The Guardian reports on the bizarre world of Animal sex

Erica McAllister is excited (perhaps, in the context, not the most felicitous choice of word, but never mind. She's passionate, too, but that's not much better). "Flies," she enthuses, "are the best, because they're everywhere, and they do everything. They get up to the craziest stuff. Amazing genitalia. And some wild strategies."

Downstairs in the Natural History Museum's magnificently arched Jerwood Gallery, staff are (as it were) mounting Sexual Nature, a new exhibition exploring the diverse and often startling sexual and reproductive behaviour of animals (or, as the museum's posters coyly put it, "nature's most intimate secrets"). It's the museum's first adult exhibition, aimed at those over 16, and containing what the same publicity calls "frank information and imagery about sex", so everyone is, naturally, quite excited.

Curators talk about the exhibition on the Guardian's Science Weekly podcast Link to this audio

"I'm looking forward to seeing visitors' reactions," says Richard Sabin, senior curator of the museum's mammal group, from whose collections a number of specimens – including a red deer stag, a hyena, chimpanzees and Guy the gorilla – have been selected for display. "They'll have seen animal courtship on television, but nothing quite as, um, graphic as here. It'll get them talking, certainly. What we hope is that it wipes away the whole thing about this being a taboo subject. Because, of course, nothing could be more natural."

Natural it may be, but animal reproduction can be a mighty strange business. Barnacles, for instance, have a penis 30 times their body length. Male snakes have a forked organ, allowing them to dodge the female's tail and penetrate from either direction. Hedgehogs plug their partner's vagina with excess sperm to stop anyone else's getting a look in. Blue fairy wrens have testicles 25% their body weight. The female hyena picks and dumps her male as she sees fit, and has even evolved genitalia that look like a male's.

Still, flies are best, says McAllister (she would: she's the musuem's entomology collections manager). The male stalk-eyed fly, she explains, pointing to a case of them – a tiny fraction of the museum's 20 million-strong insect collection – "takes in air and its eyes come out on stalks. Then it blows out again, and the stalks harden and set, for ever. And it's the ones with the widest stalks that get the most action. Male antler flies do the same, except they use their antlers to head-butt each other – to see off rivals."

There's not much to beat the mating ritual of the dance fly, though. "They're into gift-giving," says McAllister. "The males catch a smaller fly and kind of dangle it in front of the females as they dance. But they've wrapped their present up in a little silk balloon, so it takes her a while to get at it – and while she's busy, he has his wicked way. Brilliant. And some of the males are even more devious. Once they've done the deed, if the gift isn't finished they'll just take it back and give it to another girl. Like a half-eaten box of Milk Tray, except it seems to work. And some really naughty ones haven't got a gift at all, they just pretend. It's crazy stuff."

you can read the rest of the article here: http://www.guardian.co.uk/science/2011/feb/10/animal-sex-sexual-nature-exhibition