sloth

Sloths are animals that are 24 to 31 inches long. They weigh between 7.9 and 17 pounds as adults. Two-toed sloths have two toes on their front feet and three toes on their back feet. Three-toed sloths have three toes on all feet and a stubby tail that varies in length from 2 inches to 2.4 inches. Between the two, the two-toed sloth is the larger. Both types have long arms and legs, round heads, and small ears.

Other differences between two-toed and three-toed sloths include the number of bones in their necks. Two-toed sloths have five to seven cervical vertebrae. Three-toed sloths have eight or nine of these vertebrae. Among all other mammals except manatees, this makes these animals unique. All other mammals have seven cervical vertebrae, except manatees, which have six, and sloths, which have between five and nine. Thanks to extra cervical vertebrae, sloths can turn their heads farther than humans.

These animals have poor eyesight and hearing. But they can see color. Since these senses are poor, they rely heavily on smell and touch.

These mammals also have very slow metabolisms and low body temperatures. Their temperature can be as low as 68 degrees Fahrenheit depending on the environment. But that range usually stays between 77°F and 95°F.

Unlike other mammals, the outer layer of sloth fur grows in the opposite direction from other mammals. Mammalian hair usually grows down the arms and legs. But sloths have hair that grows from their arms and legs and parted down the middle of their chest and abdomen. This provides better protection from the elements, as they spend most of their lives hanging upside down.

Because this is the slowest mammal, their fur has algae growing in each hollow hair. This green algae acts as camouflage, helping the animals hide from predators in the treetops. The fur-eating creatures in this particular ecosystem are mosquitoes, sandflies, lice, mites, ticks, beetles and moths. The moths fertilize the algae on their fur, helping more growth.

The limbs of these animals allow the mammals to hang from tree branches. But those limbs don't support their weight very well. This makes the animals helpless and awkward on the ground. They can only drag themselves on the ground with their paws. So they come out of the treetops only once a week. They do this to free themselves and return to the trees, where they are less threatened by predators.

Despite being unsafe or unable to move well on the ground, sloths swim well. They do the breaststroke like a human, propelling themselves through the water with ease on their long, slender limbs. Their bodies also float very well.

These animals don't spend time around each other except for mating and raising their young. They show aggression towards sloths of the same sex. They mostly lead solitary lives at night.

Modern sloths live in Central and South America. But their ancestors lived in North America. In Central and South America, they prefer taller trees in tropical rainforests, cloud forests, and mangroves. Each sloth moves around several trees during its lifetime. But many people spend their entire lives in the same tree they were born in.

These animals hang from tree branches to sleep, eat, mate and raise their young. The only reason animals leave the treetops is to go to the toilet once a week, find a mate, or expand their territory.

Three-toed sloths eat mostly plants, making them herbivores. They prefer the leaves of the leafy beetle tree. Two-toed sloths eat both plants and small animals. They love leaves, fruit, small lizards and insects.

These mammals have multi-chambered stomachs that contain many bacteria that decompose plant material. They digest food very slowly. It takes them a week to a month to digest most food. These foods are also low in nutrients, so they don't get energy from most foods. Scientists believe this lack of energy is why they move so slowly.

Key predators of these animals include jaguars, snakes, large birds of prey and humans. They defend themselves by swiping at predators with long, sharp claws that extend out of their long arms. Humans who hunt sloths have realized that shooting them may be pointless, since the animals tend to hang from tall tree branches with their claws even when dead. The animals' best defense against any predator is to use their algae-covered fur as camouflage in trees.

These slow-moving animals eat poison ivy because it harms the animals that eat them. Although they can easily die at the hands of snakes, jaguars, or large birds of prey, the poison ivy in their bodies can suffocate the animals that eat them. The plant's toxin causes the predator's throat to swell, stopping it from breathing.

In addition to animal predators and humans, these animals face other survival challenges. Sloths are believed to have existed on Earth in one form or another for at least 40 million years. But today, they face threats from habitat destruction, road construction, traffic, power lines, tourism and the pet trade.

Some species mate at the same time each year. Maned sloths breed year-round. Three-toed sloths give birth one at a time after six months of pregnancy, while two-toed sloths have a 12-month pregnancy. These newborns lived with their mothers for five months. During this time, they cling to the mother's body. Sometimes they drop to the forest floor and their mother is either too lazy or too slow to pick them up. As a result, the baby died not from the fall, but from where it landed.

When babies are five or six months old, they leave their mothers. They claim a piece of her territory as their own. Although they no longer lived together, the mother and her offspring continued to communicate throughout their lives. They "talk" to each other with loud calls.

For humans, it can be difficult to tell if an animal is female or male. The genders that zoos receive are often unexpected. Scientists don't yet know how long these animals live in the wild. But in human care, the average lifespan of a sloth is about 16 years. A female at the Smithsonian's National Zoo lived 49 years.

These animals continued to thrive in South and Central America. On Panama's Barro Colorado Island, these animals make up 70 percent of the tree-dwelling mammals. Four out of six living sloth species on Earth are not facing extinction. They are listed as "Least Concern". But the maned sloth in eastern Brazil is classified as "vulnerable." The Panamanian pygmy sloth that lives on the country's islands is critically endangered.

Multiple sloth conservation organizations exist today. They work to protect the habitat and the animals themselves. These organizations educate people about the biology, ecology and conservation of these animals. They also rehabilitate injured sloths and release them back into the wild.

about the author

Lisa Pace

After a career providing opportunities for local communities to experience and create art, I enjoy having time to write about two of my favorite things – nature and animals. I spend half my life outside, usually with my husband and adorable 14 year old puppy. We enjoyed walking around the lake and taking photos of the animals we encountered including: otters, osprey, Canada geese, ducks and nesting bald eagles. I also enjoy reading, discovering books to add to my library, collecting and playing vinyl records, and listening to my son's music.