Do you enjoy a lazy day now and then? Of course you do! Who doesn’t?

We all need to recharge our batteries from time to time. Just don’t get so lazy that people start calling you a sloth!

“Sloth” can be used to describe a person who is physically and emotionally inactive. A slothful person just doesn’t care about anything.

The word “sloth” came from the Greek and Latin words for “carelessness” and “laziness.” In the 1600s, scientists began to use “sloth” as a name for arboreal (tree-dwelling) mammals in the jungles of Central America and South America.

But were they being fair to sloths? Are these animals really lazy?

As it turns out, sloths may be getting a bit of a bad rap. Some may consider them lazy, but others might truthfully believe they’re just really efficient.

Sloths comprise six species of mammals belonging to either the Megalonychidae (two-toed) or Bradypodidae (three-toed) family. Classified this way because of their specialized claws, sloths are related to armadillos and anteaters.

Sloths are “folivores,” which means they eat mostly leaves and buds from trees. Unfortunately, leaves don’t provide much in the way of nutrition or energy.

They also are not easy to digest. Believe it or not, the digestion process in sloths can take a month or more to complete.

Sloths have large stomachs with many special compartments that help break down the tough leaves. At any particular time, two-thirds of a sloth’s weight might consist of what’s in its stomach!

Since leaves provide so little energy, sloths must adapt in several different ways. Not only does their digestion process move very slowly, but their body temperatures are also lower than other mammals their size.

They also conserve energy by spending most of their time hanging upside down in trees. Their specialized curved claws allow them to eat, sleep and even give birth while hanging in trees.

They move only when necessary, and when they do move, they move very slowly. In fact, they move so slowly that sloths are the slowest mammals in the world.

They move so little that algae grow on their fur. Luckily, the algae turn their fur a green color that helps camouflage them among the trees.

Although sloths were once thought to spend up to 18 hours sleeping each day, scientists now believe that sloths usually sleep only 10 hours each day. Are they just being lazy the rest of the day?

Sloths would probably tell you they’re just digesting and conserving what little energy they get from the leaves they eat!


102 Join the Discussion

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  1. Yay, first comment. I cannot believe the amount of research on a sloth. I learned a lot of stuff, and I think tomorrow is about how the mind works. I WONDER why not make a wonder on why we hiccup? Maybe, please use it.

    P.S. What was the first wonder of the day?

    • We thought it was super cool to learn so many new facts about sloths, too, Mak! Now we know why they move so slowly…they’re digesting all those leaves and conserving energy! :-)

    • We thought the baby sloths in the video were super cute, too, Colleen! We think it’s awesome that you can see the resemblance between sloths and anteaters…way to go! Thank you for sharing your comment with us today! :-)

  2. That’s a cute video! Today, I think I’m going to be a sloth. I just want to lay in my bed in my warm blanket because it’s snowing where I am.

    Wonderopolis, can you do a blog about the Illuminati? I would love to see what you guys come up with. Please do a blog about it soon!

    • It’s great to hear from you again, Moises! We think a Wonder about secret clubs and societies, like the Illuminati, would be a great idea! Thank you so much for sharing what types of Wonders you would be interested in seeing in the future! :-)

  3. I was right! I guessed sloths! Yay! I feel smart!!!!!!!!!!!! :D I love sloths. They are just so awesome, and now I know all about them! THANK YOU, WONDEROPOLIS!

    • WAY TO GO, Sharkysharky! You ARE smart (but, we already knew that)! WONDERing makes us want to learn lots of new things, and learning new things only makes us smarter! We hope you have a SUPER AWESOME day! :-)

  4. Dear Wonderopolis,
    I like sloths! I learned a lot! I learned that if someone calls me a sloth, I know it is an insult. NOW I FEEL LIKE HAVING A LAZY DAY!!!!! :) I think sloths aren’t lazy. They just know how to spend their time right. I still WONDER about how they sleep hanging from a tree without falling. Thank you for the WONDER! I bet tomorrow will be about treasure.

