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  Dimophyes arctica Dimophyes arctica
Marrus orthocana    
Nectopyramis diomedeae    

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Siphonophores

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The siphonopores are a subgroup within the hydromeduae that are distinguished by the presence of a colonial phase with specilalized individuals, and the lack of a benthic phase. The Portuguese-man-o-war is an example of a siphonophore. The siphonpores are further divided into 3 major groups, two of which occur in the Arctic: the Physonects which have larger colonies with gas floats, and the Calycophorans that often resemble arrow heads.

Within the colony, individuals specialize for different roles. Specialization is most extreme in the Physonects were some parts are specialized to act as floats, some to swim, some to catch food, some to eat and digest the food, some to reproduce, and some to act as armor. The Calycophorans typically have only 1 or 2 individuals per colony and an alternating body-form over their life cycle. Colonies generally frament completely once collected.

Siphonophores are generally not found in surfcae waters, but prefer deeper depths where the colony can spread out fishing. They can be among the more adundant predators in mid-waters. A colony of the Calycophoran Marrus orthocana can be several meters long when feeding, with a long curtain of tenacles hanging from it, while most physonects are only several centimeters and more analogous to a long-line fisherman, reelling in their typically crustacean prey once caputered.

We know little for sure about how long most species live in the Arctic. The larger species might live several years, while the smaller species may have relatively short lives. There are 8 species of siphonophores known to exist in the arctic.

Page Author: Russ Hopcroft
Created: Aug 20, 2010

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