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Sloth

life science Maturity 5-7 Next article →

Sloths are amazing mammals known for their very slow movement.

Three-toed sloth crossing road in Costa Rica
Three-toed sloth crossing road in Costa Rica

Most living sloths are tree dwellers in tropical rainforests. They live in South America and Central America. These animals spend most of their lives hanging upside down. They belong to a group called Xenarthra. This group also includes anteaters and armadillos. Sloths are closely related to anteaters. Together, they make up the order Pilosa.

Three-toed sloth crossing road in Costa Rica
Three-toed sloth crossing road in Costa Rica

Sloths have a special way of working to save energy. They have a very low metabolism. This means their bodies use energy very slowly. They eat leaves, which do not provide much power. Their slow movement helps them hide from predators. Hawks and cats hunt by sight. Moving slowly keeps the sloth from being seen. Their shaggy hair also helps them hide. Tiny green algae grow in the grooves of their hair. This algae provides nutrients and acts as camouflage.

Bradypus pygmaeus
Bradypus pygmaeus

Long ago, the world had different kinds of sloths. Many were ground sloths that lived on the land. Some were huge, like the Megatherium. This animal could be as big as an elephant.

Ground sloth size comparison
Ground sloth size comparison

These giants lived in North and South America. Most ground sloths became extinct about 11,000 or 12,000 years ago. This happened during the Quaternary extinction event. Some scientists think humans caused this. Others think climate change played a part.

Megatherium americanum Skeleton NHM
Megatherium americanum Skeleton NHM

There are six living species of sloths today. They are split into two groups. The first group is called Bradypus, or three-toed sloths. This group includes the brown-throated three-toed sloth. It is the most common kind. Another is the tiny pygmy three-toed sloth. It lives on Isla Escudo de Veraguas near Panama.

Bradypus pygmaeus
Bradypus pygmaeus

The second group is Choloepus, or two-toed sloths. These are slightly larger than three-toed sloths. They have two digits on each front limb. However, they still have three toes on their back limbs.

Two-toed sloth Costa Rica - cropped
Two-toed sloth Costa Rica - cropped

Sloths are very different from many other mammals. Most mammals have seven neck bones. Sloths are unusual because they do not. Two-toed sloths have five to seven neck bones. Three-toed sloths have eight or nine. They also have poor hearing and vision. They rely on smell and touch instead. Even though they are slow on land, they can swim. This shows how adaptable these creatures can be. They have survived in many different ways over millions of years.

Megalonyx wheatleyi skeleton & restoration
Megalonyx wheatleyi skeleton & restoration
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🖼️ Images & Media (10)
File:Three-toed sloth crossing road in Costa Rica.jpg
Three-toed sloth crossing road in Costa Rica.jpg
File:Megatherium americanum Skeleton NHM.JPG
Megatherium americanum Skeleton NHM.JPG
File:Nothrotheriops shastensis La Brea.jpg
Nothrotheriops shastensis La Brea.jpg
File:Megalonyx wheatleyi skeleton & restoration.jpg
Megalonyx wheatleyi skeleton & restoration.jpg
File:San Diego Paramylodon.jpg
San Diego Paramylodon.jpg
File:MC Drei-Finger-Faultier.jpg
MC Drei-Finger-Faultier.jpg
File:Ground sloth size comparison.png
Ground sloth size comparison.png
File:Two-toed sloth Costa Rica - cropped.jpg
Two-toed sloth Costa Rica - cropped.jpg
File:Bradypus pygmaeus.jpg
Bradypus pygmaeus.jpg
File:SlothDWA.jpg
SlothDWA.jpg
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