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Clione limacina Limacina helicina  
Limacina helicina  

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Pteropods - sea angels & sea butterflies

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Pteropod means "wing footed", referring to modification of this pelagic snail's foot that allows it to swim through the water. The group is somewhat artificial; it contains a sub-group of animals with shells, and a sub-group without shells, that are not closely related. Both are generally present year round in low numbers, with the shelled forms having been reported to form swarms or bloom under favorable conditions. They can be important items in the diets of fish, sometimes selected over other abundant prey.

The shelled group is primarily filter feeders. They swim to toward the waters surface and then secrete at mucus net that acts like a parachute as they sink. The parachute traps food as water passes through it, then the animals sucks it in and consumes the parachute plus all the food stuck to it. The naked group, sometimes called sea-angels, is specialized to eat the shelled group and some other soft-bodied animals.

Relatively little is known about pteropods in general other than distribution. They are thought to be primarily surface water species. It is thought that they have 1-2 generations per year in the subarctic.

There are 2 species common in the subarctic, plus serval species encountered only rarely.

Page Author: Russ Hopcroft
Created: Jan 1, 2010