Cookiecutter sharks are deep-water marine animals that live below 3,281 feet under the surface of the ocean and migrate upwards at night to hunt and feed. They have a long, skinny body, and they’re tiny little things, compared to most other sharks. Males reach about 16 inches at maturity and are smaller than the 22-inch females.

Like the very strange goblin shark, cookiecutter sharks have some bizarre and rather creepy features that other sharks don’t have.

Domicile in the Deep

Cookiecutter sharks are a small species of dogsharks, and they live in deep, warm ocean waters all over the world, usually in the vicinity of an island. The cookiecutter shark’s liver accounts for 35 percent of its body weight, and it’s full of low-density oils that help it remain neutrally buoyant in the depths and conserve energy. Cookiecutters have very large eyes for its body size, probably to help them see better in the dark depths.

Cookiecutter: The Glow-in-the-Dark Shark!

Cookiecutter sharks have light-emitting organs called photophores on their underside that glow bright green in the dark. This is known as bioluminescence, and scientists believe that one of its functions is to eliminate an animal’s shadow when prey is looking up at them from below.

What’s interesting about the photophores on the cookiecutter is that they stop at the section of the underbelly where the gill slits are located, and as such, large sea creatures tend to mistake it for a smaller fish. As they approach for the kill, the clever cookiecutter turns the tables and attacks.

Fearsome Feeding Habits

Now, hold on to your lunch, because the way the cookiecutter feeds is a little weird and unappetizing, and it has everything to do with its name.

Cookiecutter sharks typically feed on prey that’s much larger than they are, such as dolphins, tuna, and stingrays, as well as mammals like whales and seals. So how does a teeny shark that’s less than two feet long manage to enjoy such large fare?

Well, it all starts with their suctorial lips. Yes, lips. Cookiecuttes sharks have lips, and when prey approaches the bioluminescent creature thinking they’re going to enjoy a “light” snack, the cookiecutter attaches itself to the animal with its lips and sharp, pointy upper teeth. Firmly attached to the prey’s flesh, the cookiecutter spins, carving out a plug of flesh about two inches across and two and a half inches deep.

Sound painful? It is. A few years ago, a long distance swimmer named Mike Spaulding was bitten by a cookiecutter shark during a nighttime swim off the coast of Hawaii, and he lost a two-inch wide by three-quarter inch deep, cookie-shaped blob of flesh to the little beast. The pain was excruciating, as you might imagine.

But don’t worry. Cookiecutter sharks live in the deep, and they only come to the surface to hunt and feed at night. So unless you’re swimming in the middle of the ocean in the dark, there are more pressing things to worry about than losing a chunk of flesh to a cookiecutter shark. And while the cookiecutter’s feeding habits definitely harm their prey, they’re not necessarily fatal.

Remarkable Reproduction Process

Sharks reproduce in one of three ways.

Oviparous sharks lay a sac called a “mermaid’s purse” that’s full of eggs. The purse attaches itself to a rock or another surface to keep it safe until the eggs hatch.

Viviparous sharks grow live baby sharks in their uterus and give birth to live pups.

The cookiecutter shark is an ovoviviparous shark, which combines the best of both worlds. It all starts with eggs that are fertilized by a male. The developing pups feed on the egg yolk for awhile, and then they hatch – inside the mother’s body. Soon after, the mother cookiecutter gives birth to live shark pups, which swim off in search of food and to avoid becoming a post-natal snack for Mom. A typical cookiecutter shark litter will have between six and 12 pups after gestating for 12 to 22 months.

One Sub, Please

Back in the 1970s, cookiecutters were a nuisance to submarines, which probably looked like some giant, delicious fish to the sharks. The sonar domes at that time were constructed of neoprene, and cookiecutters had a nasty habit of doing their bite-suck-and-spin routine on the domes. The oil inside, which is the medium for transmitting sound, would leak out and leave the submarine navigating blindly through the ocean. Nowadays, the sonar domes are covered in fiberglass to keep them safe.

Terrifying Triangular Teeth

Cookiecutters have the largest teeth of any shark, relative to their size. Most sharks have multiple rows of teeth so that when they lose one, the tooth behind it moves forward to replace it. The average number of rows is 15, although some have just three rows and the fearsome bull shark has a whopping 50.

But cookiecutter sharks have no rows. The upper jaw contains between 20 and 37 small, sharp, pointy teeth to help them glom onto their prey. The lower jaw contains between 25 and 31 larger teeth, triangular in shape and super sharp. The bigger the shark, the more teeth it has.

The bottom teeth aren’t independent of the others, but rather, they’re connected at the base, probably to keep them in place while they’re cookie cutting holes in some poor seal’s flesh. When one bottom tooth goes, they all go. And when they go, the shark ingests them, which helps them maintain healthy calcium levels.

A Shark by Many Other Names

Since its discovery in 1824, the cookiecutter shark has had three scientific names. They’re currently (and probably finally) known as Isistius brasiliensis. The genus name is a nod to Isis, the Egyptian god of light. The species is named for Brazil, one of its favorite habitats.

There are three species of cookiecutter shark, and one of them is the Isistius plutodus, or the large tooth cookiecutter, whose bottom teeth are much bigger and more fearsome than those of Isistius brasiliensis.

Cookiecutter sharks are also commonly known as “cigar sharks” due to their long cigar-shaped body that features a dark band around their gill slits.