Biggest testicles (insect)
The animal which has the biggest testicles in relation to its body weight is the katydids bushcricket, specifically the species Platycleis affinis, that accounts for up to 14% of its body weight. Discovered by ecologist Karim Vahed from the University of Derby, and his team, they report:
"The absolute mean mass of a single testis ranged from 2.7 mg in Metrioptera roeselii to 70.1 mg in Platycleis affinis (electronic supplementary material, S1). In proportion to total male body mass, the smallest testis was found in G. glabra and Ephippiger ephippiger (combined testes = 1% of male body mass in both species), while the largest was found in P. affinis (combined testes = 13.8% of male body mass)."
- Jason Palmer, "Bush cricket testicle size clue to promiscuous mating", BBC News, 10 November 2010
- Christine Dell'Amore, "Cricket Has World's Biggest Testicles (But Puny Output)", National Geographic News, November 9, 2010
- Karim Vahed, Darren J. Parker, and James D. J. Gilbert, "Larger testes are associated with a higher level of polyandry, but a smaller ejaculate volume, across bushcricket species (Tettigoniidae)", Biology Letters 23 April 2011 vol. 7 no. 2 261-264 (full text)