    • We think having a lazy day is awesome every once in a while, Nate! Sloths have super strong (and long) toenails (claws) that help them hang from the trees without falling. Thanks for letting us know all the awesome things you learned by exploring today’s Wonder about sloths! :-)

  5. Dear Wonderopolis,
    I learned a lot. I didn’t know that the sloth’s claws were so important. It is very weird that sloths move so slow that algae grows on them. I wonder if they had a faster digestive system, would they be faster? I predict that tomorrow’s wonder is going to be about how our mind helps us solve things.

    Thank you for teaching me about sloths,


    • It sounds like you learned some really interesting things about sloths today, Michael! That makes us really happy to hear! It is super cool that you thought about how the sloth’s speed might be increased if they had a different digestive system. Way to go! :-)

  6. Dear Wonderopolis,

    Thank you for teaching us about sloths. I learned a lot of stuff I didn’t know. Oh, plus, I learned that there is such a thing as folivores, which eat only leaves, and they can give birth while hanging on trees. I wonder if sloths are endangered? I think that tomorrow’s wonder of the day will be about either a jail cell or a monkey.

    Thank you for teaching me about sloths.

    Your reader and number 1 explorer,


    • Hi, Dawson! We’re glad you learned some new things about sloths today! We liked learning what “folivores” means, too! It’s a fun word to say! :-)

  7. Dear Wonderopolis,
    I loved your WONDER of the day. I did not know that sloths sleep so much! They seem very lazy. I wish I could do that sometimes. I did not know that sloths only had 2 claws. I still WONDER how big or small they are? I think tomorrow’s wonder will be about treasure chests.
    From Braeden
    TEAM CAISSE’s 5th grade reading class

    • Hello, Braeden! Thanks so much for leaving us a comment today! We think there are all sizes of sloths, from little baby ones all the way to full-grown adult sloths! What did you think about the fact that it can take up to a month for a sloth to digest one meal! That’s a really long time! :-)

  8. I loved this video. I love your website and it is fun learning new wonders and new facts. This video was really awesome. Thank you for another GREAT WONDER. GOODBYE, WRITE ME BACK.

    • Thanks so much for telling us how much you enjoyed the video for today’s Wonder and that you love visiting Wonderopolis, Dominque! We’re glad you stopped by today! :-)

  9. Dear Wonderopolis,
    I thought learning about sloths was very interesting. I’m surprised that they sleep for 10 hours a day and then they’re lazy for the rest of the day. If I was a sloth, I would have to do something besides sleeping for 10 hours. I didn’t know that sloths are the slowest mammals in the world. I thought it was interesting that the algae covers their fur and makes them camoflauged in the tree. I also didn’t know that sloths are related to armadillos and anteaters. Does the algae come off of the sloths fur, or do they eat it off, or does it stay? I predict that tomorrow’s wonder of the day is going to be about locks. I cant wait to see the wonder of the day tomorrow!!!!!!


    • We’re glad that you can’t wait to visit Wonderopolis again tomorrow, Melina, and we’re really glad you visited us today! We’re not sure what happens to the algae that can grow on some sloth’s fur. We imagine that some of it might get rubbed off as the sloths make their way through the trees. Thanks for sharing all the great things you learned about sloths! :-)

  10. Oh no, I’m allergic to adorableness!

    I’ve always wondered how sloths act, at the zoo they don’t do much. Just kinda hang there and stare at you. Awesome wonder today. :D

    • Your comment gave us a chuckle today, Clayton! We’re sorry you’re allergic to adorable things…there sure were a lot of them in that video! :-)

  11. Dear Wonderopolis,
    Hello! I already knew that sloths were slow, so I feel about 5,000,000 times how sharkysharky feels. I really WONDER…what is the fastest speed a sloth can go? I also WONDER how a sloth can wait a month to digest their food, wouldn’t they die? I predict that the wonder of the day will be about treasure chests! Oh,and I think you should do a wonder about the wonders of the day, but if you do you have to give me credit!
    FROM: Sarah,TEAM CAISSE’s 5th grade reading class

    • Hmmmmm. A Wonder of the Day® about the Wonders of the Day? That sounds like it would be a lot of fun, Sarah! We agree that it was interesting to learn how long it takes for a sloth to digest food. They don’t die because it takes so long, though. Their stomachs and metabolisms are specially made for slow digestion! :-)

