Who doesn’t love sloths? They’re furry, cute creatures that are not only adorable but extra chill. Sloths are having a moment in 2019, as they are showing up in GIFs, videos and memes.
We’d like to join in the sloth appreciation movement by taking a closer look at the appealing animals and asking some questions that might trouble us from an evolutionary and scientific perspective. To wit: why do sloths move so slowly? How can this be an evolutionary advantage? And why don’t predators decimate them?
Just How Slow Are Sloths?
Let’s start with the basics. We know that sloths are slow, but just how slow?
Sloths are the slowest mammals on earth. They generally move only about 125 feet per day and have a normal top speed of .o6 miles per hour.
Sloth also sleep a LOT. Sloths spend about half their day asleep, and in captivity, they’ve been known to sleep for 16 to 20 hours a day. All that napping means that they don’t move very much. In Spanish, sloths are called osos perezosos or “lazy bears.”
But WHY Are They So Slow?
The first reason is that sloths are vegetarians. Their diet won’t support a lot of calorie burning. A fully vegetarian diet does not provide them with calorie-dense intake, and moving fast always burns more calories.
In addition to the limits of their completely vegetarian diet, sloths just don’t eat a great deal. Since they spend so much time sleeping, they actually don’t take in as many calories as other herbivores.
Let’s compare them to another tree-dwelling herbivore, the koala. Koalas eat almost a pound of food a day in leaves and twigs. This is how much a 25-pound animal needs to provide the energy to move around. Sloths eat much less and therefore need to conserve energy.
If we consider the low-calorie diet, the low intake of calories and the long naps, this can add up to a sloth just not moving much. Another characteristic that leads to slothful slowness, however, is their metabolism.
Sloths, unlike other arboreal animals, have very slow digestive systems and metabolisms. It takes sloths a very long time to digest their food. At any given time, something like two-thirds of their body weight is made up of undigested food in their digestive tract. Just imagine if you were carrying 50 pounds of food in your stomach! You’d be slow too!
All of the above explains how and why sloths have adjusted to a minimal effort, minimal energy way of life.
So How Do Sloths Survive Predators?
Since sloths have such a low top speed, it’s obvious that they aren’t going to outrun any other animal that wants to eat them. They seem like they would be sitting ducks and an easy meal. So how do they survive?
Camouflage is one way. Sloths live in rainforests and jungles, very humid environments. Because of this, a layer of green algae develops on their fur, creating the perfect blend of green and brown. This color pattern works wonderfully to hide sloths from predators. Often, a sloth will blend in perfectly with the branches and leaves around them, and they are nearly invisible.
A sloth’s claws also help protect it. The claws on the end of a sloth’s paws are designed to help it grip the branches of the trees where it lives, but they also provide a measure of protection against predators. A swipe from those long, curved nails can cause a lot of damage.
Finally, stubbornness is another reason that sloths make poor prey for birds, jaguars or humans. Even after they are shot or killed, their paws and claws do not let go of their trees. They remain fixed to where they were, making it harder for a predator to take them home for dinner.
Cute Faces, Enviable Lifestyle
Sloths have become a favorite animal of many, with big eyes and a face that looks like they are smiling. In addition to being cute, too, they have what many of us see as an enviable lifestyle- munching contentedly on delicious vegetables and napping nearly all day long!
Go visit your local zoo or take a trip to the rainforest to check out this slow-moving creature!