noun - Siphonophores or siphonophorae or siphonophora are an order of the Hydrozoa, a class of marine invertebrates belonging to the phylum Cnidaria. Although a siphonophore appears to be a single organism, each specimen is actually a colony composed of many individual animals. Most colonies are long, thin, transparent pelagic floaters. Some siphonophores superficially resemble jellyfish. The best known species is the Portuguese Man o' War. The species of siphonophore, the Praya dubia, has a a body length of 40–50m (130–160 ft) is another species of siphonophore and is one of the longest animals in the world.