Jellyfish
Drifting at any depth in all the world’s oceans, these creatures range from an Arctic species with a bell the size of a car, to a venomous microscopic Australian. Carnivorous predators, jellyfish swarm around our coasts and litter our beaches, yet we know surprisingly little about them. Some of the most recognisable species don’t even qualify as true jellyfish. One such, a Portuguese Man of War (Physalia physalis), its inflated bladder keeping it poised at the surface, is not even a single animal, but a sizeable colony containing four types of minute, highly modified polyps.