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16 Fun Facts About Tortoises

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May 23 is World Turtle Day. Celebrate the ultimate slow and steady land reptile with these fun facts about tortoises.

1. A tortoise is a turtle, but a turtle isn't a tortoise.

A turtle is any shelled reptile belonging to the order Chelonii. The term "tortoise" is more specific, referring to terrestrial turtles. (Of course, there's always an exception. In this case, the land-dwelling box turtle.) Tortoises are usually herbivorous and can't swim.

One easy way to tell 'em apart: look at their feet and shells. Water turtles have flippers or webbed feet with long claws, and their shells are flatter and more streamlined. Tortoises have stubby, elephant-like feet and heavier, domed shells.

2. A group of tortoises is called a creep.

But you won't see a creep very often. (Not that kind, anyway.) Tortoises are solitary roamers. Some mother tortoises are protective of their nests, but they don't care for their young after they hatch.

3. Tortoises inspired the ancient Roman military.

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During seiges, soldiers would get in testudo formation, named after the Latin word for tortoise. The men formed rows and held shields in front or above them to completely shelter the unit.

4. "Testudinal" means "pertaining to or resembling a tortoise or tortoise shell."

Go ahead. Compliment your friend's testudinal sunglasses.

5. Tortoises have an exoskeleton AND an endoskeleton.

The shell has three main parts: the top carapace, the bottom plastron, and the bridge that fuses these pieces together. You can't see them, but every tortoise has ribs, a collar bone, and a spine inside its shell.

6. The scales on the carapace are called scutes.

Made of the same keratin found in fingernails and hooves, scutes protect the bony plates of the shell from injury and infection. The growth rings around scutes can be counted to determine the approximate age of wild tortoises.

7. The lighter the shell, the warmer the origin.

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Tortoises from hot places tend to have lighter-colored shells than tortoises from cooler areas. The light tan sulcata originates from the southern part of the Sahara Desert.

8. They can't swim, but tortoises can hold their breath for a long time.

They're extremely tolerant of carbon dioxide. It's a good thing—tortoises have to empty their lungs before they can go into their shells. You'll often hear them exhale when they're startled and decide to hide.

9. And yes, their shells are sensitive to touch.

Shells have nerve endings, so tortoises can feel every rub, pet, or scratch ... and sometimes they love it. Note: This delightful creature is a turtle, not a tortoise.

10. Sulcatas are one of the most popular pet tortoises—and one of the biggest.

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Get ready to move to the suburbs and amend your will. Sulcatas are the third largest tortoise species in the world, behind the Galapagos and Aldabra giant tortoise. They can live more than 100 years and weigh up to 200 pounds.

11. Charles Darwin and Steve Irwin cared for the same tortoise, a Galapagos gal named Harriet.

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Darwin is said to have collected and named Harriet back in 1835. She was sent to England and eventually wound up at Australia Zoo, founded by Steve Irwin's parents. She finally passed on in 2006, the same year as the Crocodile Hunter's fatal encounter with a stingray.

12. Tortoises reach sexual maturity with size, not age.

It's a boy, err, uhh... You won't be able to tell a tortoise's sex until it reaches a certain size, which varies by breed. The most obvious tell is the plastron—for mating purposes, it's flatter on females and curved on males. Males also tend to be larger and have longer tails.

If you're a tortoise owner who prefers surprises, just wait for your pet to come out of his or her shell. Males will eventually display their private parts while soaking. And it's not uncommon for females to lay eggs, even without a mate to fertilize them.

13. They're the ultimate conservationists.

Tortoises can extract water and nutrients from even the most paltry bites. Their hindgut system works like a double digestive tract, separating water from their waste. When water's scarce, they'll hang on to water waste and simply excrete the urates, which look like white toothpaste.

14. They can smell with their throats.

Like other reptiles, tortoises detect the faintest of smells with the vomeronasal organ, or Jacobson's Organ, on the roof of their mouths. Instead of flicking their tongues, they pump their throats to circulate air through the nose and around the mouth.

15. Tortoises won the space race.

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In 1968, the Soviet Union's Zond 5 spacecraft was the first to circle the moon and return safely to Earth. The tortoises on board lost about 10 percent of their body weight, but were still ready for a meal when they touched down. That's one giant step for tortoisekind.

16. They might be smarter than we thought.

Slow and steady won the race in 2006 when scientist Anna Wilkinson placed a tortoise and rat in the same maze. The reptile was better at navigating the maze to find food, making sure it didn't revisit the same area twice. When cognitive landmarks were removed for a second trial, the tortoise systematically visited each section of the maze to find food. The rat wasn't as methodical. Previous research hasn't shown tortoises to be so clever, though: Wilkinson suspects cold lab temperatures are to blame. Later research found that tortoises use gaze-following to learn from the behavior of other animals.

All images courtesy of Thinkstock unless otherwise stated. 

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These Sparrows Have Been Singing the Same Songs for 1500 Years
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Swamp sparrows are creatures of habit—so much so that they’ve been chirping out the same few tunes for more than 1500 years, Science magazine reports.

