It sounds crazy, but suicidal reproduction - also known as semelparity - is common in nature. There are a surprising number of animals that immediately die after having sex or not long after the mating season. The males especially are forced to live fast and die really, really young - often only surviving for about a year.
Why is this a thing? Scientists aren't 100 percent sure, but it could have something to do with adaptation and survival. Males that die right after mating aren't sticking around to eat all the food and take up space. Another theory? It's just a freak thing: a "quirk" of nature that locks these poor creatures in a hellish cycle. Regardless of the exact reason, there are some really fascinating facts about animals that die after sex.
Furcifer Labordi Chameleons mate in January, "a nasty, often violent business of males fighting males, females fighting males, and all of them wishing they were somewhere else," according to Natalie Angier, writing for the New York Times. If they don't kill each other while trying to mate, hormone overdoses due to high levels of aggression might kill them. Regardless, the males and females both die after successfully mating and laying eggs, and then just "drop from the trees with the papery grace of autumn leaves." This particular species of chameleon spends two-thirds of it existence as an egg buried in the sand and "16 to 20 weeks" post-shell, its entire lifespan over in barely a year.
The males in all 12 species of the marsupial mammal antechinus die after their first time successfully breeding, typically from stressing themselves out. Seriously: the stress of the breeding season destroys their immune system, leading to liver infections and parasites of the blood and intestine. While some females live to breed for another season, all the males are sure to die. That's not the only place males get the short end of the stick: as babies they're denied adequate milk by their mothers, who prefer to wean the females. At least they get to end their pathetic, year-long lives trying to mate with as many females as they can, "in violent, frenetic encounters that can each last up to 14 hours."
Some female praying mantises bite their much smaller mate's head off after or even during fertilization. That's cold-blooded, for sure, but to make matters worse, the poor sap gets seduced by pheromones and a courtship dance beforehand. What's the advantage of biting your mate's head clean off like it's a Teddy Graham? Believe it or not, research shows "the male appears to thrust more vigorously" once beheaded and the cannibalism may lead to more successful mating.
Unlike the mammals and lizards on this list who get sick or just die of natural causes after mating, male Australian Redback Spiders commit sexual suicide. Like their American cousin the black widow spider female Redbacks devour males post-coitus if they make themselves available. Males who choose to sacrifice themselves "sire proportionately more offspring than do the partners that the female spiders choose not to chew." That's not the only motivation: a male Redback's lifespan is so woefully short, he will likely die or get eaten by a predator before making it to another female's web anyway, so why not take the plunge?