Siphonophorae is an order of Hydrozoans, a class of marine organisms belonging to the phylum Cnidaria. According to the World Register of Marine Species, the order contains 175 species. Siphonphores are colonial hydrozoans that do not exhibit alternation of generations, but instead reproduce asexually through a budding process.
About Siphonophorae in brief
Siphonophorae is an order of Hydrozoans, a class of marine organisms belonging to the phylum Cnidaria. According to the World Register of Marine Species, the order contains 175 species. Each specimen is in fact a colonial organism composed of medusoid and polypoid zooids that are morphologically and functionally specialized. Most colonies are long, thin, transparent floaters living in the pelagic zone. Some siphonophores emit light to attract and attack prey. Siphonphores are colonial hydrozoans that do not exhibit alternation of generations, but instead reproduce asexually through a budding process. A single bud called the pro-bud initiates the growth of a colony by undergoing fission. Each zooid is produced to be genetically identical; however, mutations can alter their functions and increase diversity of the zooids within the colony. Some species can be confined to a specific location, however some can be found in an area of the ocean that is not confined to one specific location. A siphonophile is a complex aggregate of many nectores, which are concentrated towards the top of the siphon, and their function is turning and adjusting the orientation of the larger individuals. Individuals are genetically identical, but depending on where each individual nectore is positioned, their function differs by their position in the colony, and so their movement is determined by the nectophore’s orientation.
The most common body plan is Cystonecta, Physonects, and CalycophorAE. The group of zooids has a tentacle used for capturing and digesting food. They use a pneumatophore, a gas-filled float, on their anterior end and mainly drift at the surface of the water. They also use a nectosome to pump the water back in order to move forward. CalyCophorans differ from cystonects and physonectS in that they have two nectongores and no pneumatogores. The majority of siph onophores live in the deep sea. Smaller, warm-water siphonophonophores typically live. in the epipelagic zone and use their tentacles to capture zooplankton and copepods. Larger siphonphore species live in deeper waters, as they are generally longer and more fragile and must avoid strong currents. They mostly feed on larger prey. Siphons are most often pelagic organisms, yet level species are benthic. Smaller siphons can be seen in the northern hemisphere of the Earth. The largest siphons are found in the southern hemisphere. The siphonops are the most common species in the Northern Hemisphere.