Siphonophorae

Siphonophores (from Ancient Greek σίφων (siphōn), meaning "tube" and -φόρος (-phóros), meaning "bearing") are cnidarian animals of the hydrozoan order Siphonophorae. According to the World Register of Marine Species, the order contains 194 species described thus far.

Siphonophores are highly polymorphic and complex organisms, which blur the line between individual organisms ("regular" animals, built from organs and cells) and colonial organisms (like e.g. corals, where each polyp can in principle live on its own). Each specimen is composed of medusoid and polypoid zooids that are morphologically and functionally specialized. Zooids are multicellular units that develop from a single fertilized egg and combine to create functional colonies able to reproduce, digest, float, maintain body positioning, and use jet propulsion to move. Most colonies are long, thin, transparent floaters living in the pelagic zone.