  12. Dear Wonderopolis,
    I learned a lot about sloths. I didn’t know that sloths moved so little that algae grew on their fur. I still wonder why sloths are so lazy. I think that tomorrow’s wonder will be about using our brains to help us open, unlock or learn more new things. :)

    Saydi :D

    • We really appreciate all these great guesses you and your Team Caisse classmates are sharing with us about what you think tomorrow’s Wonder of the Day® might be, Saydi! You guys are super smart for using the clues! We’ll all have to meet back here in Wonderopolis tomorrow to see who guessed right! :-)

  13. Dear Wonderopolis,
    I learned a lot about sloths today that I have never known. I did not know that sloths grow algae on themselves. I did not know that
    they had a slow digestive system. I predict that you will make another great subject, like a lock smith.


    • That’s another great guess about tomorrow’s Wonder from the super smart minds of Team Caisse! We like your guess very much, Brandon! Thank you for sharing it with us, and also for telling us some of the things you learned about sloths today! :-)

  14. Dear Wonderopolis,
    Thank you for telling me about the awesome wonder of the day. I already knew that they go so slow. But I did not know that it takes a whole month to digest their food. And it’s so disgusting that they go so slow that algae grows on them and turns them green. I still wonder if their kids stay on that tree, too, or move to another tree? I think tomorrow’s wonder of the day will be about a secret door? From Sydney
    TEAM CAISSE’S 5th grade class

    • Hi, Sydney! We think the baby sloths stay attached to their moms for a good while until they are safe enough to travel by themselves. Then, they probably start exploring other branches of the same trees their moms are hanging from to get comfortable before they “branch” out on their own! :-)

  15. Our class really enjoyed watching the sloth video. We learned that sloths have bad digestion and they can sleep up to 18 hours a day. We were wondering why sloths hang upside down?

    • It’s great to hear from you, Mrs.McKee’s Class! Sloths hang upside down because it helps them conserve energy. We think it would be kind of scary to hang upside down by our toenails, but sloths seem to act like it’s no big deal! Thanks so much for visiting Wonderopolis and for leaving us a comment today! :-)

  16. We love sloths, too! How did you find all of this information, Wonderopolis?? You are amazing.

    We’ve been reading the “wonder of the day” for a week and we’re learning a lot!

    Today we thought the wonder was really cool because sloths are awesome/amazing/totally sloooooooow. :)

    • We really liked receiving your comment today, 5A in Gibbons!!! We WONDER a LOT, that’s how we find such interesting information from many different places and put it all together for each Wonder of the Day®! Thanks so much for letting us know what you thought about today’s Wonder! :-)

  17. Dear Wonderopolis,
    Today’s WONDER of the day was an exciting thing to learn about. I have learned that sloths sleep ten hours a day and spend the rest of the day just being lazy. Ten hours a day is almost half of the whole day! I am still WONDERing if a sloth would do something active instead of sleeping ten hours a day? I predict that tomorrow’s WONDER of the day will be about a famous person who can unlock any type of locks. I got that idea from a t.v show! I can’t wait to see what the WONDER of the day is going to be tomorrow!!!!

    Madison :)

    • Hello, Madison! We know it sounds like sloths sleep a lot and that they’re lazy for the rest of the time, but they are doing what sloths do! What might seem lazy to us might seem very active to a sloth! :-)

  18. Dear Wonderopolis :D
    :D Your wonder of the day was great. I learned a lot I didn’t know. I didn’t know that sloths have growing algae in their fur. I also didn’t know that sloths are the slowest animals in the world. Also, I didn’t think they were that lazy. I think it is just nasty to have algae growing on your fur. I wonder how big sloths are? I also didn’t know that sloths didn’t have a lot of energy. Also I just learned that the word sloth came from the greek and latin words. This was a great wonder of the day.
    Valentena :D

    • Thank you so much for leaving us such an awesome comment today, Valentena! We enjoyed hearing about all the cool sloth facts you learned today! We’re glad you and Team Caisse visited Wonderopolis! :-)

    • Hi, Cassidy! Thanks for wanting to learn more about the sloths in the video! They are all being taken care of at a special “slothspital” in Costa Rica, South America, called the Aviarios Sloth Sanctuary. You can learn more about it here: Have a GREAT day! :-)

