All About Xenarthrans

Additional joints, but almost no teeth – here you can find everything about xenarthrans and their unique characteristics!

All About Xenarthrans - Photos: (TL-BR) Parkol/Shutterstock, SunnyS/stock.adobe.com , Staffan Widstrand/stock.adobe.com , Honza123/stock.adobe.com

What Are Xenarthrans?

Xenarthrans are mammals that possess extra joints. These joints assist them in moving on the ground and climbing trees. The species vary greatly in appearance. Some have long fur – like sloths, for example. Others have a shell – such as armadillos. Their behaviors and abilities can also be incredibly different. Armadillos curl up into a ball when threatened, much like a hedgehog. Sloths remain motionless, hoping not to be noticed. The anteater, on the other hand, takes action: it defends itself with its sharp claws.

Main Characteristics of Xenarthrans

1. Extra Joints

Their scientific name literally means "strange joints". They are located in the thoracic and lumbar vertebrae. Whether strange or not, they are certainly very practical, as they make the spine quite flexible.

2. Sharp Claws

Xenarthrans have long, sharp claws. In sloths, they resemble long blades – which can be a bit creepy! Depending on their habitat, they serve different purposes. Sloths use them to hang onto branches. Anteaters have claws for digging in the ground for ants and termites.

3. Strange Teeth

While sloths and armadillos do have teeth, they lack enamel and tooth roots. Anteaters have no teeth at all, but they do have a long tongue.

4. Slow Metabolism

All xenarthrans have a slow metabolism. They obtain few nutrients from their food and therefore have little energy. As a result, they usually move very slowly – to conserve energy.

Xenarthran Family Tree

Amazing Facts Xenarthrans

• Xenartrhans are mammals. There are about 37 species.
• There are six species of sloths, ten species of anteaters and 20 species of armadillos.
• Xenarthrans have additional joints on the last thoracic vertebra and on the lumbar vertebra.
• Xenarthrans live in tropical areas in Central and South America, except for the nine-banded armadillo, which lives in southern North America.
• Xenarthrans are herbivores, insectivores, or omnivores.
• The sacrum and ischium are fused together, providing the animals with greater stability.
• Their metabolism is 40-60% slower compared to other mammals.
• The largest is the giant armadillo, which can reach lengths of 30-40 inches (75-100 cm) and weigh up to 120 pounds (54 kg).
• On the other hand, the smallest is the pink fairy armadillo, measuring only 3.5-4.5 inches (9-11.5 cm) in length and weighing just 4.2 ounces (120 grams).

Species List