If you think penguins are adorable, don't be fooled - they're baby-snatching, home-wrecking monsters, and they can absolutely ruin your day by trying to gouge each other's eyes out during a marital spat.

Case in point: new footage shot by National Geographic, featuring an incredibly bloody male-on-male fight between a jilted mate and his rival. The ending is so real, it's like holding a mirror up to humanity itself - and the internet is not happy about it.

In the clip below, we're introduced to a 200,000-strong colony of Magellanic penguins, which gather on Argentina's Punta Tombo peninsula for the breeding season in September.

Nests and burrows will be built, eggs will be laid, and chicks are expected to start hatching this month. 

And while many Magellanic penguins form lifelong mating pairs - one couple has reportedly been together for a whopping 16 years - not every female is interested in staying with the same male for her entire breeding life.

Nope, the reason this fight breaks out at all is because a male returns to his burrow to find his mate has paired with a different male.

The fight breaks out between the pair of males over a single female, and things escalate quickly as they begin to club each other with their flippers at a rate of eight blows per second. 

As the narrator explains, most birds contain hollow bones in their wings to make them more aerodynamic, but because penguins can't fly, they have solid bones in their flippers. That means a whack from a penguin can deliver a serious clobbering - especially if you happen to be just 76 cm tall (30 inches).

While thick, insulating blubber ensures that the penguins' vital organs are more or less protected, they can easily open up superficial wounds, and beaks ordinarily used for digging burrows are trained in on the opponent's eyes.

Things start out bad for the jilted male, and only get worse. The fight stops temporarily as the two males reach a stalemate, and call out to the female to choose between them. She doesn't even hesitate to choose the 'homewrecker'.

Her original partner doesn't accept her choice, and the fight continues after he drags his rival out of what was once his own burrow.

Things get even more bloody before the 'husband' realises he has to give up, and the narrator really twists the knife by declaring, "There's no room for losers." Jeez.

In what could be the most heartbreaking moment of all, the defeated male must now run away and lick his wounds, but not before tripping over a branch in front of his cheating ex-partner. The world weeps with you, little penguin. You are all of us.

The good news is that, with a 200,000-strong colony to mingle with, he'll hopefully have the chance to find another mate once he's all healed up.

While this footage is in no way an easy watch (and yes, the narration is a bit much at times), it's an important reminder that just because animals look cute to us, nature is brutal, and wild animals very rarely die of old age. 

But then sometimes there are little penguins called Cookie that have 'bumblefoot' and have to wear socks, and sometimes they really like tickles, and suddenly everything is alright with the world: