• Ron Snell

Sloths. Really?


Mama. You can see just one leg of the baby.

To get a feel for a sloth’s life, I wrote this article at my estimated typing speed for a sloth. This means that sloths have undoubtedly evolved quite a lot during the decades of writing, and some of the things I wrote at the beginning are no longer true. I apologize but refuse to start over.


There are a lot of weird things about sloths. Put another way, there’s very little that isn’t weird about sloths. The poor things ended up in a line of evolution that also produced their near relatives the armadillo and the anteater. Then again, sloths would of course evolve slowly, so maybe they are behind everything else. Maybe a million years for any other living thing is more like 10 million years for sloths. Maybe, in fact, they give us a clue as to what life was like at the beginning of life before things had a chance to evolve, kind of like some of the light reaching earth right now started its journey just after the Big Bang. I’m on to something here. Next article: “Sloths, The Only Witnesses to the Origins of the Universe.”


Starting with the basics, there are several species but one of the biggest divisions is between 2-toed sloths and 3-toed sloths. Actually they all have 3 toes, so this distinction isn’t all that helpful except as a wrong one. It’s the fingers that are different, not the toes. “Three fingered sloth” just doesn’t have the same ring to it. Another difference is that 3-toed sloths are diurnal, while 2-toed sloths are nocturnal. For those who can’t keep those straight, we’re diurnal except for my brother-in-law.


Sloths are traveling ecosystems. Each hair is grooved so algae can get a grip, and from there the thick fur becomes home to moths, beetles, cockroaches, and fungi. It’s the algae that makes some of them look so green and provides cool camouflage from eagles, snakes and jaguars, their primary enemies. If you feel like a target in the jungle and you are too slow to get away from predators, dye your hair green. That many sloths can’t be wrong. Oh, and part your hair from the bottom up like sloths do. That hair divide you see on the backs of cows and horses? That’s on the belly of sloths so when they are hanging upside down, which is pretty much always, the rainwater runs off more efficiently.


In the meantime, there’s research going on to determine whether any of that algae might be medicinal. The results are hopeful: In one study of Panamanian sloths, of the fungi collected, 74 types (Yes! There were at least 74 types!) were cultured and subjected to in vitro testing for biological activity against diseases. Three species of fungi were shown to be effective against the human breast cancer strain MCF-7, which is the longest-lived breast cancer strain and is very commonly used in biomedical research. Eight of the fungi tested had high levels of bioactivity against the parasite associated with Chagas disease.


They can take up to a month to digest a leaf as it moves through their four-chambered stomachs being processed by microbial bacteria that they first acquire by nibbling around their mothers’ mouths after birth. That bacterial boost can become a problem too: Two-toed sloths have the lowest and most variable body temperature of any mammal, ranging from 74 to 92 degrees Fahrenheit (24 to 33 degrees Celsius). If there is a long period of cool, rainy weather, a nursing female can get too cold. Since they can’t shiver to warm up (have you ever considered that shivering requires speed?), the cold causes the bacteria in her stomach to stop working, so the mother can no longer digest her food. If she has a baby, it continues to nurse as its mother starves to death on a full stomach. This chilling phenomenon (sorry!) is called cold-weather orphan syndrome.

Digested food is stored in their intestinal tract, then they only poop and pee once a week. That’s the only time they stand upright, it all comes out in one push kind of like having a baby, and they only do it on the ground.


Being a terrestrial pooper is kind of a problem for an arboreal animal. There is that long journey down, the indecent exposure while they are digging a little hole and excreting up to a third of their body weight in one blast, and then the long climb back up at a maximum speed of 6-8 feet per minute if they are lucky enough to have not been eaten. At least they weigh a lot less as they climb.


Biologists have several ideas about why this peculiar habit is beneficial from the “survival of the fittest” perspective. May I just say that I didn’t find any of them very convincing, so I’m not including them here? I mean really, no matter how imaginative you are evolutionarily, what it comes down to is that it would be a lot safer for them to just drop their bombs from high in the trees. There are about a jillion arboreal animals on earth, so it’s a little hard to believe that just one of them figured out that it would be better to wait a week, then climb down to the most dangerous place they could be to do their poo dance. 50% of them die on their bathroom breaks.


In spite of their slowness on land, they are proficient swimmers. They can hold their breath for 40 minutes and go three times as fast in the water as on land. Mind you, that’s not saying a lot compared to crocodile speeds. I read that sometimes in flooded rainforests they drop from a branch into the water to more quickly get from one tree to another by swimming. I think another explanation for it is that they have this insatiable urge to feel what it would be like to do something fast, and falling into water is about as fast as it will ever get, but that just raises another question: if the trees are in water, where and how do they poo? This is what happens when you Google “25 interesting facts about sloths” and you get bullet points instead of a scientific study: The interesting facts don’t always fit together very well. I’m sorry.


