It's not hard to find a collection of water in the woods this time of year, but how can you tell when you've found a vernal pool? Biologists have found that one very small creature is the one true indicator.
Diminutive, seemingly insignificant fairy shrimp are an important indicator species for biologists searching for vernal pools. These temporary ponds are usually formed by the melting snow and spring rain and are vital to the successful reproduction of many species. Although fairy shrimp are not present in all vernal pools, a body of water that contains them is always a vernal pool.
Hi, this is Iain McLeod for Something Wild.
Fairy shrimp are delicate crustaceans about one half to one and a half inches long and look very much like the infamous Sea Monkeys you may have kept as a child. They may be pale translucent green or gray, but are often an orangey-pink color. Fairy shrimp swim upside-down, on their backs, by rhythmically waving their many leg-like appendages. These appendages also collect the shrimp?s food -- minute algae, bacteria, detritis and protozoa.
Fairy shrimp cysts hatch as soon as there is water in the pools. Individuals grow quickly and can complete their life cycle in as little as 16 days ? an important adaptation considering that their watery homes can dry up in a short time. The adults mate and cysts develop in the female's brood pouch. Once fully formed, they are released and sink to the bottom of the pool. The cysts must dry and be re-submerged before they will hatch. That?s why the presence of fairy shrimp indicates that a pool is temporary or seasonal. The cysts are very hardy, however, and may stay dormant for decades until activated by water.
Vernal pools are among the most threatened habitats in the world. When you visit a possible vernal pool, watch for the wee fairy shrimp slowly swimming in shafts of sunlight. If you find them, you can be certain you?ve found a vernal pool! For more information on fairy shrimp and vernal pools, visit www.vernalpool.org.
Something Wild is a joint production of New Hampshire Audubon, New Hampshire Public Radio, and the Society for the Protection of New Hampshire Forests.
For Something Wild, I?m Iain MacLeod.
If you have a natural history question that you would like answered on Something Wild, email us at somethingwild@nhpr.org.
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