of mythical sea serpent but nope, it's definitely a shark! Frilled sharks are named for their gill slits, which have a tendency to extend and "frill" out. Because they typically live at depths below 600 meters, it's rare to see them alive near the surface. The image above, taken in Awashima Marine Park, shows a 1.6-meter-long frilled shark that was found by a fisherman in the nearby bay of Numazu, Japan in 2007.

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Cookiecutter sharks

Weird shark species: Cookiecutter shark

Cookiecutter sharks bite circular chunks of flesh out of their prey. (Photo: name/Getty Images)

While these little guys might appear oddly cute and endearing in the images above, the reason these small dogfish-type sharks are called "cookiecutters" has little to do with baking holiday cookies at grandma's and a lot to do with their grotesque feeding habits. Using their wide, strong jaws, these parasites bite circular chunks of flesh out of their unlucky victims. The resulting wound is so neat and cleanly cut that it's almost as if a cookie cutter was used.

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Basking sharks

Weird shark species: Basking shark

Basking sharks jump out of the water like dolphins and whales. (Photo: Chris Gotschalk/Wikimedia)

This creature may appear terrifying, but no worries — basking sharks are slow-moving gentle giants that use their gaping mouths to passively collect and filter zooplankton and other small marine creatures. One fascinating behavior found in basking sharks is breaching, which means jumping entirely out of the water like a dolphin or a whale. While scientists aren't exactly sure why they do this, some speculate it's to dislodge parasites attached to their bodies (cue glare towards the cookiecutter sharks).

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Megamouth sharks

Weird shark species: Megamouth shark

Very few megamouth sharks have been spotted since they were initially discovered. (Photo: Toru Yamanaka/Getty Images)

There are few images of living megamouth sharks simply because only 59 specimens of this rare deepwater species have been spotted or caught since their initial discovery in 1976. One thing scientists do know about these filter feeders is that they possess luminous photopores around their jaw — a feature that is most likely used to attract plankton and other prey.

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Goblin sharks

Weird shark species: Goblin Shark

Goblin sharks are considered to be living fossils. (Photo: Dianne Bray/Museum Victoria/Wikimedia)

These rare sharks are the last living species of the Mitsukurinidae family, an ancient lineage of sharks that dates back to 125 million years ago. Because they still retain some of their family's primitive traits, they're considered to be living fossils. Like many deep-sea creatures, goblin sharks are occasionally pulled in as bycatch by deepwater fisheries, but there is still so much to learn about them (well, aside from the fact that they're excellent at inducing nightmares).

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Wobbegong sharks

Weird shark species: Wobbegong shark

Wobbegong sharks are great at camouglaging themselves on the ocean floor. (Photo: Richard Ling/Wikimedia)

This bottom-dwelling family of sharks contains 12 different species that typically live in the shallow, warm waters of the Pacific and Indian oceans. Thanks to the colorful carpet-like patterns adorning their bodies, these sharks are great at camouflaging themselves on the ocean floor. The name "wobbegong" is derived from the Australian Aboriginal word meaning "shaggy beard" — an obvious reference to the growths surrounding the shark's mouth.

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Hammerhead sharks

Weird shark species: Hammerhead shark

Hammerhead sharks are distinctive because of their heads. (Photo: Gary J. Wood/Wikimedia)

Ah, yes, the faithful hammerhead shark! Of all the "weird" sharks on this beautiful planet, this is the one that most easily comes to mind. There are several different species within this family, including the great hammerhead (above), the scalloped hammerhead and the winghead shark. Their most distinctive feature and namesake — the flat, hammer-shaped head with eyes propped up on either end — is believed to enhance their senses. Several of these species are listed as endangered or vulnerable due to overfishing and the demand for shark fin soup in countries where it is considered a delicacy.

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Sawsharks

Weird shark species: Sawshark

The sawshark shouldn't be confused with the sawfish, which is really a ray. (Photo: Getty Images)

The sawshark is known for its distinct saw-shaped snout, and it most definitely should not be confused with the sawfish (which actually happens to be a type of ray). One way to distinguish a sawfish and a sawshark is to note the position of their gill openings. A sawshark's gills are located on either lateral side of its body (like other sharks), while sawfish gills are located on its underside (like other rays).

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Angel sharks

Weird shark species: Angel shark

They look like rays, but angel sharks are definitely sharks. (Photo: Nick Long/Wikimedia)

With their flat bodies and broad, wing-like pectoral fins, it might be tempting to classify these bottom-dwelling creatures as rays based simply on their looks, but that would be a mistake for the same reason why a sawshark and a sawfish are different (explained above).

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Megaladons

Weird shark species: Megalodon

Megaladons are an ancient shark species. (Photo: Spotty11222/Wikimedia)

Sure, this ancient shark species may be extinct, but the legendary Cenzoic predator still deserves a place on this list considering it once ruled Earth's seas with its massive, fearsome jaws. Often imagined as a larger version of the great white shark, the megalodon is considered by many scientists to be the most powerful predator in vertebrate history.

Catie Leary ( @catieleary ) writes about science, travel, animals and the arts.