You’ve probably been through sex ed – or at least know how baby animals are made – so you probably know that it normally involves inserting Tab A into Slot B. But in the animal world, there is more than one way to procreate. Forget what you know about the birds and the bees, because some of these animals procreate by throwing the gender book out the window.

Problematic Relationships: the clingy guy

While having a clingy partner isn’t most people’s idea of a relationship goal, some of you have probably been through one or two sticky partners who were hard to shake off. But what if your partner is way more clingy, like a male deep-sea anglerfish?

You see, when a male deep-sea anglerfish sets his sights on a female (who is much, much larger than he is), he latches onto her and literally becomes part of her – his circulatory system is looped into hers, reducing him to the role of a gonad whose only purpose is to contribute sperm. 

It’s a similar fate for the male Spoonworm, who simply gets sucked into the female’s genital chamber where he becomes something like a slow-release sperm tablet. Interestingly, a Spoonworm larvae has no gender until it lands on the seafloor, where it becomes a female that releases a toxin called bonellin which essentially turns other larvae it touches into males – for sperm duty, naturally.

Perhaps a more lonely male fate is reserved for the mysterious Argonaut octopus, whose sole purpose in life is to pass their sperm – via a detached arm that’s found under its eye – to a passing female, and then he dies.

Female Power: she’s all that

Who says females are the weaker sex? Certainly not the Clownfish! For one, they’re all born as males, and when one of them emerges as the strongest, dominant one… turns into a female and then mates with the other guys! This sex change is call protandry, and the reason the strongest male is tasked with reproduction is because it’s a job suited to only the strongest of the species. Plus, the baby Clownfishes that he produces will be of stellar stock.

In some cases, females don’t even need males to do the job at all. A female Copperhead snake, like some reptiles and sharks, can actually fertilise their own eggs without even needing a male. Unlike hermaphrodites, this ability is called parthenogenesis, and the female snake has the ability to literally give “virgin birth” to live babies (no eggs!).

Boy Meets Girl: when two become one

We all know that hermaphrodites have both sexes within them, and that calls for some pretty bizarre mating-fencing rituals. Snails and their slug cousins are a great example; they both perform a mating ritual that can last hours. When snails mate, they literally shoot each other with their calciferous “love darts” which penetrate the other snail and inject them with hormones. There’s no winner or loser, because the act is mutual: yep, both snails will end up laying eggs. In sea slugs, the dart can be so big that it completely penetrates the body and protrudes out the other side of the recipient! When it comes to the slug world, love really hurts.

On the other end of the size spectrum are polar bears. Some female polar bears in Svalbard, Norway have been found with both male and female sex organs, despite not having the Y chromosome to indicate they’re male. This makes the polar bears pseudo-hermaphrodites, and the reason is heartbreaking: toxic pollutants in the ocean – particularly polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBDE) – can interfere with their hormones, giving them appendages they never asked for.

Penis Envy: the weird appendages

Did you know that with the exception of some ducks, birds don’t actually have penises? They have what’s called cloacas – openings that are either filled with semen or eggs – so they literally bump and grind to procreate. No appendages necessary.

Speaking of appendages, not all of them belong to the males. Take the Neotrogla, for example, which is a type of lice. The females have penises, and the males have the equivalent of a vagina – the weird thing is, she penetrates him… not to deliver sperm, but to collect it.

The Neotrogla isn’t the only female with a male-like extension – the female spotted hyena has a ‘pseudopenis’, which can get up to 7 inches long! The weird part is that it isn’t used to penetrate at all – to mate, the male has to go through her entire shaft with his own penis (in this case, it’s fair to say that size matters). As if that’s not bad enough for her, she later has to give birth through this pseudopenis. 

Speaking of penises, marsupials are a weird bunch – did you know that the appendage of an adorable male echidna has four heads? Most other male marsupials, like possums and wombats, only have… two heads. The reason is simple: female marsupials have two uteri (and kangaroos have 3 vaginas – it’s complicated).  

Blue Balls: precious family jewels

While some of you guys may have heard of the term ‘blue balls’, and even fewer of you have actually experienced it, everyone knows how sensitive a pair of gonads are. There’s a reason nobody sends photos of them to random people.

On the contrary, male monkeys (like vervets and mandrills), love to advertise their dangly bits – because their family jewels are bright blue in colour – by sitting with their legs spread open. It’s a sign of machismo, since the bluer and bigger they are, the more they get swiped right on monkey Tinder. And mothers kick blue-balled juveniles out of their group so they don’t inbreed. 

Turning balls blue isn’t the only way hormones advertise their presence. Anyone who’s owned hamsters, gerbils or other rodents will notice that males will develop enlarged goolies once in a while. Larger goolies create more sperm, because to stand out from the rat pack (and to get his genes passed on), he needs all the help he can get. Even if this means he has to put up with looking like he’s dragging a couple of bowling balls in his sack.

Since we’re on the topic of testes, everyone knows the testosterone within is the reason males develop strong breeding instincts. However, for male semelparous animals, sex is a fatal once-in-a-lifetime affair. For example, the Antechinus (a marsupial) stores a month’s worth of sperm in his gonads and then goes on a breeding rampage until his tank is empty, exhausting him so much that his fur falls off, he bleeds internally, and then he dies. 

At least he gets to keep his body intact; when a male drone bee mates, his explosive ejaculation actually rips his penis off (and then he dies).

Too bad these males don’t have the skills of the Arctic squirrel – thanks to bitterly cold and long winters, they hibernate by stopping the production of testosterone which shrinks their testicles down. However, that means that every March, they have to go through puberty all over again. Hormones can really be a literal pain in the balls.