Being a Sloth Has Its Perks, If You Like to Hang Upside-Down

According to National Geographic and the American Red Cross, the average human has around 2 gallons of blood in their body. Can you imagine what happens internally when you go upside down? Lucky for us, humans are not made to spend a lot of time hanging around from trees. Bats and sloths on the other hand are made for the upside-down lifestyle. 

Bats both large and small do not have enough blood in their bodies for gravity to affect them while hanging upside-down. In fact, it’s actually easier for them to hang from a tree than it would be for a bat to sit upright. If you think about it, have you ever seen a bat sitting upright? 

For sloths, it seems that a favorite way to photograph them is when they are hanging from the limbs of a tree but in reality, they are not upside-down as often as perceived. Also, when they are traveling through the rainforest by clinging from branch to branch it is at an incredibly slow rate. So slow, that their bodies are not fazed by being upside-down. Don Moore, the Associate Director at the Smithsonian National Zoo in Washington D.C, has said that the two-toed sloth does not move their head and keeps their nose level with the with the branch while traveling the forest. Doing so, ensures they do not get dizzy. The three-toed variety does the opposite and flips their head 180 degrees to watch where they are traveling. 

Nature has made it possible for animals to do exactly what they were built for, whether it’s walking upright as a human, or hanging from a branch like a bat or sloth. 

Resources:
http://news.nationalgeographic.com/2015/08/150829-animals-science-sloths-bats-health-biology/
http://www.redcrossblood.org/learn-about-blood/blood-facts-and-statistics

A Night With A Sloth

What do you do when you receive a mysterious email inviting you have a cocktail with a sloth? You go of course! The California Academy of Sciences holds a NightLife event every Thursday from 6pm to 10pm. On March 16th, 2017 that event was dedicated to nocturnal animals and thanks to Classroom Safari and founder Bonnie Cromwell, a Two-Toed Linneaus Sloth named Willow was present. 

Willow was rescued from a pet store in Florida after she was bred in captivity. Classroom Safari was able to rescue her from an unideal situation and provide her a new “forever home.” Now Willow is being properly cared for and enjoying her time with Bonnie and the other educators, when she is not busy helping out with educational outreach programs. Those programs and private events are geared toward conservation and animal information. Classroom Safari was founded by Bonnie 38 years ago, so her love of animals reaches both children and adults and assists in teaching about how important it is to conserve the lives of animals that most people never see. 

Now back to sloths. Willow is currently around one year old and only weighs 6 lbs. She will eventually reach around 20 lbs when she is full grown. An interesting fact about Thursday night at NightLife was that it was “poop” night for Willow. Sloths only relieve themselves every 4 days and Thursday lined up as the lucky day. When sloths finally relieve themselves, they can lose one third of their body weight, resulting in a fairly large clean up. Leading up to bathroom time, sloths are very lethargic and once the business is done, they are ready to play all night. 

Bonnie spoke about her discussions with researchers who studied sloths in the Costa Rican rainforest and told a story about a pretty sly male sloth. The male sloth was always in the same spot, on the same tree, every single day. So naturally, the researchers assumed the sloth didn’t move very much and stayed in the tree. One night they set up cameras to catch any night time activities between the sloths in the forest and got quite a surprise when reviewing the footage the following day. The male sloth had numerous hot dates that night. Researchers counted 11 dates, each with a different female sloth. At the end of his night, he returned to his favorite spot, on his favorite tree, proving not only is not there not enough research on these amazing creatures, but that they might not be so “sloth like.”

Resources:
https://www.classroomsafari.org/
https://www.calacademy.org/nightlife/nocturnal-nightlife

A Rainforest Home

Sloths live in the beautiful rainforests near the equator.  This tropical ecosystem has fairly consistent conditions.  Being close to the equator, the length of day and night during the year does not vary much.  There are nearly daily afternoon rains.  The air is humid and warm, and the temperature is consistently in the high 70's (Fahrenheit).  

Within that consistently, rainforests are very complex.  Rainforests cover only 6% of the earth’s surface, but have more than half of the planet’s plant and animal species! The rainforest has multiple levels of plants:  the highest are the tall treat that often form a canopy.  The next level is vines, orchids, and epiphytes that grow high up in the trees.  Down lower are the ferns and other short trees, and then there is the forest floor.  Each level has its own complex variety of animal life.

Sloths spend almost their entire lives high up in the canopy of the trees.  If you were in a rainforest, which part would you want to hang out in?

The Nose as the Center of the Universe

A sloth’s nose is it’s primary navigation system.  In a sea of tropical green, searching for tasty leaves with eyes is not going to be very productive.  Sloths are fairly short-sighted and do not have eyes that are developed for adjusting the lens to see distances.  A sloth can even retract its eyes into its eye sockets!  Sloth pupils usually stay small, even at night.