These findings, published in the journal Nature Communications, resulted from an analysis of the songs of 615 adult male swamp sparrows found in six different areas of the northeastern U.S. Researchers learned that young swamp sparrows pick up these songs from the adults around them and are able to mimic the notes with astounding accuracy.

Here’s what one of their songs sounds like:

“We were able to show that swamp sparrows very rarely make mistakes when they learn their songs, and they don't just learn songs at random; they pick up commoner songs rather than rarer songs,” Robert Lachlan, a biologist at London’s Queen Mary University and the study’s lead author, tells National Geographic.

Put differently, the birds don’t mimic every song their elders crank out. Instead, they memorize the ones they hear most often, and scientists say this form of “conformist bias” was previously thought to be a uniquely human behavior.

Using acoustic analysis software, researchers broke down each individual note of the sparrows’ songs—160 different syllables in total—and discovered that only 2 percent of sparrows deviated from the norm. They then used a statistical method to determine how the songs would have evolved over time. With recordings from 2009 and the 1970s, they were able to estimate that the oldest swamp sparrow songs date back 1537 years on average.

The swamp sparrow’s dedication to accuracy sets the species apart from other songbirds, according to researchers. “Among songbirds, it is clear that some species of birds learn precisely, such as swamp sparrows, while others rarely learn all parts of a demonstrator’s song precisely,” they write.

According to the Audubon Guide to North American Birds, swamp sparrows are similar to other sparrows, like the Lincoln’s sparrow, song sparrow, and chipping sparrow. They’re frequently found in marshes throughout the Northeast and Midwest, as well as much of Canada. They’re known for their piercing call notes and may respond to birders who make loud squeaking sounds in their habitat.

[h/t Science magazine]

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16 Playful Facts About Otters
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These adorable aquatic mammals are clever, chatty, and oddly aromatic.

1. THERE ARE 13 SPECIES OF OTTERS, AND JUST ABOUT ALL OF THEM ARE DECREASING.

Only one otter species seems to be thriving, and that's the North American River Otter. The other 12 otter species were recently identified by the International Union for Conservation of Nature (IUCN) as having decreasing populations, and five otter species are already on the endangered list. Among the endangered are the sea otters along the California coast, which are threatened by "environmental pollutants and disease agents." Others, like the marine otters of South America, have had their numbers reduced because of poaching, as well as environmental concerns.

2. ZOROASTRIANS THOUGHT THE OTTERS TO BE NEARLY SACRED CREATURES.

This ancient monotheistic religion considered otters to be the dogs of the river or sea and had strict rules forbidding the killing of otters. It was thought that otters helped keep water purified by eating already dead creatures that might contaminate the water source if they were allowed rot. They would also hold ceremonies for otters found dead in the wild.

3. OTTERS HAVE VERY DISTINCTIVE POOP, AND THAT SCAT HAS ITS OWN NAME.

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Otters use their dung—known as spraint—to mark territory and communicate with other otters. The mammals like to keep things organized within their communities and will designate certain areas to be used as latrines. Spraint scents can vary, but often are (relatively) pleasant—one expert described them as not "dissimilar to jasmine tea." Spraint composition is unique to each otter, and the creatures can identify each other by the smells. Scientists suspect otters may even be able to determine the sex, age, and reproductive status of the spraint dropper just from a quick whiff. And since otters have superb metabolisms and must eat up to 15 percent of their body weight each day, there's a lot of spraint to go around.

4. OTTER MOMS ARE TOTALLY GAME FOR ADOPTION.

In 2001, a female otter at the Monterey Bay Aquarium gave birth to a stillborn pup on the same day a stranded pup was discovered in the wild nearby. The aquarium staff had previously tried raising pups themselves but found that hand-raised otters became too attached to humans to be released back into the wild. So instead, they dropped the pup in with the female otter, and she immediately went into mom mode. The aquarium has since devised a system of hand-rearing pups for the first 6-8 weeks—mostly for bottle feeding purposes—before handing the pups off to female otters for raising. At six months, the pups are released back into the wild with generally strong results.

5. THEY HAVE THE THICKEST FUR OF ANY MAMMAL IN THE ANIMAL KINGDOM.

Otters can have up to one million hairs per square inch. There are two layers of fur—an undercoat and then longer hairs that we can see. The layers manage to trap air next to the otter's skin, which keeps the otters dry and warm and also helps with buoyancy. Otter pups have so much air trapped in there, they actually can’t dive under water, even if they want to.

6. AN OTTER IS SOMETIMES ONLY AS GOOD AS HIS TOOLS.

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Otters love to eat shelled animals, like clams, but they aren't equipped with the strength to open their food without some help. Therefore, they are big on tools and will often use rocks to help crack into dinner. While they hunt for food underwater, they’ll often store a rock in the skin under their arms for later use.

