What Makes Sloths So Lazy And Slow?

Sloths are probably the ‘spirit animal’ of a sizable chunk of the world’s population… can you guess why?

Because sloths are so damn slow!

Sloths are so notoriously slow that the word ‘sloth’ has actually become synonymous with laziness, lethargy and a general lack of energy. However, have you ever wondered why sloths move so slow? Why do they slog through their lives at such a snail’s pace? Can’t they just hurry up and get moving, and maybe improve their reputation?

What are sloths?

Sloths are arboreal mammals that are known for their general lethargy, and for spending most of their lives hanging upside down in the trees of tropical rainforests.


A sloth hanging upside down. (Image Credit: Pixabay)

Sloths are called arboreal mammals because they move and spend most of their lives in or around trees. The six species of sloths can be easily divided into just two families: three-toed sloths and two-toed sloths. Interestingly, however, all sloths actually have three toes, but two-toed sloths have two fingers or digits on each forelimb.

A sloth can range in size from 24-31 inches (60-80 cm) in length (depending on the species to which it belongs) and weigh anywhere in the range of 3.5-7.7 kg (7.9 to 17.0 lb). Generally speaking, two-toed sloths are slightly larger.
Sloths do have color vision, but their visual activity is not particularly good. Also, their hearing is quite poor. They primarily rely on their senses of touch and smell to locate food and sustain themselves.

Why are sloths so slow?

Sloths are notorious for being exceptionally slow in terms of movement. To help put this in perspective, consider this: on average, sloths travel around 40 yards (36.25 meters) per day. That’s a mere one-third the length of an American football field!


The primary reason why sloths are so slow is that it’s a more efficient way to live! It has a number of other advantages too!

The phrase ‘survival of the fittest’ basically means that the most suitable life forms will survive and reproduce, thus passing down those favorable genetic combinations. There are obvious ‘winner’ species – those that are fast and strong enough to protect themselves from their predators or catch their own prey and thrive. However, natural selection doesn’t just select the fastest and strongest species, but rather those that are most suited to thrive in their environment.

Sloths are one such species that base their ‘strategy’ around maximizing efficiency. First off, they have an incredibly slow metabolism. They move very slowly and maintain a lower body temperature than most other mammals. This means that their need to acquire resources (food) is less than many other animals. It works as a type of trade-off, which is a niche that sloths have mastered.

lazy sloth

Sloths spend most of their time in trees. (Image Credit: Pixabay)

Sloths spend a considerable time of their lives sleeping, and they do so while being well-camouflaged somewhere near the tops of trees. Consider this: every time a herbivore (a creature that only eats plant material) leaves their nest/habitat to look for food, it risks attracting the attention of a predator lurking nearby…. but not sloths!

Sloths have a slow metabolic rate, and their energy needs are much less, so they don’t need to risk going out of their ‘nest’ looking for food. It’s pretty straightforward, actually – less energy requirements translate to fewer risky foraging trips.

sloth costa

Sloths diets consist mostly of leaves which gives them minimal energy and nutrition.(Image Credit: Pixabay)

Sloths are so well camouflaged that it’s very difficult to spot them in their nests. To make things even harder for predators, the sloths don’t even move much. When they do shift, their movement is barely perceptible. Predators are usually alerted by the movement of their prey, so as a predator that relies on motion to spot their prey, you would have a rather hard time spotting a sloth.

All in all, moving slowly requires less energy than moving fast, which is the primary reason why sloths are so slow – it’s just more efficient that way!


  1. Caltech
  2. Michigan State University
  3. University Of Wisconsin–Madison (Link 1)
  4. University Of Wisconsin–Madison (Link 2)
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Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spends a lot of time watching movies, and an awful lot more time discussing them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least.

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