Ant sperm swim as a team

A sperm swim team could make a desert ant a reproductive winner. A study published June 10 in Biology Letters finds that grouping sperm together in many-cell masses makes them swim faster, with possibly better reproductive results.

Reproduction is tough for the male desert ant Cataglyphis savignyi. He dies soon after mating, and the female he mates with will quickly take many other partners. After mating, the female stashes sperm from several males in a specialized organ called a spermatheca before using some of the stored sperm to fertilize her eggs.

With that kind of competition, the male desert ant has evolved a teamwork approach to be the first to get sperm into storage. He releases sperm in bundles of about 50 to 90 bound together at the head with caps of sticky proteins, Morgan Pearcy and colleagues from the Université Libre de Bruxelles in Belgium found.

Sperm bound together swam 51 percent faster than the few that voyaged alone. Slower sperm may not make it into the spermatheca, blowing their chance of fertilization. The researchers hypothesize that the swim team strategy may have evolved to take advantage of speed in numbers.