If you grew up in the ’90s, you may already be familiar with today’s bizarre beast as it was one of the most obscure animals to ever be featured in a major video game series. If you recall the game Sonic & Knuckles, you’ll remember SEGA introduced a red character named Knuckles—who was, like today’s titular topic, an echidna!

Sadly, real echidnas cannot glide nor punch things with giant gloved hands, and honestly, their love for chaos emeralds is highly overstated; however, actual echidnas are fascinating in their own right.

Echidnas live in Australia and New Guinea and comprise four different species. They are in the order of monotremes, which includes a similarly bizarre beast: the platypus. Like the platypus, they are egg-laying mammals, and while they don’t have a duck-like bill, they do have a long, thin beak which is adapted to prodding around and licking up ants, termites, and other insects.

Typically, with an animal this weird looking—beaky, egg-laying, covered in spines—that would be the end of the article. With the echidna, though, the strange appearance on the outside pales in comparison to what I’m about to talk about: its sex life. Welcome to the first X-rated “Bizarre Beasts,” ladies and gentlemen. Proceed with caution.

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As my motto goes: let’s start with the penis. First of all, it has four heads. Yes, four. Confusingly, the female echidna only has two vaginal openings. While multiple vaginal openings are surprisingly commonplace (the kangaroo has three), this leaves the echidna with a bit of a penile surplus.

In response, two heads of the penis fold up during sex. The next time that male mates, though, he will alternate which penis heads he uses, only ejaculating from two each time. Another oddity: they don’t pee out of their penises. It simply drains out through their cloaca where their penis emerges.

Even behaviorally, echidna sex life is a bit odd. While they are normally solitary, when it’s mating time, males will seek out females. Much to the chagrin of female echidnas, since female echidnas are not always receptive each year, this leads to an overabundance of male echidnas looking for a mate, leading to long “trains” of males. Watch a female lead a train of males in this video from National Geographic:

https://www.youtube.com/watch?v=frZGhk0i228

The males will follow the female and try their luck, mating with the female one after another. Competition is so fierce among males that even their sperm has evolved to be more competitive in order to get a better chance at fathering offspring. Echidna sperm bundles together, making it swim faster as a team than as a solitary sperm!

Competition over females is so intense that in many cases, males try to simply subvert the rules of the game and get a jump on females by mating with them while they are still hibernating. Male competition has driven some males to wake from hibernation a month early and invade the homes of hibernating females. Many females simply awake after hibernation to find out they were impregnated.

That said, new research on echidnas has suggested that females may not be getting as used as one would suspect. It is possible that they are able to store the sperm of multiple males and selectively use it, allowing them to skip the harassment of the mating season, hibernate and then choose their mate post-copulation via their sperm rather than spend time being choosy and losing out on precious rest.

Then, the females can raise their puggles (baby echidnas) after they emerge from their eggs. The puggles are given milk by the mother, but since they don’t have nipples like other mammals, the echidna sort of just… sweats it out and the babies suck what they can from the milk patch area.

Oddly, SEGA decided not to cover these points in their games. Go figure.