It seems like sloths are “spiritual animals” to many people around the world. They eat, sleep, hang in the trees all day long, and mind their business without worry. At least that is how it looks.

Turns out, there are a number of reasons why sloths are so slow, and laziness is not one of them. Here are some things you should know about the slowest animal in the world.

Sloths with two and three fingers are not so similar

There are two species of two-toed sloths belonging to the family Megalonychidae and four species to three-toed sloths belonging to the family Bradypodidae. The two species are further relatives and have several significant differences between themselves. While three-toed sloths are active during the day, two-toed sloths are nocturnal animals. Three-toed sloths are also smaller and slower than their two-toed relatives.

However, both families have three toes each. The real difference relates to the claws on their hands. One family of these animals has two and the other three claws. To avoid confusion, some groups, such as the Sloth Protection Organization, are beginning to refer to them as two-finger and three-finger.

They are descendants of a giant sloth

Two-toed and three-toed sloths evolved from a giant sloth weighing several tons and nearly four feet tall. This animal became extinct about 10,000 years ago, probably because it was the prey of ancient humans.

They would not pass the eye test

These animals are not well known for their keen senses, and this is especially true for their eyesight. The female three-toed sloth cannot recognize her cubs at a distance of one and a half meters, and it has been observed that the males also try to fight from a similar distance. Scientists blame the mutation of the genes for this. Three-toed sloths are born without the dome-shaped cells in their eyes that they need to detect colors. As a result, they see in black and white and in worse resolution.

They are extremely good swimmers

Sloths are incredibly slow on land. Their legs are weak, so they have to use their upper body’s arms and strength to pull themselves forward. However, they can move three times faster in water. Their long arms make them skilled swimmers and they can hold their breath underwater for up to 40 minutes. If there is a water stream nearby, sloths can hop in and use the water as a shortcut to quickly navigate through the forest.

Their “laziness” is a survival tactic

Sloths move at a speed of two, two and a half meters per minute. Indeed, three-toed sloths are the slowest animals on Earth. When sloths were first documented in 18th-century scientific texts, they were described as the “lowest form of existence.” But because of their slowness, they did not die. Sloths are mostly dependent on leaves, and their four-part belly sometimes takes a month to digest one meal. Leaves are not nutritious enough, so sloths have to conserve as much energy as possible – which means less movement. And something else, their slow movement helps them stay unnoticed by predators that rely on sight to hunt.

Algae often grow on their fur

Sloths and algae depend on each other. Studies have shown that sometimes algae are transferred from the mother to her baby, and transmission is mutually important for both animals and plants. Long water-absorbent sloth fur makes it a comfortable home for algae, while sloths get greenish fur that helps them camouflage. Also, they eat algae, which gives them a much-needed source of nutrients.

Three-fingered sloths can turn their heads 270 degrees

This ability puts the three-eyed sloths in the same category with many owls. This is possible because of their bone structure. They have extra neck-based vertebrae that allow them to look in all directions with ease. Although these animals aren’t great on defense, at least they can see when the danger is approaching.

For such a helpless creature, they live a very long time

On average, they live about 20 years, while some species live longer in captivity. The world’s oldest sloth – the wife of a two-fingered Hoffman sloth named Miss Si – died last year at the age of 43. She spent her entire life at the Adelaide Zoo in Australia.