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Nature Notebook – Mayfly Nymphs

The variety of organisms that we find during our pond explorations is a pretty good indicator that Sarett’s wetlands have good water quality. Recent student surveys included mayfly nymphs, considered to be a major indicator of good water.

These delicate creatures walk along eating detritus (bits of dead stuff) on the bottom of the pond or streams. The fanlike gills on their abdomen move constantly, giving them a feathery look. The gills have a couple of function. They control the flow of water through the body. The angle at which the gills make water flow off the body is thought to be an anti-predator tactic.

Most importantly, the gills collect oxygen. They can only do this in water with high levels of dissolved oxygen and very little pollution.

In a few weeks we won’t be able to find the nymphs in the water. They will have finished their metamorphosis into the terrestrial adult stage. An observer lucky enough to time a visit will witness a swirling mass of bodies flying above the water. For the species, there is safety in numbers from predators.

Those that survive the emergence must then quickly mate and lay eggs before they starve to death. An example of one of nature’s quirky design plans, adult mayflies do not have mouthparts. Perhaps this forces them to concentrate on their procreation task.