7. OTTERS ARE POPULAR IN NATIVE AMERICAN CULTURE, BUT FOR VARYING REASONS.

Some tribes consider the otter to be a lucky animal and a symbol of "loyalty and honesty." But some, particularly in present-day Canada and Alaska, viewed the river otter "with awe and dread" and associated the creatures with the undead and drowning. They forbid eating the creatures and were offended when colonial Europeans began hunting the river otters and selling their furs.

8. GIANT OTTERS ARE SUPER CHATTY.

In 2014, a study of giant otters found that the river-dwellers have 22 distinct noises they make for different situations. On top of that, pups have 11 of their own calls that they intersperse with "infant babbling." Among the most notable calls: a "hum graduation" used to tell otters to change directions and a "Hah!" shout when a threat is nearby.

9. OTTERS AND HUMANS CAN COLLABORATE.

In Bangladesh, otters help fisherman maximize their haul. For centuries, fisherman have been training otters to act as herders and chase large schools of fish into the nets.

10. DRONES MAY HELP SCIENTISTS BETTER STUDY OTTERS IN THE WILD.

Keeping an eye on otters in the wild is a tricky task. In the past, observers have usually set up telescopes on shore to try and monitor otters at sea while on land. Otters won't act naturally with humans nearby, and using a telescope on a boat can get tricky in the rollicking ocean. But now, scientists are using unmanned drones with cameras to get an aerial look at otters in their element, making it easier to monitor the creatures as they dive for food and go about their day.

11. SEE A GROUP OF OTTERS? THAT'S A ROMP. OR A BEVY.

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Or a family or a raft. Otter groups go by a few different monikers, all of which are fairly unique to that crew. Generally, a group of otters on land will go by a romp, while a group hanging in the water is called a raft.

12. OTTERS ARE BIG ON PLAY TIME, AND MAKING SLIDES IS AMONG THEIR FAVORITE GAMES.

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Otter families are usually limited to pups and their mothers, and that duo will spend most of their time either feeding or sleeping. In the downtime, though, otters love to play and will often build themselves slides along the banks of rivers.

13. CALIFORNIA SEA OTTERS DIVIDE THEMSELVES IN DIET GUILDS.

Once thought to be gone from the area completely, southern sea otters—known as California sea otters—have been making a comeback in recent years. But with their numbers hovering around just a few thousand, researchers have kept a close eye on the population and their studies have revealed an interesting social structure. The otters, which need to consume 25 percent to 35 percent of their body weight every day in order to maintain their blubber stores and keep themselves warm in the cool waters, are divided into three "dietary guilds": Deep-diving otters that dine on abalone, urchins, and Dungeness crab; medium divers who subsist on clams, worms, and smaller shellfish; and those that stay in shallower waters, feeding on black snails.

14. THE FIRST EUROPEAN TO SET FOOT IN ALASKA WAS ALSO THE FIRST TO DESCRIBE SEA OTTERS.

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Georg Wilhelm Steller was the first to scientifically describe numerous new animals on the 1741 explorative voyage from Russia. Aboard the St. Peter, Steller and other 18th-century explorers crash-landed on mainland Alaska after getting separated from its sister ship. Steller was the first European to set foot on the icy land. Over the course of a rough Alaskan winter, he meticulously documented many species, and while some have since gone extinct (like a sea-cow he described that was hunted into extinction), the adorable otter was among his initial discoveries.

15. BABY OTTERS ARE BUOYANT, BUT THEY CAN'T SWIM ON THEIR OWN.

A mother will often wrap the babies in kelp to keep them in one place while she hunts. Or, she might rely on human resources and otter ingenuity to find a makeshift “playpen” for her pup.

16. THEIR BEHAVIOR ISN'T ALWAYS ADORABLE.

Like many animals, otters sometimes behave in ways that aren't exactly within the bounds of what humans would consider morally acceptable. Even if you find them otherwise adorable, otters' mating habits will no doubt make your stomach turn.

Male otters' mating techniques are violent. They bite their female partner's face during copulation to keep her from slipping away, leaving her with substantial facial wounds. It's not uncommon for female otters to die as a result of these aggressive encounters, either through drowning or from their wounds becoming infected. Male otters have also been known to violently copulate with other species—most notably, baby seals [PDF]. The behavior doesn't stop when the seals die from the trauma. Otters have been known to guard and have sex with the bodies of their victims for up to seven days after they've died.

Scientists hypothesize that these seemingly counterproductive mating habits might be the result of a population imbalance. In California's Monterey Bay, where scientists observed otters trying to copulate with the week-old bodies of dead baby seals, there are far more male otters than females. Facing a lack of female partners, male otters may be engaging in what researchers call "misdirected sexual activity." The area in the bay where the scientists observed the most otter-on-seal mating sessions was also where there was a high population of transient male otters, ones that, unlike more dominant males, don't have an established territory filled with potential mates. In the absence of females of their own kind, then, they turned their typical sexual responses toward the seals. Nature, unfortunately, isn't always pretty.

A version of this story originally ran in 2015.

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