Siphonophora
| Siphonophores | |
|---|---|
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| Portuguese Man o' War, Physalia physalis | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hydrozoa |
| Subclass: | Leptolinae |
| Order: |
Siphonophorae Eschscholtz, 1829 |
| Suborders | |
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See text |
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| Synonyms | |
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Siphonophora Eschscholtz, 1829 |
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See text
Siphonophora Eschscholtz, 1829
The Siphonophorae or Siphonophora, the siphonophores, are an order of the Hydrozoa, a class of marine animals belonging to the phylum Cnidaria. Although a siphonophore appears to be a single organism, each specimen is actually a colony composed of highly specialised individual animals called zooids. Most colonies are long, thin, transparent pelagic floaters. Some siphonophores superficially resemble jellyfish, one example being the venomous Portuguese man o' war (Physalia physalis).
Another species of siphonophore, Praya dubia, is one of the longest animals in the world, with a body length of 40–50 m (130–160 ft). The term originates from the Greek siphōn "tube" + pherein "to bear".
Siphonophores are of special scientific interest because they are composed of medusoid and polypoid zooids that are morphologically and functionally specialized. Each zooid is an individual organism, but its integration with others is so strong that the colony attains the function of a larger organism. Indeed, most of the zooids are so specialized, they lack the ability to survive on their own. This is somewhat analogous to the construction and function of multicellular organisms; because multicellular organisms have organs which, like zooids, are specialized and interdependent, siphonophores may provide clues regarding the evolution of more complex bodies.
Like other hydrozoans, certain siphonophores can emit light. A siphonophore of the genus Erenna has been discovered at a depth of around 1,600 m (5,200 ft) 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. Twinkling red lights are thought to attract the small fish eaten by these siphonophores.
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