Critters give new meaning to unsafe sex

Small flies of the family Anthomyiidae getting down and dirty. (André Karwath/Wikimedia Creative Commons)

If you thought you liked it rough, think again. Nature has got you beat. Beyond the squeaky bed and the slippery kitchen countertop, insects punch holes into their mates, spiders bite gashes in their partners and cuddly innocent-looking Australian marsupials have sex franticly until they literally drop dead. 

Take, for example, dragonflies. Males of the most violent species put two to six holes, on average, in the female's heads as they grasp their mate in copulation. Males from a less violent species gouge part of the female's eye. It’s common to see splits in the exoskeleton of permanently disfigured females after they have mated.  

Some may have heard about bed bug sex: males violently penetrate the body wall of a female and inject their sperm in hopes that it will contact an egg. This is referred to as traumatic insemination and it doesn’t just happen in insects. A male Israeli spider discovered in 2009 courts a female with a dance, digs his fangs into her, embraces her, pierces into her body with his reproductive organ and ejaculates. He does this six times throughout the female body, leaving visible wounds to which the female tends afterward. 

If you were a marsupial called antechinus in Australia, you’d skip courtship all together. For antechinus, the coming of spring signals a cascade of potent hormones that absolutely drive males crazy. For almost three weeks, males franticly have sex with any antechinus female they can find, often by forceful and violent means, moving from one to the next. They become so obsessed with having sex that they bleed internally and often lose their eyesight. Eventually, all the males die and the females are left to take care of the offspring. Of course, the death of the males is actually in the best interest of the offspring- without males, there’s more food available.

It may seem like horror and cruelties abound in the wild, but there’s reasoning to all the madness. 

Sex creates all of the diverse beauty and variety we see across the world today. Because of sex, offspring are variable. They receive a mixed set of genetic information from both parents and different combinations of genes create differences in offspring. Once there are differences, natural selection swoops in and drives changes that create new species and ecosystems. Offspring that aren’t great at surviving and reproducing disappear along with their genes, while offspring that are good at surviving and reproducing pass on their genes to future generations. In this way, sex allows life to thrive and diversify.

In the opposite scenario, a living thing would have to clone itself instead of having sex. If it were to have genes unsuited for survival and reproduction, it would die and disappear along with all of its genetically identical clones. 

For these reasons, sex dominates all life, but the benefits of mating don’t necessarily mean civility between males and females in the wild. There’s an evolutionary tug-of-war between the sexes, which is not surprising when you really think about it.

Females, unlike males, must carry the burden of producing energetically expensive eggs and offspring, making females much more selective when it comes to sex than males. Since sperm is relatively easy to make continuously, males are much less selective, but often have dramatic traits to court selective females. 

When you see male birds flying around with colorful plumage during mating season, you can be sure that it's a product of sex. On the other hand, males of other animals take unimaginably violent means of mating and the examples above are but a tiny glimpse into the gruesome, but fascinating, sex lives of unexpected critters.


Diler Haji is a staff writer for The Daily Campus. He can be reached via email at diler.haji@uconn.edu.