Some fleas have more genes than us?

A tiny, translucent water flea that can reproduce without sex and lives in ponds and lakes has more genes than any other creature, said scientists who have sequenced the crustacean's genome.

Daphnia pulex, named after the nymph in Greek mythology who transforms into a tree in order to escape the lovestruck Apollo, has 31,000 genes compared to humans who have about 23,000, said the research in the journal Science.

Often studied by scientists who want to learn about the effects of pollution and environmental changes on water creatures, the almost-microscopic freshwater Daphnia is the first crustacean to have its genome sequenced.

But just because this creature -- viewed as the canary in the gold mine of the world's waters -- has more genes doesn't necessarily mean they are all unique, explained project leader John Colbourne.

"Daphnia's high gene number is largely because its genes are multiplying, by creating copies at a higher rate than other species," said Colbourne, genomics director at the Center for Genomics and Bioinformatics.

Daphnia has a large number of never-before seen genes, as well as a big chunk of the same genes found in humans, the most of any insects or crustacean so far known to scientists.

"More than one-third of Daphnia's genes are undocumented in any other organism -- in other words, they are completely new to science," said Don Gilbert, coauthor and Department of Biology scientist at IU Bloomington.

These unique and previously unknown genes are "involved in response to the environment," the study said.

James Klaunig, professor of environmental health at Indiana University Bloomington, said the genome will help scientists study the effect of environmental pollutants on humans.

"Genome research on the responses of animals to stress has important implications for assessing environmental risks to humans," Klaunig said.

"The Daphnia system is an exquisite aquatic sensor, a potential high-tech and modern version of the mineshaft canary," he said. "With knowledge of its genome... the possible effects of environmental agents on cellular and molecular processes can be resolved and linked to similar processes in humans."

The water flea can be found throughout North America, Europe and Australia.

The Daphnia Genomics Consortium, led by the Center for Genomics and Bioinformatics at IU Bloomington and the U.S. Department of Energy's Joint Genome Institute, included more than 450 investigators around the globe.