Tiny cricket possesses world’s ‘biggest’ testicles

November 11th, 2010 - 4:32 pm ICT by IANS  

London, Nov 11 (IANS) It may only be half the size of a human finger, but the tuberous bushcricket has the biggest testicles in the world relative to its body weight!

Scientists have discovered that the male of the specie has testes which are 14 percent of its whole body mass. It would be the human equivalent of a man carrying testicles weighing as much as five bags of sugar each, according to the Royal Society Journal Biology Letters.

This beats a species of fruit fly (Drosophila bifurca), thought to be the previous record holder for the biggest testes as a percentage of male body mass, at 10.6 percent, reports the Daily Mail.

But despite this, the bushcricket does not necessarily produce the largest amount of sperm - contrary to traditional thinking - according to the study.

Lead researcher Karim Vahed, ecology reader at the University of Derby, UK, said: “We couldn’t believe the size of these organs; they seemed to fill the entire abdomen. We are also interested in the reason why they are so large.

“An almost universal evolutionary rule appears to be that such variation in relative testes size is linked to female mating behaviour.

“Testes tend to be larger in species where females are more promiscuous, as has been demonstrated in various species in fish, birds, insects and mammals.

“But at least two hypotheses could account for this pattern - sperm competition on the one hand and male mating rate on the other.

“Yet our study appears to be the first study to show that, in the case of the tuberous bushcricket, bigger testes don’t necessarily produce more sperm per ejaculate.”

In the study, Vahed, Derby biology graduate Darren Parker and James Gilbert from the University of Cambridge compared relative testes size across 21 species of bushcricket.

They found testes were proportionately larger in species where females mated with more males - female tuberous bushcrickets mate with up to 23 different males in their two-month adult life.

But they also found the bushcricket did not produce more sperm - in fact they produced less ejaculate.

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