Elusive Male Water Fleas Spotted

Never before seen male water fleas have finally been spotted in a University of Buffalo laboratory.

Male water fleas are rarely produced and for many species, have never been observed. In stable environments, female water fleas usually reproduce asexually, creating populations of females that are essentially identical to each other.

The image above shows a male water flea of the Bosmina genus, a group that plays a major role in freshwater food webs.

Water fleas are nearly microscopic organisms that have transparent bodies. Despite their name, water fleas are not really insects, but crustaceans like lobsters and crabs. Water fleas can be found in lakes, ponds and other bodies of freshwater.

"People use water fleas as aquatic coal-mine canaries," said Derek Taylor, a biologist from the university who was involved in the study. "They are good indicators of environmental change."

To stimulate the production of males, the researchers exposed four distantly related species of water fleas to a crustacean juvenile hormone called methyl farnesoate (MF). The hormone is known to determine sex in other species of crustaceans and insects.

The experiment demonstrates that pesticides that mimic MF could have much broader effects than initially believed, Taylor said.

"Because the same MF hormone affects a broad range of crustaceans, any insecticide that mimics MF also may affect a large number of species in freshwater communities."

The study was detailed in a recent issue of the journal for the Proceedings of the Royal Society: Biological Sciences.