What is a Siphonophore?

Though they may sometimes be mistaken for jellies, there's much more than meets the eye when it comes to siphonophores

Smithsonian National Museum of Natural History

Dandelion Siphonophore (2011) by NOAAOriginal Source: NOAA Office of Ocean Exploration and Research, Galapagos Rift Expedition 2011

The siphonophores are an order of marine animals in the phylum Cnidaria (the same phylum containing jellyfish). There are about 200 different species of siphonophores known.

Siphonophore (2018-04-28) by NOAAOriginal Source: NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.

Although they superficially resemble jellyfish, each siphonophore animal is actually a colony of many genetically identical individuals called zooids.

Siphonophore (2017-09-22) by NOAAOriginal Source: NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts

Each zooid is specialized to serve a particular function (such as swimming, feeding, prey capture of reproduction) within the colony—so much so that individual zooids cannot survive alone.

Portugese Man-O-War (Physalia physalis) (2002) by NOAAOriginal Source: NOAA/OER Islands in the Sea 2002,

The infamous and venomous Portuguese man o' war is a member of this order. It lives at the water’s surface, trawling the depths for suitable prey with its long tentacles. 

Physonect Siphonophore (2021-07) by NOAAOriginal Source: NOAA Ocean Exploration, 2021 North Atlantic Stepping Stones: New England and Corner Rise Seamounts

Most siphonophores live in the deep ocean where there is no light other than the light emitted by organisms. Even some siphonophores can emit light. A species in the Erenna genus found off the coast of Monterey, California has stinging cells that glow red, probably to attract the small fish upon which it preys.

This species is only the second life form known to produce a red light, the first being the scaleless dragonfish (Chirostomias pliopterus).

Siphonophore (2017-09-22) by NOAAOriginal Source: NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts

For more information on siphonophores and other marine species, visit the Smithsonian Ocean portal here.

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