    • We don’t know what makes sloths so cute, SINYOR PICONTE, but we’re glad they are! It makes us smile every time we watch the baby sloths in the video for today’s Wonder! :-)

    • We know, Cameron! We thought so, too! We liked the part in the video where the two baby sloths were both chewing on different ends of the same green bean! :-)

    • Thanks so much for telling us how much you liked the video for this Wonder of the Day® about sloths, DJ! We appreciate your comment! :-)

  19. I love sloths, and one of my best friends has a sloth joke while we pay volleyball!! Where can you get a sloth and is it legal to have a sloth in Nebraska???? :))))

    • It’s OK to feel sleepy, lazy and sloth-y every now and again, SINYOR PICONTE! We hope you had a very restful day! :-)

    • We’re so glad to hear that, Asher! It makes us very happy when our Wonder Friends tell us that they WONDER about even more things after they’ve explored a Wonder of the Day®! Keep it up! :-)

  20. Hooray! Another BES class-welcome Mrs. McKee’s class! What a great wonder to start with for your class comment. Isn’t it neat how if you ask Wonderopolis a question-that you get an answer! I love that part about leaving a comment in addition to learning so many new exciting facts! Welcome to the WONDER world!!

  21. I like sloths. Sloths are furry animals. Some have 2 claws and some have 3. They eat green leaves. They loose all their energy and sleep all day.

    • That’s right, Miguel! Thank you for leaving us this AWESOME comment to let us know all the great things you learned about sloths today! :-)

  22. That was a very cute video. We learned that sloths aren’t always lazy. They can have 2 toes or 3 toes. They have curved hands and feet. They are very slow. They can hang upside down for a long time.

    • WOW! Those are some super cool facts you learned about sloths by visiting this Wonder of the Day®, Shelby! Thank you so much for your comment! :-)

  23. I now know that sloths are lazy. How do they lay upside down that long? We could not do that. The video was really cute. I liked it. I love sloths and I have seen them at the Louisville Zoo.

    • We think you are so lucky to have seen sloths at the Louisville Zoo, Kym! What a neat experience for you! We agree that it would be difficult for us humans to hang upside down as long as sloths do, but sloths seem to really enjoy it! :-)

  24. Sloths are not lazy. They are made slow because they eat a lot of vegetables and have no energy. They do what they can.

    • Hello, Jimmy! Thank you so much for sharing what you learned about sloths! We think you are absolutely right…they do what they can! :-)

  25. I like sloths. I am a lot like a sloth to because I love climbing trees and being lazy. I’m good at being lazy. :)


    • A lot of us are pretty good at being lazy every once in a while, SUSHI ROCKS! Climbing trees is super fun, too! Thank you for leaving us a comment today to let us know you visited this Wonder of the Day®! :-)

    • Hello, Jacob! Thank you for telling us what you think about sloths! We’re super glad you visited this Wonder of the Day®! :-)

    • We’re glad you visited Wonderopolis today and learned some new things about an animal you like, Gomo! We think sloths are pretty awesome, too! Thank you for leaving us such a great comment! :-)

    • We think you’re a GREAT Wonder Friend for saying that, “:D!” We really appreciate that you and your TEAM CAISSE classmates visit Wonderopolis each day! :-)

  26. The video was soooo cute!!!!!!! I loved it and Keeley, she was crying. I loved it soooo much. Thank you soooooo much for thinking about this!!!

    • We’re so glad that you liked the cute baby sloth video, Kaylee and Keeley! Thank you both so much for letting us know you visited this Wonder of the Day®! :-)

    • We think they probably do, Kimberlee! Animals in the wild are used to going to the bathroom whenever (and wherever) they need to. It’s part of living in the wild! Thanks for doing some extra WONDERing about this Wonder of the Day®! :-)

  27. Awesome!
    I looked at the funny things about the sloths. The info was funny and the pics of baby sloths were SOOOOOOOOOOOO cute! For school, I have to read a Wonderopolis page and fill out a note card saying: 1. my name 2. the title of the wonder 3. 1 fact I learned 4. my guess for tomorrow’s wonder, and for #3, I’m going to have problems to fill it out. ;) :)

    • We hope you didn’t have any problems filling out #3 on your note card, Ninja Girl! There were LOTS of facts about sloths to choose from in this Wonder of the Day®! Maybe you meant you would have trouble choosing only ONE fact to write down because you learned so many? Thanks so much for visiting Wonderopolis and for leaving us this great comment! :-)

  28. I like when the sloth with the stuffed animal giraffe falls over. Classic! I thought this video was very cute. But, I don’t think sloths are lazy, I just think they move slowly.

