by REGINA NUZZO
When Neotrogla curvata insects mate, the female (top) penetrates the male. SOURCE/Yoshizawa et al./Current Biology
Brazilian cave creatures’s marathon sex sessions extract nourishment along with sperm from reluctant male.
In desolate caves throughout Brazil live insects that copulate for days, the female’s penetrating erectile organ sticking fast in a reluctant male’s genital chamber until he offers a gift of nutritious semen. Neotrogla seems to be unique among species with reversed sex roles — with choosy males and aggressive, promiscuous females — in also having swapped anatomy, researchers report1.
Not all animal species have a male penis, but because the evolution of body parts usually works through slow modification of existing structures, there would need to be a good reason for a female to develop a penetrating organ, says entomologist Kazunori Yoshizawa of Hokkaido University in Japan, a co-author of the study.
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Hold on tight
When the flea-sized winged insects mate, the female mounts the male and penetrates deep into a thin genital opening in his back. Membranes in her organ swell to lock her in, and multiple spiky spines act as grappling hooks to anchor her tightly to the male. (When researchers tried to pull apart two mating insects, the female was gripping so tightly that the male was accidentally ripped in half, leaving his genitalia still attached to the female.) The tip of the female’s penis fits neatly into the male’s genitalia to allow her to receive a large, teardrop-shaped sperm capsule over their 40–70 hours of copulation.
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