I beg to differ about spider sex — it’s perfectly normally weird, but then I have been spending a fair amount of time trying to encourage spiders to have sex. Mainly what I’m concerned about is that it’s too infrequent, and they seem to have seasonal depression. But OK, it is interesting, as this video demonstrates.

You know what’s kinky, though? The video mentions that “some flies have a female who penetrates the male to collect sperm”. Not spiders, but barklice (Neotrogla), which aren’t flies and aren’t lice, but a kind of true bug, have completely reversed sex roles.

The female has a penis-like protrusion called a gynosome, which is erectile and curved. The male has no such organ; he has an internal chamber instead. When she penetrates him during sex, he delivers sperm into a duct in her gynosome, which leads to a storage organ. He still ejaculates, but he does so inside his own body, not hers.

Neotrogla sex can last for days, so it’s important for the duo to stabilise themselves. The female does it by inflating the base of her gynosome inside the male. It’s covered in patches of tiny spines, which help to anchor her in place for her sexual marathon. You can find similar spines on the penises of many male animals where they provide extra stimulation during sex (as in cats, mice and chimps) or inflict horrendous wounds on the females (as in the seed beetle).

In Neotrogla, the spines are such good anchors that it’s impossible to separate a mating pair without killing the male. As Yoshizawa writes, “Pulling apart coupled specimens (N. curvata; n = 1) led to separation of the male abdomen from the thorax without breaking the genital coupling.” In other words: We tried yanking one pair apart; it didn’t work and the male kinda broke.

See? Spiders are perfectly ordinary, mundane, familiar little creatures. No pegging involved.