Sloths are slow! REAL SLOW! Lazy people are even referred to as sloths here in the states. So, why are they so slow?
On average, sloths travel less than 50 yards per day. That’s less than half the length of a football field! Sloths are the slowest moving mammal on the planet. Being slow is a very effective survival strategy for sloths. They have survived for at least 60 million years being slow. In order to understand why this is, we have to look at the biology of the sloth.
The first piece of the puzzle is their low-calorie folivorous (mostly leaves) diet. Many other folivorous animals move at a normal pace, so this doesn’t explain much by itself. The difference lies in the sloth’s slow rate of digestion.
Digestion rate scales with body size in most mammals, meaning larger animals will take longer to digest food than smaller ones. Sloths don’t adhere to this rule. The exact rate of digestion isn’t clear, but current estimates range all the way from 6 days to 50 days. This means it takes between 6 and 50 days for sloths to pass food once they have consumed it. Most folivores compensate for a low-calorie, leaf-based diet by consuming large amounts of food. Sloths can’t do this because they digest food so slowly. Because of this, sloths have very little extra energy at their disposal. Imagine how you’d feel if you ate your dinner tonight and couldn’t eat again for between 6 and 50 days. This means that sloths are likely surviving on the very edge of their energy budget, and everything they do has to be constantly geared towards conserving energy. Moving slowly requires a lot less energy than moving fast, so sloths move so slowly to survive.