Do the moths in a sloth's fur explain the ground trip?

One 2014 theory says the ground trip serves moths that fertilize algae in the sloth's fur, but the Sloth Conservation Foundation disputes it. The case is still open.

Why Do Sloths Only Poop Once a Week (And Risk Their Lives to Do It on the Ground)?

Q: How much of a sloth's body weight is poop?

A sloth can hold up to a third of its body weight before it finally goes, storing close to 30% of its body mass before the weekly bathroom trip.

Q: What is the sloth poop dance?

A three-toed sloth performs a little wiggle, rubbing its rear against the base of a tree and using its tail to dig a small hole before going.

July 18, 2026

Slow Gains Club I Came I Saw I Sat Down t-shirt featuring the chubby muscular three-toed sloth mascot sitting down

By Slow Gains Club · Field Notes

Somewhere in a Costa Rican rainforest, a sloth is holding it. Has been for days. And when it finally can't wait any longer, it does the single most dangerous thing it will do all week — it climbs down to the ground to poop. Here's why an animal that does almost nothing has turned going to the bathroom into a life-or-death event.

How often do sloths actually poop?

A sloth poops about once a week, and that's it. Some field researchers put the interval anywhere from every three to every eight days, but the headline number the rest of us remember is one bathroom trip per week. For an animal whose whole brand is doing less, this might be the least-often anyone does anything.

And it makes sense once you know their digestion. It can take a sloth a full month to process a single leaf. When your gut runs that slow, there's no such thing as a quick trip. Everything about a sloth is patient, including the part most animals handle daily without a second thought.

Why do sloths climb all the way down to the ground to poop?

A three-toed sloth climbs down from the canopy to the forest floor to poop, which is bizarre because basically every other tree-dwelling mammal just goes from up high and lets gravity sort it out. The sloth instead makes the slow, exposed descent to ground level — the one place it has no defenses at all.

And this is where the joke stops being funny. More than half of all recorded adult sloth deaths happen on or near the ground during these trips, picked off by jaguars, ocelots, and big cats while they're down there doing their business. A sloth on the ground moves at roughly 0.15 miles per hour, which is less "escape" and more "gentle suggestion." Why they take this risk at all is genuinely one of the open questions in sloth biology.

How much of a sloth's body weight is poop?

A sloth can hold up to a third of its body weight in poop before it finally goes. That's not a typo. Because they only unload once a week, it builds up, and researchers at the Sloth Conservation Foundation note sloths can store close to 30% of their body mass down there before the big day.

Put that in human terms and a 180-pound person would be walking around carrying nearly 60 pounds of backlog. The sloth does this calmly, hanging upside down, betraying nothing. Then it climbs down, drops the whole load in one sitting, and walks away visibly lighter. There is no dignified way to describe how much better that must feel.

What is the sloth "poop dance"?

A three-toed sloth performs a little wiggle — nicknamed the "poop dance" — where it rubs its rear against the base of a tree and uses its stubby tail to dig a small hole before going, then covers it up afterward like a tidy housecat. Scientists still aren't fully sure whether the wiggle helps stimulate the bowel movement or does something else entirely.

The descent isn't cheap, either. Climbing down and back up burns around 8% of a sloth's entire daily energy budget, which is a lot for an animal that runs on a near-empty tank of fermented leaves. So this isn't a casual stroll. It's a scheduled, effortful, weekly expedition, and the sloth commits to the whole routine every single time.

Do the moths living in a sloth's fur explain the whole thing?

A colony of moths lives in a sloth's fur, and one leading theory says the ground trip exists to serve them — which is exactly where scientists start arguing. A 2014 study in Proceedings of the Royal Society B by Pauli and colleagues proposed a tidy loop: the sloth climbs down, the moths hop off to lay eggs in the fresh dung, and in return they help fertilize nutritious algae growing in the sloth's coat, giving it an energy boost.

But the Sloth Conservation Foundation pushes back hard, arguing the sloth gets little real benefit and the math on that algae payoff doesn't hold up. Others think it's simpler — that ground latrines are how sloths leave a scent note so mates can find each other. Nobody has closed the case. An animal this slow has quietly held onto a mystery that faster, flashier creatures never managed to keep.

So here's the takeaway from the world's least-hurried mammal: it holds it for a week, makes one deliberate trip, sits all the way down, and handles the most important business of its life without rushing a single second of it. We put that energy on a shirt — I Came, I Saw, I Sat Down. The sloth would approve, right after its nap.

See the “I Came, I Saw, I Sat Down” shirt →