Cricket sets testicle size record

The tuberous bushcricket's testicles account for 14 percent of its body weight.

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Wed, Nov 10 2010 at 1:09 PM

The male tuberous bushcricket has testicles that amount to 14 percent of its body weight.

BIG WINNER: The male tuberous bushcricket, Platycleis affinis, has testicles that amount to 14 percent of its body weight. (Photo: S. Taylor/University of Derby)

A species of cricket has broken an unlikely world record: largest testicles in relation to body weight.

The tuberous bushcricket's testicles account for 14 percent of its body weight. To put that in perspective, the testicles of a man weighing 200 pounds (91 kilograms) with that ball-to-body ratio would weigh 28 pounds (12.7 kilograms). [Image of cricket and its testicles]

The bushcricket, the anatomical extremes of which are reported Nov. 9 in the journal Biology Letters, edges out the record of a species of fruit fly, Drosophila bifurca, whose testes to body weight ratio has been recorded as 10.6 percent.

Oddly enough, the researchers report, the cricket's large testicles don't produce greater volumes of semen per ejaculate. In fact, they produced less voluminous sperm than smaller testicles.

"Traditionally it has been pretty safe to assume that when females are promiscuous, males use monstrously sized testicles to deliver huge numbers of sperm to swamp the competition — even in primates," study researcher James Gilbert of the University of Cambridge said in a statement. "Our study shows that we have to rethink this assumption. It looks as though the testes may be that big simply to allow males to mate repeatedly without their sperm reserves being exhausted."

The tuberous bushcricket joins a veritable who's-who list of animals with strange genitalia, including:

Single-testicled carabid beetles
Rodents that enjoy a mating advantage thanks to their long penises
Polar bears whose penises are shrinking because of pollutants
Ducks with penises like corkscrews (and vaginas to match)
Smart bats with small testicles
And to round out the list, some male fruit bats (Rousettus aegyptiacus) have testes that are 2.15 percent of their body mass, whereas their brains are only 1.70 percent. [See the male fruit bat's genitalia]

This article was reprinted with permission from LiveScience.

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