Self-castrating spiders

Do you fear for your life during pairing? Maybe not if you're a human, but for the male spider Nephilengys malabarensis, there's a 75% chance that he will fall victim to a females' penchant for cannibalism during sex. Unfortunately, this can also mean that the male may be killed before he has dispensed all his sperm, and to make matters worse (given the circumstances), his chances of fathering the next generation may be displaced by the sperm of the next successful male snack - er, suitor.

Male: "I didn't choose this life"

The address to this problem? The male snaps off his penis inside his partner while they have sex. Without his bulky sperm pump, the newly-lightened male can now fend off other males wanting to mate with his partner for longer without tiring, with an increase in stamina of up to 80%! And while defending his female, his detached genitals continue to pump sperm into the female.