    • We liked that baby sloth in the video, too, mazymaemae! It was super cute how it kind of stayed upright for a little while, but then fell over gently, still hugging its stuffed animal. Thanks for stopping by Wonderopolis today and checking out this Wonder! :-)

  29. That’s a cool fact I always thought sloths were just lazy. I never thought it was because the food they eat does not give energy for them to use, so they can’t move as fast or do as much.

    • Hello, Dylan! Thank you SO MUCH for visiting this Wonder about sloths and sharing what you learned with us! We thought it was really cool to learn about why they’re slow, too! :-)

  30. H, wonderopolis. I think sloths are very lazy. A lot of people think they are lazy because they do not move a lot. They look like they’re slow as a turtle. They are very good at climbing trees. I know I cannot climb a tree as good as they can, and I have always been wondering how long it takes them to climb a tree. It would take me 1 hour just to get on a tree. It is so hard for me to get on a tree and my cousin can climb a tree in 10 seconds. My brother can also do it in 10 seconds, but it is a little harder for my brother than my cousin.

    • Thanks so much for sharing your tree-climbing personal connection to this Wonder of the Day®, Kayla! We’re so glad you visited Wonderopolis today! :-)

  31. Hi wonderopolis. I loved today’s wonder of the day and I had a lot of thinking about sloths and you answered a lot of my questions and are you going to do any more sloth wonders? I hope you are, because my whole family loves sloths, and how do you know all this stuff?

    bye, WONDERopolis. Have a fantastic day

    Kayla from mrs.phillips wonderful class

    • We’re glad you were WONDERing a lot about sloths, Kayla! WONDERing leads to learning, and learning makes us SMART! We hope you have a WONDERful day, too…please tell Mrs. Phillips we said, “hello!” :-)

  32. Hi, Wonderopolis! Thanks so much! I’m doing a research report for school on sloths and this really helped a lot. I got a lot of information from this Wonder.

    • We think it’s GREAT that you’re doing a research report on sloths, Loftin! They are WONDERful creatures! Thanks for exploring this Wonder and leaving us a comment to let us know you stopped by! :-)

    • It makes us happy to hear that you learned the real reason why sloths take their time getting from one place to another, Khuong! Thanks for visiting Wonderopolis today and leaving us this SUPER comment! :-)

  33. The sloth video was amazing. I couldn’t stop saying, “Ahh.” I think that you should make a movie about them!!

    • We think all those sloths in the video were super cute, too, Sarah! We admire the special people who help take care of those baby orphaned sloths. It must be a very rewarding job! :-)

    • Thank you for sharing your comment today, Wonder Friend Sloth! Did you learn something new with us today? :)

  34. I love sloths. I have the book for the video. I can name some of the sloths names -Mateo Sammy and Sunshine, “the twins” Buttercup and Sebastian.

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Have you ever wondered…

  • Are sloths lazy?
  • Where do sloths live?
  • What do sloths eat?

Wonder Gallery

sloth_shutterstock_38184406Vimeo Video

Try It Out

Ready for a lazy day? From time to time, we all need a lazy day.

The pressures of the world build up over time, and every once in a while, you just need to set all that aside. What does a lazy day mean to you?

For some people, a lazy day means sleeping in late and then spending the rest of the day on the couch. For others, a lazy day simply means being free from responsibilities, unconstrained by a schedule or just unburdened by things “to do.”

Think about what your perfect “lazy day” would look like. Divide a piece of paper into two columns.

On the left side, write down the things you would do on a lazy day. On the right side, write down the things you would not do on a lazy day.

When you’re finished, email us a copy of your list. We’d love to read what your perfect lazy day looks like!


Still Wondering

Use ReadWriteThink’s Listen, Look, and Learn: An Information-Gathering Process lesson to learn how to do basic research about an animal, like the sloth, after reading a story, such as “Score One for the Sloths.”


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