Pocket sharks are just 5.5 inches long. That means the ultra-rare species could easily be carried around by anyone wanting a carnivorous pocket pet. Although these creatures are cute – resembling a tiny sperm whale – they may just take a bite out of anyone who tries to pick them up. What's more, only two have ever been found.

Pocket sharks were first discovered when a single member of the species was caught off the coast of Peru in 1979. The second specimen was accidentally caught in 2010 — during a catch designed, coincidentally, to analyze food eaten by sperm whales. Soon after being pulled from the ocean, these fish were frozen as samples for future analysis — and among them was the pocket shark, to be discovered years later.

Mollisquama, the genus into which pocket sharks have been placed, is most-closely related to Dalatiidae, which includes cookie cutter and kitefin sharks. These animals usually feed by taking small bites out of larger fish, although they will consume prey smaller than themselves from time to time.

"The pocket shark we found was only 5 and a half inches long, and was a recently born male. Discovering him has us thinking about where mom and dad may be, and how they got to the Gulf. The only other known specimen was found very far away, off Peru, 36 years ago," Mark Grace of NOAA said.

Their popular name comes not from their size, but from a distinctive pocket-like orifice located above the pectoral fin on the side of the animals.

Analysis of the new specimen of pocket shark has already provided researchers with information unknown from the 1979 example, including the discovery of a series of glands located along the abdomen of the fish.

Other rare sharks include the megamouth shark, distinguished by a comical-looking human face, resembling something off a totem pole. Fewer than 60 of these sharks have ever been seen.

Cookie cutter sharks have overgrown eyes for their size, housed in a worm-like head. The small shark attacks animals as large as dolphins, anchoring into flesh with its top teeth while biting away with the bottom, turning its body like a can opener to extract an oval bite of meat from its victim.

Frilled sharks exhibit heart-shaped heads and large pectoral fins resembling overgrown ears, like those on the Luck Dragon from the 1984 movie The NeverEnding Story.

The rare find of a pocket shark and anatomical comparisons to other similar species was detailed in the journal Zootaxa.

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