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A male and female Fairy Shrimp, Anostraca
Photo used by permission of
the Vernal Pool Association.

Fairy Shrimp


One of the first signs of spring (for me at least) is the appearance of swarms of Fairy Shrimp in fishless, woodland ponds. These odd and unlikely creatures seem to have come straight from the Burgess Shale where they swim on their backs and appear in sometimes incredible numbers - just in time for the hatching salamander larvae who begin to appear now as well.

Fairy Shrimp are short-lived in their adult form living at most for a little over two weeks. Once the water begins warming these creatures disappear as well. But during their tenure in the pool they engage in a veritable orgy of reproduction with each female laying dozens and even hundreds of eggs.

The females lay two types of eggs: thin-walled summer eggs that hatch during the coming summer; and thick-walled winter eggs. These winter eggs lie in the mud for the rest of the year, resistant to heat, drying and clumsy land dwellers like ourselves who often trample through the dried pools during the summer. Eggs can be spread from pool to pool by animals - waterfowl, dogs and raccoons - when eggs disturbed from the bottom attach to feathers or fur, or they can be spread by the wind when the pool dries out and the mud encasing them turns to dust. But once the winter rains refill the pools the eggs develop, hatch and the cycle begins again.

While they're not found in every pool an excellent way to check for their presence is to visit one some warm night in late winter or early spring. Turn on your flashlight and hold it steady in one spot. If Fairy Shrimp are present they'll be attracted to the light and within five minutes a small cloud of swimming shrimp should appear.

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Copyright © 2005 Jim Jung
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