Water fleas 'mail' their eggs from pond to pond

I believe I posted an entry on my collection of "water fleas" as a child. Here's a bit of follow up....

Organisms that seem to appear out of nowhere have taxed some of the finest minds in history.

Aristotle, for example, was troubled by what he thought was the spontaneous appearance of aphids on his plants, and it took years until people realised that maggots came from flies.

Now biologists have figured out how water fleas – unable to survive outside of water – are still able to disperse between ponds.

Pond-dwelling insects call backswimmers are the culprits, they say, giving the fleas' eggs a lift as they fly between ponds.

Frank Van de Meutter and colleagues of the Catholic University of Leuven in Belgium put backswimmers (Notonecta) in a bucket of water with 1000 eggs of the Daphnia water flea.

Handy hairs

They allowed the backswimmers to take flight, caught them and examined them for the presence of Daphnia eggs.

Of 45 backswimmers caught in flight, 30 had eggs attached. The researchers found that the insects' hairy abdomens allowed the eggs to easily latch on, explaining how the Daphnia can hop from pond to pond.

"Even after the backswimmers were rather roughly caught with a bucket, Daphnia eggs remained attached to the body, especially on the hairy keel at the underside of the abdomen and on the haired parts of the legs," says Van de Meutter.

From: New Scientist