Instead, a sloth uses its nose.  The sloth basks, hanging easily from the trees, and immerses itself in a constant flow of scent wafting through the jungle.  It tests out every scent and heads off in the direction of the most delicious one…usually a tasty Cecropia tree.  Can you smell your way to your next dinner?

Quiet But Noisy

Sloths use their abilities with ultrasound to stealthily make their way through the forest canopy. Many other animals also use frequencies that are outside of the range of average human hearing.

A lot of animal acoustics are not understood very well by humans, because the humans don’t perceive the sounds and therefore are limited by their own capacities.  New technologies often help open up more information, but since the technologies are invented by humans who are starting with a certain perception set, it will always be an incomplete set of information.

Scientists have listened to whale songs for many years, but they were only listening to the surface part of the song:  the audible melody.  What they didn’t realize was the effect of all of the vibrations in the spectrum of the whale song that were flooding through the water other than what was audible.

Part of the whale’s communication involves vibrations that are not audible, but that can be felt by other sea creatures.  Other whales can feel the vibrations (like when you feel the large bass booming from a stereo system) and pick that up as part of the message.  Sound travels farther in water than in air, so whales can send these tactile communications through sound vibrations much farther.

Many animals “feel” sound as part of their communication beyond what is audible.  Humans also “feel” sound, and can become aware of more subtleties of communication by becoming aware of sound at the tactile vibrational level.  A thoughtful sloth has much to explore!

Read more about the whale research at: Whales Can Really Rock With Their Mellow Songs

Silence in Motion

If you were to go to the jungle and tromp through the undergrowth, you would make a lot of noise.  And many things would react to the sound and motion that you were making:  birds might fly up and around, small creatures would scurry, monkeys would scream and scamper across the trees.

But a sloth would stay still and motionless, high up in the canopy, unconcerned with your irrelevant ramblings.  The sloth is so good at blending in and moving in stillness, that it took researchers years to discover that up to 700 sloths might live in one square kilometer of forest.  To compare, the same amount of space would only contain about 70 howler monkeys — and you would for sure know they were there!

Can you move slowly and silently like a sloth?  Try it and see!  Or are you more like a howler monkey?  Can you do both things?  It actually takes some skill and concentration to move so slowly and silently, what a fun game to play!

Sloth Facts: Anatomy for Being Upside-Down

While we all know that sloths are incredibly cute, there is still a lot to learn about sloths and how they live.

One thing that scientists discovered a few years ago is that sloths have special tissue adaptations so that they can easily maintain hanging upside-down without expending extra energy or putting pressure on their organs.

Imagine if you hung upside down all day long:  your lower organs would start pushing down on your lungs and diaphragm, which would make breathing harder and harder as the day went on.

Sloths have special tissue that anchors their liver and stomach to the lower ribs, and anchors the kidneys to the hip bones.  This helps make sure that the ribs are bearing the weight of the organs as they hang upside down.

By measuring lung capacity and breathing rates of sloths, the scientists estimated that having this tissue in place helps them conserve 7 - 13 percent more energy that they would otherwise expend simply breathing.  Since sloths are slow moving and take a long time to digest their food, this energy conservation is important.

More tissue stability likely makes the sloth less flexible.  But that’s OK because they go slow!

References:
National Geographic Blog: "To Breathe Upside-Down, Sloths Tape Organs To Their Ribs"

Sloth Scientist article by Becky Cliffe,  "SLOTH ORGANS HANG ON 'COAT HANGERS' FOR EASY UPSIDE-DOWN BREATHING"

Sloth Muscle

Sloth movement is different from many other mammals — you can see that by the way they move so slowly from limb to limb of the trees, high up in the canopy.

For sloths, only 25 to 30 percent of their body weight is muscle.  In most mammals, muscles make up 40 to 45 percent of body weight.  Since sloth digestion is so slow, much of the time a large proportion of their body weight is made up of undigested food matter or waste product that they have not yet gotten rid of.

Sloth muscle also tends to react slower in comparison to other animals.  On the other hand, it can stay contracted much longer.  That allows it to move slowly and stay in one position for a long time without tiring.

That fixed sloth-smile look that sloths have comes in part from this minimized muscle mass in combination with their fur markings.  Sloths don’t have the muscle capacity to make lots of facial movement, like many humans and some other animals do.  Instead, their ‘facial expression’ comes from the fixed image of their fur markings.  Movement of the face is reserved for the mouth and nose, which do the job of perceiving scent and taking in food.

What a cute look!

Source: What Does It Mean to Be a Sloth?

Respect the Sloths!

We all know how cute, adorable, and lovable sloths are!  It would be easy to want to treat them like a teddy bear, but sloths are very independent creatures who deserve respect.  We are able to show respect when we take the time to know what is best for the sloth to thrive in its natural environment.  

