Gallery: Animal Sex Is Dangerous and Horrifying. So Why Does Sex Exist at All?
London Natural History Museum01Linophryne-sp
Deep-sea anglerfish females like this one dwarf the males, so much so that the male doesn’t even look like the same species. A male will bite onto his lady friend, then fuse his face to her body. He lives the rest of his days like this, [releasing sperm when she releases eggs](http://stag-mantis.wired.com/2013/11/absurd-creature-of-the-week-anglerfish/). That little bump at the back of her belly? That's her husband.
Oceans IQ02The-bizzare-pearlfish
Not only does the pearlfish swim up sea cucumbers’ butts for shelter, every so often several will take up residence in one. Sometimes they’ll eat its gonads, other times they mate inside the sea cucumber. So yeah, [don’t get reincarnated as a sea cucumber](http://stag-mantis.wired.com/2014/02/absurd-creature-of-the-week-pearlfish/).
Gary Cranitch, Queensland Museum03creature-sex-gallery2
Antechinus is a little Australian marsupial whose males go on a three-week, testosterone-fueled sex frenzy. What kind of frenzy? The kind where they have so much sex that they lose their fur, bleed internally, and sometimes go blind. At the end of the three weeks, [every single male has died](http://stag-mantis.wired.com/2014/05/absurd-creature-of-the-week-this-marsupial-has-marathon-sex-until-it-goes-blind-and-drops-dead/), leaving more food for the pregnant females.
D. Parer & E. Parer-Cook/Minden Pictures/Corbis04Paper Nautilus (Argonauta nodosa) on sand bottom, Port Phillip Bay, Victoria, Australia
A female argonaut excretes a beautiful shell from two modified arms. The male isn’t so beautiful. He’s positively tiny compared to her and skips building the shell altogether. When the two meet, he uses his own modified arm called a hectocotylus to transfer sperm into her oviduct. And as he’s leaving, [the arm snaps off](http://stag-mantis.wired.com/2015/01/absurd-creature-of-the-week-argonaut/). Yay for sexual dismemberment!
Image: Current Biology, Yoshizawa et al.05715842
You don’t need me to tell you that boys have boy parts and girls have girl parts. But not for this cave insect. Females have penises that they insert into male vaginas to pick up sperm and a nutritious package called a nuptial gift, which the females are crazy for. Accordingly, [they aggressively pursue males](http://stag-mantis.wired.com/2014/04/scientists-discover-bugs-with-sex-reversed-genitalia-doing-it-for-70-hours/), a rarity in the animal kingdom.
