International Sloth Day: Six Cosy Facts About the Laid-back Creatures From a Zookeeper

Today is International Sloth Day—a day to celebrate these enigmatic creatures, raise awareness for the species and perhaps take a leaf out of their book, enjoy some downtime and take things slow.

The day was established in 2010 by AIUNAU, an animal welfare group based in Colombia. To mark the occasion Newsweek has spoken to sloth keepers.

But first, a little bit of background.

Sloths are natives of the rainforests in Central and South America, where they can be found hanging in the tree canopies and subsisting on a (nearly entirely) vegetarian diet.

There are six extant species, which can be divided into two groups: three-toed sloths and two-toed sloths. The main difference between the two is—unsurprisingly—the number of digits on their front limbs. Two-toed sloths tend to be slightly larger—though nothing close to their extinct land-dwelling ancestor, the giant ground sloth, which could reach lengths of 10 feet and weights of a ton.

Three-toed sloths are also more docile and have smaller ranges of rainforest habitat that you can find them in, Kara Walsh, animal trainer at the San Diego Zoo Safari Park, told Newsweek.

The sloth's famously leisurely pace of roughly 40 yards on any given day has earned the animal a lazy reputation.

"Training a sloth has taught me more patience than any other animal I've worked with," said Walsh. "Moving slowly is a survival mechanism for sloths."

"Out in the wild, most of their diet is leaves, which are not very energy-rich. Sleeping more and moving slowly saves energy so they don't have to eat as much as other mammals."

But while it is true they like to spend a lot of time asleep—15 to 20 hours a day, according to the World Wildlife Fund—they can move fast when they want to, says John Partridge, the curator of animals at Bristol Zoo Garden in the UK. They also have a "nasty" bite, he added.

October 20 is International Sloth Day. iStock

Here are some other facts to celebrate International Sloth Day.

Fact 1: Their body temperature runs cold

"The day will include cleaning their exhibit, preparing their food and feeding them," Partridge says, describing the daily tasks that are required to keep sloths at the zoo. One of the more challenging aspects of the job is ensuring the temperature of the exhibit remains warm.

"Sloths are quite sensitive to temperature and humidity changes so checking to make sure that their exhibit is at the correct parameters is important," explained Partridge. "Sloths have a slightly lower body core temperature than most mammals and can become a little sluggish if their temperature is too low."

Fact 2: They have unusual toilet habits

Sloths have an incredibly slow metabolism and do not have to relieve themselves very often—but when they do, they can be quite picky about where they do it.

"They only go to the toilet once or twice a week and come down to the ground from the treetops to pass urine and feces at the same time at the base of a tree," said Partridge. "They often use favorite trees as toilet areas."

Fact 3: Sloths do almost everything upside down

"Everything about a sloth is adapted for life upside-down," said Walsh. "Their organs are situated differently from other mammals and even their fur grows in the opposite direction."

According to World Animal Protection, sloths spend 90 percent of the time hanging upside down. This is only possible because of certain physiological adaptations that bear the weight of their internal organs and prevent them pushing down on the diaphragm, researchers at Swansea University found.

As a result, they can breathe easily, even from this odd position.

Fact 4: They like to sunbathe

"Sloths like to sunbathe and will bask near the tops of trees to get warm, but that does make them vulnerable to predators like harpy eagles," said Partridge.

Algae can turn sloths' hair green. iStock

Fact 5: They have some surprising special skills

"They are very awkward walking on the ground, but they are very good swimmers," said Walsh. Sloths are surprisingly speedy in water, traveling three times as fast as they do on land.

Certain adaptations—including a large multi-chamber stomach—have proven to be extremely beneficial when it comes to navigating watery environments, BBC Wildlife Magazine reports. The stomach developed as a response to their slow digestion, but can also act as a flotation device.

Fact 6: Algae lives in their hair

Sloths are also unique in the fact that their hair grows in the opposite direction to most other mammals. What's more, a sloth's hair actually contains algae—a feature that helps camouflage the animal when its in the treetops, said Partridge.

In 2010, researchers found that a type of green algae called Trichophilus welckeri passes down from mother sloth to baby sloth, suggesting there is a co-evolutionary relationship between the two species.

Do sloths face any threats?

The biggest threat facing sloths is habitat destruction, says Partridge. They can also be the target of the exotic pet trade and may be poached by people hoping to make money from tourists' photos with the animals, adds Walsh.

The pygmy three-toed sloth is considered critically endangered on the IUCN Red List. The maned three-toed sloth is listed as endangered.