14 Days of Genitals, Day 12: Traumatic Insemination

Trigger warning on this one - Bed Bugs are NOT nice to each other. 
Bed bugs have never been all that appreciated by humans and that's probably gonna continue after you read the following. Bed bugs, specifically Cimex lectularius, have a special little mating adaptation called Traumatic Insemination, which is about as clear a scientific term as there ever was.

The most painful piercing ever

14 Days of Genitals, Day 12: Arms Race Between the Sexes

Survival of the fittest doesn't always mean survival of the nicest. Sometimes assholes are the best at reproducing, and water striders are really, really good at reproducing. 

Not the biggest asshole in the animal kingdom (wait 'til day 14), but close.