A three-toed sloth looking candid while hanging in a tree.

There are times when we feel heavy and lethargic and simply cannot move. For sloths, it is a way of life. Sloths -- especially the three-toed sloth -- is considered one of the slowest animals on our planet. However, although sloths are mostly defined by their slowness, there are other unique characteristics to this animal that we might be interested to know.

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SLOTHS ARE BLIND

One of the reasons why sloths are incredibly slow is they're mostly blind and it doesn't help that they are diurnal as the sunlight is always too bright for them. By moving slowly, sloths ensure their safety while navigating trees.

SLOTHS HAVE SLOW METABOLISM

The primary cause of the sloth's slowness is that it has the slowest metabolism rate in all of the class Mammalia. Because of its slow metabolism, sloths are efficient energy savers conserving up to 90% more energy than other mammals.

SLOTHS ARE EFFICIENT CLIMBERS

The sloth is known for its long claws -- either to or three depends on the species -- which they use to climb trees. A specialized tendon helps the sloth hang upside down in the branches of trees and a well-developed circulatory system that prevents blood from going to the brain while hanging upside down. These animals spend the majority of their time in trees, usually in the canopy and only comes down to relieve themselves, find food, and in the right season, mate. Their preference for staying high up in trees is purely survival instinct: the tree cover protects them from their natural predators like jaguars and eagles. The algae provide the camouflage as well as extra nutrients needed by the sloths. In return, sloths feed algae with water absorbed in its fur.

It is also important to note that a sloth's organs are attached to its rib cage. This is why they have no trouble hanging upside down for a long time.

SLOTHS ARE GOOD MOTHERS

One of mammals' winning design is giving live birth and the ability to produce only one well-developed offspring at a time being. Sloths are no exception. After a gestation period of six months, female sloths give birth to a single baby and takes care of it for another six months. The infant sloth will cling to its mother's belly as they travel through trees and feed. During these six months of a young sloth's bonding with its mother, it learns to communicate with parents by learning its mother's call range.

SLOTHS ARE HERBIVORES

The diet of sloths consists mostly of leaves, twigs from trees, and buds. As herbivores, their dental system lacks incisors and instead, a gap called the diastema is present. Also, due to the lack of incisors, sloths trim down leaves by smacking their lips together. Because of their slow metabolic rate, sloths can survive on little food compared to other mammals. 

SLOTHS ARE SIMPLY UNIQUE

Unlike most mammals, sloths are able to turn their heads in an almost 360-degree angle. This is a highly beneficial defense mechanism for sloths as they get to view their surroundings without moving much and this is all thanks to an extra vertebra found at the base of their neck. 

The facial muscles of sloths make them appear to be smiling all the time so even though it is in an unfamiliar environment and completely stressed, it can be seen with a grin.

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