'Sharks of the Bermuda Triangle': What is the cookiecutter shark which leaves cookie-sized wounds on victims?
National Geographic's Sharkfest is an eye-opening journey into one of the most dangerous predators of the ocean. If what you know about sharks comes from the Steven Spielberg movie 'Jaws', Sharkfest will let you learn that sharks are misunderstood creatures and are very important for the ecology. Of course, they are still dangerous and as we learn in the latest special, 'Sharks of the Bermuda Triangle', some species can be creepy.
In 'Sharks of the Bermuda Triangle', marine biologist and CEO of not-for-profit Beneath the Waves, Dr Austin Gallagher studies the sharks who live in and around the infamous Bermuda Triangle to see why sharks are attracted to the area. The Bermuda Triangle is also known as the Devil's Triangle and is called so because many ships and aircraft have disappeared in the area mysteriously.
One of the sharks that are spoken about by Gallagher and his team is the cookiecutter shark. Odd name, right? However, the shark species is named so because of a peculiar wound it leaves on its victims. This shark is a parasite – meaning it feeds off larger animals without killing them. The cookiecutter shark is named after the cookie-shaped wounds that it leaves on the bodies of its prey. Several species – including bluefin tuna, great white sharks, spinner dolphins, and other large predators – have been observed with one or more scars caused by these sharks. This small fish is also known as the cigar shark because of its body shape. It lives in the deep-waters of warmer areas worldwide.
Relative to its body size, the cookiecutter has the largest teeth of all sharks. It uses them to take round chunks out of larger marine creatures – their trademark bites can be seen on large fish and whales of the deep ocean. The entire lower surface of the body (except for the darker throat) is bioluminescent, being able to emit a greenish glow. It is covered in tiny light-producing organs called photophores. These are thought to attract the attention of potential prey, giving this fish yet another of its common names: “luminous shark”.
How does the cookiecutter shark hunt? Since the shark swims closer to the surface of the water at night, predator fish will see it from below. From this vantage point, the glowing belly of the cookiecutter shark looks like a spot of sunlight or moonlight shining through the water. That perspective makes the luminous part of its body virtually invisible to predators. However, one wide stripe around the cookiecutter shark's neck does not glow. Fish can distinguish that non-glowing part. Since it appears much smaller than it is, the shark attracts predator fish looking for an easy snack. By luring the fish to come to it, the cookiecutter then has more power to bite them than if it tried to use its feeble strength to approach.
Once the predator goes in for the kill, the shark whips around and latches on to its opponent's flesh with the suction power from its fleshy lips. Digging its razor-sharp teeth into fish, the cookiecutter shark then spins its body around, carving out a cookie-shaped lump of meat like a wild melon baller. After the cookiecutter shark has taken its fill, it releases the fish. Fish can usually survive a cookiecutter attack, but the wound may fester or become infected.
'Sharks of the Bermuda Triangle' will air again on Nat Geo WILD on August 13, 6 pm ET.