Because sloths are slow, it might be easy to catch up to one in the wild or in tourist areas.  But that doesn’t mean it’s a good thing to do.  If a sloth gets scared, it might freeze.  If you notice that a sloth is reacting to you, give it some more space.  As cute and friendly-looking as sloths are, they are not the same as domestic animals who are used to continual human contact.  And even cats want their own space sometimes!  Sloths are highly solitary, not even spending a lot of time with other sloths.  So please keep your distance and respect them.  Human contact can be extremely stressful to a sloth.

This also means not falling for tourist traps that have you pay to hold a sloth or take a picture with a sloth.  If you want to visit sloths, make sure you do your research and find a place that is devoted to the care and respect of sloths, and which takes good care of sloths who cannot otherwise live in the wild.  Read more about respecting sloths in this article by The Sloth Institute of Costa Rica’s co-founder Sam Trull.

Evolutionary Sloth Moths

In this fascinating article by Dr. M. Alma Solis, Research Entomologist at the National Museum of Natural History (Smithsonian Institute), Dr. Solis recounts the history of how scientists learned about sloth moths.

Back in 1907, during a Smithsonian Biological Survey of Panama, a Lepidoptera (moths & butterflies) curator noticed that when a sloth fell from a tree, many small moths flew out of the fur on impact.  About 60 years later, other scientists realized that the caterpillars of the moths lived and fed on sloth dung, where their mother’s laid eggs.  Since then, scientists have catalogued multiple species of sloth moths in different locations.

The subfamily of moths that the sloth moths belong to, Chrysauguine, is mostly filled with bright-colored moths whose caterpillars feed on plants.  Sloth moths, on the other hand, have evolved to be dull-colored brown as camouflage in sloth fur.  They also do not have the same ability to produce sound with their wings as other Chrysauguine moths.  Perhaps the sloths appreciate the quiet!

Sloth Encounter! Visit to the Scoville Zoo

We had a business trip planned to Decatur, Illinois and then learned that a sloth lives at the Scoville Zoo!  So of course, visiting the sloth went to the top of the agenda.

Scoville Zoo opened to the public in 1967, and is now home to more than 400 animals.  The Zoo is accredited by the Association of Zoos and Aquariums, which means it meets the highest standards for animal care, exhibit maintenance, education, conservation, and administration.  It is a small zoo, easy to visit in just a few hours, and has play areas, a petting zoo, a carousel, and a train ride.

Most importantly, however, Scoville Zoo is home to a sloth!

A lovely female two-toed sloth spends her time at the zoo, hanging out and nibbling on treats.  Check out these pictures of the beautiful sloth.  Some are dark, but we wanted to avoid using a flash and startling the sloth:

Documentary: A Sloth Named Velcro

Watch this documentary about Velcro, the orphaned sloth, and the amazing things we are learning about sloths:

Pygmy Sloth Video

The pygmy sloth, who only lives on one island, looks like a tiny teddy bear and is very good at swimming.   The BBC did a documentary on this relaxed, island-dwelling sloth.  Take a look at some of the video here to see live pygmy sloths swimming:

BBC Page on Pygmy Sloths

(click on the "Pygmy Sloth Discovery" Link at the bottom for the video)

Pygmy Sloth illustration

Mystery of the Pooping Sloths: Part One

Sloths digest their food very, very slowly.  They only go poop one time per week!  And when they do, they can drop 1/3 of their body weight in one go.  

When a sloth has to go, it climbs all the way down to the base of the tree to go poop.  For a slow-moving animal, being on the ground is not the safest place to be.  So why would a sloth go all the way down to poop?

Watch this video for a few theories, and then stay tuned for part two!

A Rolling Stone Gathers No Moss, But A Hanging Sloth Gathers Algae

Have you heard the phrase "a rolling stone gathers no moss"?  The Mythbusters have proved this is true:  after rolling a stone continuously for six months, it did not grow any moss.  The rolling stone has too much motion for the moss to be able to grow.

But a slow, slow, hanging sloth DOES gather algae.  Sloth hair is long and coarse, with good texture for creating a habitat for other organisms.  When scientists studied algae on sloth fur, they found that the most common algae was Trichophilus welckeri.  Mother sloths pass this on to their babies, so that young sloths are carrying their own algae colonies by the time they are a few weeks old.

So far, the scientists have not found this particular algae in any other environment, meaning that  there is likely a unique symbiotic relationship between the sloth and the algae.  The hair on two-toed sloth and three-toed sloths is different:  two-toed sloths have deep grooves that run the length of each hair; three-toed sloths have irregular cracks across the hair that increase in number with age (hair wrinkles!).  So three-toed sloths in particular will get a green-ish tinge to their hair from the algae co-habitating in their hair wrinkles.  This makes for good camouflage for our slow moving sloth friends.

Check out the green algae on this three-toed sloth, especially on the sloth's head and arms.

Research Article:  Molecular evidence for a diverse green algal community growing in the hair of sloths and a specific association with Trichophilus welckeri(Chlorophyta, Ulvophyceae)