Siphonophora

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{{Taxobox | color = pink | name = Siphonophora | image = portuguese man of war.jpg | image_caption = Portuguese Man o' War, Physalia physalis | regnum = Animalia | phylum = Cnidaria | classis = Hydrozoa | ordo = Siphonophora | ordo_authority = Eschscholtz, 1829 | subdivision_ranks = Families | subdivision = See text. }}

Siphonophora is an order of the Hydrozoa, a class of marine invertebrates belonging to the phylum Cnidaria. They are colonial, and the colonies may superficially resemble jellyfish. The best known species is the Portuguese Man o' War. Each Man o' War is a colony.

They are composed of medusoid and polypoid zooid that are morphologically and functionally specialised. The integration of the zooids can be so strong that the colony attains the character of an individual.

A siphonophore from the genus Erenna has been discovered at a depth of around 1,600 meters off the coast of Monterey, California. The individuals from these colonies are strung together like a feather boa. They prey on small animals using stinging cells. Among the stinging cells are stalks with red glowing ends. The tips twitch back and forth creating a twinkling effect. It is theorized that twinkling red light attracts small fish that have been found eaten by these siphonophores.

While many sea animals produce blue and green bioluminescence, this siphonophore is only the second found to produce a red light (the first being the scaleless dragonfish).

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