If you are the curious sort, you are already wondering how baby sloths ever get made by solitary arboreal parents that move a lot slower than tree sap. So here is one of the greatest of the weird facts about sloths: the one thing they do lightning fast is mate. 5 seconds. Bam! It starts when a female comes into heat and starts screaming in the night. A high pitched scream that lets males know she is wanting the pleasure of their company. Let me just say that when I hear a high pitched scream in the night it has a lot more to do with big spiders or flying horned beetles than anything else.


The males find the source of the screams and if there’s more than one male they fight over her, hanging by their back legs and taking each other on with their front claws. This adds a whole new definition of “fight” to the lexicon. “W-o-w! D-i-d-n’-t s-e-e t-h-a-t o-n-e c-o-m-i-n-g.” After all that, the winner mates in a flash and leaves in what could only be described as slowly. That seems like way too little reward for the complicated logistics of hooking up, but maybe they are onto something here: sloths always seem to be smiling. All of them. All the time.


Depending on the species, gestation is between 7 and 11 months. Sloths are born with long functional claws to an upside down mother high in the trees. Don’t you at least have to wonder how much evolution had to take place before those long claws no longer kept the baby from ever coming out? I mean, the babies grab onto anything close, which would be a hazard in the womb and while exiting but does serve them well as they enter the world hanging onto their mom’s fur for dear life.


“Dear life” is literal. If a baby sloth falls, it most likely won’t hurt itself, but it’s mother usually isn’t inclined to climb down and rescue it because, you know, experience teaches that by the time she gets down there, it will be too late. So it will simply die unless rescued by a well meaning person who will probably kill it with kindness. Raising a baby sloth is best left to the pro’s but here’s a hint for what it’s worth: they like clinging to stuffed animals.


Babies attach to barely visible nipples in their moms’ armpits that produce milk so slowly they are more like leaks. They cling to their moms for several months, learning which leaves are good and which aren’t by tasting bits that are left around their mom’s mouths and as they do so they ingest the particular microorganisms that are necessary to digest the leaves in their stomachs. After a couple years they gain enough confidence to start hanging out on their own, then they end up completely alone in the trees except for the ecosystem that lives in their fur. They can live about 40 years assuming they don’t fall out of a tree or get eaten while on the ground poo dancing.


One explanation for their slowness is a metabolism that barely produces vital signs and a diet of just leaves, leaves, leaves. (Vegetarians take note.) I find this explanation lacking. I mean really, what do giraffes eat? Race horses? Deer? Antelope? Cows? And how many of them take half an hour to get across a road? If leaves were the problem, how come antelope leap across the road in one bound? I’m not saying I know better than the PhD’s. I’m just asking.


Their 4” claws are vice grips, and sloths’ only defense. If you’ve never played with a sloth, here’s a tip: don’t let them get a grip on you. Believe it or not, the grip is so powerful that even dead they can remain hanging upside down from a branch. Puncturing your skin is child’s play. This is the voice of experience. Yes, we played with sloths in Peru a hundred years ago.


As a rule mammals all have seven vertebrae in their necks regardless of whether they are a giraffe, a hamster, or a human. But both sloths and manatees are exceptions. (Manatees? There’s another weird animal. I’m guessing you didn’t know that manatees were declared the national symbol of Costa Rica in July, 2014. No, this isn’t a joke.) Two-toed sloths have 5-7 neck vertebrae while three-toed sloths have 8 or 9. This is why some species of sloths can turn their heads 270 degrees and see almost 360 degrees without moving their bodies, a trait that would make them fantastic security guards if only they could ever get to work on time.


Finally, a little history. Sloths aren’t what they used to be. Some were aquatic and those that were on land varied in size from small to giant sloths the size of elephants. Those big dudes roamed the earth until about 10,000 years ago. Our ancestors ate them. One suspects that they were relatively easy to hunt, right? I mean, it could very well be that hunters drew selfies with them before ambling in for the kill. There was plenty of time.

By now you undoubtedly think I’m an expert on sloths, but you’re wrong. I just pulled together a bunch of information from several sources. Here they are:


http://www.kickassfacts.com/28-fascinating-sloth-facts/ (This is one of the best because it refers to lots of other good sources).

https://www.sciencedaily.com/releases/2011/05/110505212314.htm

https://www.livescience.com/27612-sloths.html

https://sciencing.com/life-cycle-sloths-6758571.html

(To focus on a general topic, just select the category that interests you.)

@2018 by Ron Snell.