Immediately after sexual intercourse, a female praying mantis will rotate her head 180° and eat the head of the male. Therefore male praying mantis has an extra “brain” in its rear, which controls the necessary motions for copulation, so it can continue mating after the female has eaten his head.
The male mice have a tendency to woo the female by directing their urine in the female’s direction. Their urine contains pheromones and if a pregnant female rat is exposed to the scent of an unfamiliar male, she will automatically abort her child if she has conceived one. This phenomenon is called 'The Bruce effect'.
Oxpeckers, the small birds you see in photos perching on antelopes and wildebeests (elephants shake them off usually), were once thought to be helping these animals by eating illness-causing ticks. It was later found that these birds open wounds wider and drink the blood of their hosts, so they're parasites themselves.
34Emerald Cockroach Wasp
The Emerald Cockroach Wasp is a parasite. First, it stings its host, the cockroach in the thorax to paralyze it. Then, the second sting goes to the roach's brain to a precise spot to more permanently and thoroughly paralyze it. Then, the wasp leads the roach back to the wasp's burrow by tugging its antennae like a leash. The roach can't initiate walking on its own, because of the venom, but the actual neuromuscular circuitry that physically controls the legs is just fine, so a little tug from the wasp and the zombified cockroach follows its new master to its doom. There the wasp lays an egg in its abdomen, then its larva eats the organs in a specific way to keep the roach alive before it cocoons and leaves its body.
The green-eyed wasp turns ladybugs into zombie babysitters. Three weeks after a wasp lays its egg inside the hapless beetle, a wasp larva bursts from her belly and weaves itself into a cocoon between her legs. The ladybug doesn’t die but becomes paralyzed, involuntarily twitching her spotted red carapace to ward off predators until the adult wasp emerges a week later. Researchers have found that the wasp uses a virus to attacks the beetle’s brain.
While mating, hermaphroditic species of flatworms engage in penis fencing, battling violently to decide which of the two will be the father. The winner stabs his penis into the loser to inseminate it.
The Orange Clown Fish family consists of several males living with a female, which is the largest fish in the group. She harasses her female offsprings and denies them access to food to control their size to deter sexual competition. The largest male exclusively reproduces with the largest female until she dies. Then, the largest male develops female reproductive organs, turns into a female and the next largest male becomes the breeding male.
Koalas have a scent gland on their chest that they use to mark their territory by aggressively hugging trees. At the culmination of the violent tantrum which is koala coitus, the male leaves a seminal plug which blocks the female's multiple vaginas from being entered by the hemipenis of another koala. Female koalas are also infamous for engaging in lesbian sex. Females often overlook males and participate in sexual acts with other females, sometimes in orgies with up to 5 female koalas. Also, koalas are riddled with chlamydia.
Beaver’s teeth are orange because they are fortified with iron which makes them strong and cavity-resistant. Their teeth also continuously grow and self-sharpen, which is why they are always chewing on wood.
Honey bees initially have up to 21 virgin queen bees, who fight to the death until there is only one left. Then when male honeybees mate with the queen, their penises explode (which is audible to the human ear) and they die. During the queen's nuptial flight, she'll mate with about a dozen partners and leave a trail of dead, penisless bees in her wake.