http://www.youtube.com/watch?v=KT1TSbarW1U&feature=player_embedded
...an eerily fantastic creature that appears to be a single, large organism, but which is actually a colony of numerous individual jellyfish-like animals that behave and function together as a single entity. The individual units, called zooids, all share the same genetic material and each perform a specialized role within the colony. The best-known siphonophore is the poisonous Portuguese Man o' War.