Sloth mystery solved: How moths and algae shape this unusual creature's toilet habits

Why sloths descend from the safety of the trees once a week to go to the toilet has baffled scientists - but one specialist thinks he has the answer

Sloths’ toilet habits have long confused biologists. Although this enigmatic tree-dweller is famously slow-moving (they climb at a maximum speed of around eight feet per minute) they're still pretty safe from predators as long as they stay in the tree tops.

Yet once a week (they have very slow metabolisms – that’s what eating only leaves does to you) sloths will descend from the safety of the canopies for a toilet break on the forest floor. Doing so makes them incredibly vulnerable to predators and yet they persist - with many even having favourite trees that they will return to again and again when nature calls.

Biologists have offered a number of explanations (could they be fertilizing a favourite tree? Are they picking up minerals from the soil to supplement their diet?) but none have quite held water. Now, one specialist thinks he might have the answer, and oddly enough it’s as much about moths as it is about sloths.

These baby sloths are pretty clean - but out in the wild sloths' fur is home to algae and insects. Jonathan Pauli, an assistant professor at the University of Wisconsin, Madison, first got interested in the sloth poo mystery after watching a video on YouTube from a David Attenborough documentary named “Mouldy Sloth”.

In the video Attenborough describes how the sloth has developed an unusual system of camouflage by letting its fur become infused with algae. In the rainy season these “algae gardens” turns green to match the lush jungle vegetation, and in the dry season they fade in colour along with the plants.

This creates a miniature ecosystem in the sloth’s fur, and alongside the plant life there are also plenty of moths present. In some cases, biologists have found up to 120 specimens living on a single sloth ("Imagine an infestation in a shag pile carpet on top of a compost heap,” says Attenborough) but it’s these insects that Pauli thinks holds the key to the sloth’s odd toilet habits.

Sloths only need to go to the toilet once a week because of their low-energy diet and slow metabolism. Whilst studying three-toed sloths in their native habitat in San José, Costa Rica, Pauli observed how these moths would hop off the animal went it went to the loo and lay their eggs in the sloth’s dung. When these eggs hatched the moths would then fly back into the sloth’s fur, and the whole cycle would start again.

Most importantly, when the insects die and decompose in the sloths fur they provide essential nutrients that encourage the growth of the algae. Pauli tested various hair samples from different sloths and found that the more moths on the animal the more ammonium - a key fertilizer - was present in their fur.

So, by choosing to defectae on the floor rather than from the trees, the sloths could be encouraging the moths' lifecycle which in turn helps the alge grow. Not only does this algae provide the sloths with camouflage, but it’s also been theorized that the animals eat the stuff when grooming one another.

It may sound an unappetizing meal but the extra minerals, fat, and calories in the plant life could be vital in supplementing sloths' strictly vegan diet. Pauli's theory has yet to be completely proven, but it offers one of the best explanations for this peculiar and charming animal's mysterious toilet habits.

Start your day with The Independent, sign up for daily news emails
PROMOTED VIDEO
ebooks
ebooksA year of political gossip, levity and intrigue from the sharpest pen in Westminster
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Account Manager

£20000 - £35000 per annum: Recruitment Genius: This full service social media ...

Recruitment Genius: Data Analyst - Online Marketing

£24000 - £35000 per annum: Recruitment Genius: We are 'Changemakers in retail'...

Austen Lloyd: Senior Residential Conveyancer

Very Competitive: Austen Lloyd: Senior Conveyancer - South West We are see...

Austen Lloyd: Residential / Commercial Property Solicitor

Excellent Salary: Austen Lloyd: DORSET MARKET TOWN - SENIOR PROPERTY SOLICITOR...

Day In a Page

Isis in Iraq: Yazidi girls killing themselves to escape rape and imprisonment by militants

'Jilan killed herself in the bathroom. She cut her wrists and hanged herself'

Yazidi girls killing themselves to escape rape and imprisonment
Ed Balls interview: 'If I think about the deficit when I'm playing the piano, it all goes wrong'

Ed Balls interview

'If I think about the deficit when I'm playing the piano, it all goes wrong'
He's behind you, dude!

US stars in UK panto

From David Hasselhoff to Jerry Hall
Grace Dent's Christmas Quiz: What are you – a festive curmudgeon or top of the tree?

Grace Dent's Christmas Quiz

What are you – a festive curmudgeon or top of the tree?
Nasa planning to build cloud cities in airships above Venus

Nasa planning to build cloud cities in airships above Venus

Planet’s surface is inhospitable to humans but 30 miles above it is almost perfect
Surrounded by high-rise flats is a little house filled with Lebanon’s history - clocks, rifles, frogmen’s uniforms and colonial helmets

Clocks, rifles, swords, frogmen’s uniforms

Surrounded by high-rise flats is a little house filled with Lebanon’s history
Return to Gaza: Four months on, the wounds left by Israel's bombardment have not yet healed

Four months after the bombardment, Gaza’s wounds are yet to heal

Kim Sengupta is reunited with a man whose plight mirrors the suffering of the Palestinian people
Gastric surgery: Is it really the answer to the UK's obesity epidemic?

Is gastric surgery really the answer to the UK's obesity epidemic?

Critics argue that it’s crazy to operate on healthy people just to stop them eating
Homeless Veterans appeal: Christmas charity auction Part 2 - now LIVE

Homeless Veterans appeal: Christmas charity auction

Bid on original art, or trips of a lifetime to Africa or the 'Corrie' set, and help Homeless Veterans
Pantomime rings the changes to welcome autistic theatre-goers

Autism-friendly theatre

Pantomime leads the pack in quest to welcome all
The week Hollywood got scared and had to grow up a bit

The week Hollywood got scared and had to grow up a bit

Sony suffered a chorus of disapproval after it withdrew 'The Interview', but it's not too late for it to take a stand, says Joan Smith
From Widow Twankey to Mother Goose, how do the men who play panto dames get themselves ready for the performance of a lifetime?

Panto dames: before and after

From Widow Twankey to Mother Goose, how do the men who play panto dames get themselves ready for the performance of a lifetime?
Thirties murder mystery novel is surprise runaway Christmas hit

Thirties murder mystery novel is surprise runaway Christmas hit

Booksellers say readers are turning away from dark modern thrillers and back to the golden age of crime writing
Anne-Marie Huby: 'Charities deserve the best,' says founder of JustGiving

Anne-Marie Huby: 'Charities deserve the best'

Ten million of us have used the JustGiving website to donate to good causes. Its co-founder says that being dynamic is as important as being kind
The botanist who hunts for giant trees at Kew Gardens

The man who hunts giants

A Kew Gardens botanist has found 25 new large tree species - and he's sure there are more out there