The Lion's Mane Jellyfish

This huge jellyfish, confined to the icy waters of the Antarctic, gently propels itself through the water, expanding its pink folds into an umbrella shape. They get their name from the fact they've got loads of long, thin hair like tentacles. For most of their lives, they swim close to, or at the bottom of the ocean, feeding on shrimp, zooplankton and other small fish. It feeds in a number of different ways, from killing small animals with stinging cells on their tentacles. As far as human contact is concerned, stings just cause localised redness and temporary pain- in healthy people their stings aren't known to be fatal. Vinegar can also be used to 'deactivate' the sting but due to the large number of tentacles, you need to seek medical attention straight after exposure. In 2010, it was estimated that 150 people were thought to have been stung from the remains of a lion's mane jellyfish which had broken up into countless pieces on the coast of New Hampshire in the US.  Given the sheer size of the jellyfish, scientists reckon that the incident was probably caused by just one jellyfish.