Pale-Throated Sloth vs Frilled Shark vs Giraffe Weevil vs Immortal Jellyfish: A Mammal That Poops Once a Week and Might Die Doing It, a Dinosaur Eel With 300 Trident Teeth, a Bug Built Like a Construction Crane, and a Rice Grain That Refuses to Die

I love comparing things that have no business being compared, and today I have outdone myself. In this corner: a mammal so slow it grows its own salad, that leaves the safety of the canopy once a week purely to go to the bathroom, and frequently dies for the privilege. In the other corners: a shark that has been coasting on the same design since the dinosaurs, a beetle wearing its neck like scaffolding, and a jellyfish the size of a booger that has solved death and is very smug about it. I judge on three things and three things only: how **cool**, how **weird**, and how **gross**. Then I pick a winner, because a comparison without a verdict is just a list, and lists are for people who alphabetize their spices. Let's go.

The contestants, ranked by how much they alarm me

Before we score anything, understand the spread here. We have four animals from four completely different branches of the tree of life who would never meet, could never meet, and if they did meet would have absolutely nothing to talk about. This is my favorite kind of matchup. Nobody has home-field advantage when the field is the entire concept of biology.

The Pale-Throated Sloth: a mammal that is also a compost heap

Let me get you up to speed on the sloth's whole situation, because it is unhinged. This animal moves so slowly that green algae grows in its fur. That algae supports a colony of moths that live ON the sloth. The moths lay eggs in sloth poop, the larvae eat the poop, the adults fly back up into the fur, they die, they fertilize the algae, and the algae feeds the sloth. The sloth is not an animal. The sloth is a studio apartment with a heartbeat.

And here is the part that keeps me up at night. To keep this whole ecosystem running, the sloth climbs all the way down to the forest floor about once a week to poop, instead of just dropping it from a branch like a reasonable arboreal creature. This trip is so dangerous that researchers found more than half of documented sloth deaths happened during these bathroom breaks. The sloth is out here dying for its gut. That is either the dumbest or the most committed thing in this entire post, and I have not decided which.

Mechanically it is a marvel: nine neck vertebrae (most mammals have seven) let it swivel its head about 270 degrees, its tendons work like coat hangers so hanging upside down costs it almost no energy, and it is roughly three times stronger than you despite having about 30 percent less muscle. It also swims about three times faster than it walks, which tells you everything about how fast it walks. A single leaf can take up to a month to digest. This animal experiences time differently than we do.

The Frilled Shark: a lizard with a subscription to the Cretaceous

The frilled shark has looked basically the same for around 80 million years, which is the biological equivalent of never updating your phone and being smug about it. It is eel-shaped, up to about 2 meters long, and lives down in the deep dark where you would need a submarine and a bad reason to find it.

The mouth is the headline. Around 300 teeth arranged in roughly 25 rows, and each tooth is a tiny backward-pointing trident with three prongs. The whole apparatus is designed so that once a squid goes in, it does not come back out. It is thought to strike by coiling and lunging forward like a snake, a move no other shark family is known to pull, although nobody has actually watched it happen in the wild because it has the social schedule of a hermit. The name comes from six pairs of frilly, fringed gill slits at its throat (most sharks have five), the first pair wrapping around like a collar. And the truly absurd stat: its pregnancy may run about 3.5 years, possibly the longest of any vertebrate, which laps an elephant nearly twice over.

The Giraffe Weevil: a beetle that brought scaffolding to a bug fight

Over in Madagascar, where all the good weird lives, there is a 25mm beetle with bright berry-red wing cases and a neck situation that has to be seen to be believed. The males have necks two to three times longer than the females, and they use them exactly how you would hope: to push, lean, flip, and shove rival males around, like tiny rutting deer that also happen to be beetles.

The female's neck is shorter but arguably more impressive in application. When it is time to lay her single, precious egg, she uses her neck like a lever and an awl to roll a leaf into a tight little tube, wrap it, and snip it off as a cradle. One egg. One handmade leaf burrito. This is the only animal in today's lineup with a craft hobby.

The Immortal Jellyfish: a booger that beat death and won't shut up about it

And finally, the reigning champion of not dying. Turritopsis dohrnii is about 4.5mm across, transparent, with a bright red cross-shaped stomach you can see right through its body. It looks like something you would rinse out of a swim mask. It is also, functionally, immortal.

When this thing gets stressed, starved, or injured, it does not die. It melts back down into a blob and turns back into a polyp, which is its own baby stage. A butterfly turning back into a caterpillar. And it can, in theory, do this over and over forever. The cheat code is real. The catch, and I say this with enormous satisfaction, is that in the actual ocean most of them still get eaten or catch a disease before they ever pull the ripcord. So it has beaten aging but not lunch. It has also colonized the entire planet, probably by hitchhiking in the ballast water of ships, which is a very cool way for a booger to see the world.