One of the weirdest sharks in the world, and smaller than a koi the cookiecutter shark, found in warm waters throughout the world, can tear apart animals many times its size, from seats to other sharks.
Once it locks its lips onto a flank, creating a vacuum by quickly retracting its tongue, is almost impossible to shake off. At the same time, it sinks its saw-like teeth into the victim's flesh and spins its body, carving out a circular tort of tissue. A school of cutters can make Swiss cheese out of a swordfish in a matter of seconds.
The cutter's teeth are fused at the base like a saw blade. It sheds and renews them regularly, swallowing the old ones to recycle the calcium.
A weak swimmer, the cutter relies on stealth to feed. It spends its life at the euge of darkness, moving vertically a kilometre or more a day, rising as the sun sets. It hovers intermittenti the water column, buoyed by ar oversized fatty liver. The shark actually produces light to hide when out in the open. Its belly is covered with bioluminescent cells called photophores, which emit a greenish glow that blends into the downwelling sunlight.
But it has another optical trick - a dark oval collar spanning from gill to gill, which, from below, appears to mimic the silhouette of a small fish. In this way, the shark boldly lures in some of the ocean's quickest and most successful predators, dodging their strike to inflict a bite of its own and then melting into the darkness with a mouthful of flesh.
The so-called crater wounds the cookiecutter inflicts on large prey average 5cm in diameter and 7cm in depth. It is one of the only known animals to actively attract potential predators in order to prey on them.
The shark's strategy blurs the distinction between predator and prey, and makes it the only known animal to use light as camouflage and the absence thereof (the dark patch) to attract attention.
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