When someone is very lazy or slow, we call them slothful. That's because sloths spend up to 20 hours a day sleeping. And when they are awake, they barely move at all! In fact, they stay still so much that green algae grows on their fur and moths live in it!

They look a little like monkeys, with long arms and shaggy fur. But actually, sloths are related to anteaters!

Sloths are not a danger to people, but like most wild animals, they like to be left alone. Some people like to pick them up, because they are so gentle. However, if they feel afraid, they may fight back. Sloths have long, sharp teeth and claws to defend themselves against people and predators such as hawks or cats.

There are about 1,500 sloths left in the wild. They are in danger due to deforestation or destruction of their habitat.

slothful: lazy, slow

algae: small, green living things that look like plants, ex) seaweed

moths: night-flying insects that look like butterflies

are related to: connected to, are relatives

deforestation: the cutting down of forests

Sloths are 2-2.5 feet (0.6-0.8m) long and weigh from 8-17 pounds (3.6-7.7 kg). That's about the size of a small dog. They live for 20-30 years.

There are two main types of sloth, two-toed sloths and three-toed sloths. They all have very long, sharp claws! Sloths have small round heads, small eyes, tiny ears and short tails. They have large noses and small mouths that look like they are smiling. 

Two-toed sloths are nocturnal and spend most of the time hanging upside-down in the trees. Three-toed sloths are a bit bigger and sometimes sit upright. Hanging upside-down doesn't take any energy. They can lock their feet and claws around tree branches and don't need to hold on. They can even sleep without falling.

Sloths are very slow to move on land. They don't run and they don't jump. They drag themselves slowly along the ground at about 1 foot (30cm) each minute. They can't even move fast if a predator attacks them. However, they are very good swimmers! They can swim 3 times faster than they move on land. They also have extra bones in their necks so that they can turn their heads most of the way around and keep their noses above water!

They may not be fast, but sloths are surprisingly strong. They are about 3 times stronger than a person. This is because their arms and legs need to be strong to hold onto trees.

nocturnal: awake at night

lock: close, not let go, not open

drag: to pull along the ground

predator: animal that eats other animals

Sloths are herbivores. They like to eat leaves, twigs and buds. Because they move so slowly, they don't need to eat very much. However, the leave they eat are very difficult to digest. It can take days or even weeks for them to digest a meal!

Mother sloths have one baby each year. Babies are called pups. A sloth baby has lots of fur, its eyes are open and it is able to climb. It holds onto its mother and drinks her milk for the first few months of life. After 2-3 months, it starts to eat leaves and at 6 months of age, it can live on its own.