There are more than 400 known shark species but many of them are rare. One of these rare species is the pocket shark, one of which was recently identified by scientists.

The 5.5-inch rarity is just the second of its kind to be discovered, a male believed to be just a few weeks old when it was caught in 2010 in the Gulf of Mexico.

The only other pocket shark reported is a female specimen caught in the southeast Pacific Ocean's Nazca Submarine Ridge in 1984. Though the sharks could easily fit in one's pocket, they are not named for their size. Instead, it's for the pocket or orifice located above their pectoral fin.

Earlier in the year, a rare shark was also pulled up from the waters of Australia, a frilled shark thought to have inspired tales of sea monsters. It makes a lot of sense to think that, given the shark still highly resembles its ancestors from the dinosaur era. This certain frilled shark caught was six feet long and had a mouth full of teeth. It had a slender body like that of an eel, an appearance that may have been the source of stories about sea serpents.

Other rare species of sharks include:

• The Bahamas sawshark. Living in waters more than 1,000 feet deep, the Bahamas sawshark can grow up to 4.5 feet. It is characterized by a flattened snout with sharp spikes for digging up and killing prey, with two long beards to aid in finding targets.
• The Indonesian speckled carpetshark. From the bamboo shark family, the Indonesian speckled carpetshark is one of the few shark species that "walk" along the ocean's floor by supporting their body with their pectoral fins. It is active at night, using the cover of darkness to feast on crustaceans.
• The megamouth shark. First discovered in 1976, the megamouth shark has only been reported less than a handful of times, mostly probably because it lives in deep water. Similar to other larger shark species, it feeds on plankton.
• The speartooth shark. One of six shark species that can live in freshwater, the speartooth shark has been reported in New Guinea and northern Australia. It can grow up to nearly 10 feet and has adapted to hunting in dark murky waters for big fish.
• The striped catshark. Also known as the pyjama shark, the striped catshark is a small shark species, growing up to just about three feet. Found in South Africa, it likes to hide in cracks in shallow reefs to catch prey. When threatened, it also hides, rolling up and covering its head to go unnoticed.