iStock
iStock

7 Myths and Misconceptions About Crocodilians, Debunked

iStock
iStock

There are a lot of myths out there about crocodilians, the order to which both alligators and crocodiles belong. Evon Hekkala, the principal investigator at Fordham University’s Hekkala Lab and a research associate at the American Museum of Natural History, spoke with mental_floss after the opening of AMNH’s latest exhibition, “Crocs: Ancient Predators in a Modern World,” to get to the truth.

1. MYTH: THEY CAN RUN AS FAST AS A RACEHORSE.

Winning Brew, the Guinness World Record holder for Fastest Racehorse, clocked in at nearly 44 mph during her record-breaking run. Crocs don’t get anywhere near that fast on land. “They top out at about 12 mph on land, and they can only do it for a really short period of time—for maybe 20 or 25 meters,” Hekkala says. “A really fast human race walker, goes about 11 or 12 miles on land. In other words, without even breaking into a run, most people could actually outrun a crocodile.”

In the water, though, it’s a different story: Crocs still aren’t as fast as racehorses, but they can reach speeds a little over 20 mph. “I wouldn’t want to try to outrun one in the water,” Hekkala says.

2. MISCONCEPTION: THEY’RE LIZARDS.

Though people often refer to crocodilians as lizards, lizards are an entirely separate order not related to crocodilians at all. According to Hekkala, “[Crocodilians] are the other lineage of living archosaurs,” a.k.a. “ruling reptiles,” which have two lineages: “There’s the lineage that includes dinosaurs and birds and then there’s the lineage that includes crocodiles, and they’re each other’s closest relatives,” she says. “They’re quite distant from lizards, even though they look sort of superficially similar.” And speaking of that …

3. MISCONCEPTION: CROCODILES AND ALLIGATORS ARE BASICALLY THE SAME.

Though crocodiles and alligators look very similar, their last common ancestor lived 65 million years ago. “That’s about as far back in time as when the primates diverged from things like bats,” Hekkala says. “They look really similar because it’s a really great body plan that works really well, and there’s no need to change that. So even though they look superficially like they’re the same thing, they’ve evolved on different pathways for a really long period of time.”

4. MYTH: THEY’RE DUMB.

“A lot of people think [crocodilians have] tiny lizard brains,” Hekkala says. “But actually there are people at the American Museum of Natural History who are studying the evolution of the brain in birds, dinosaurs, and crocodilians, and the brain is much more complex than we previously thought.”

Like birds, crocodilians have complex social systems (more on that in a minute), and they can even be trained. “There are people recently who have been training captive populations of crocodiles to come to a clicker so that they can get their veterinary treatment, and it’s working,” Hekkala says. Crocs can be trained the same way you train a dog or a cat: The croc comes to the clicker and gets a treat, reinforcing the desired behavior.

5. MISCONCEPTION: THEY EAT THEIR YOUNG.

OK, now on to that complex social behavior. “There was a myth, for a long time, that crocodilians were these terribly baby-eating predators,” Hekkala says. “A long time ago, people would observe the crocodiles and alligators digging up nests and having hatchlings in their mouths, and they would think that they were eating them.” In reality, the baby crocodilians were actually calling out to their parents for help out of the nest as they were hatching, and when moms were walking around with babies in their mouths, it was because they were taking their young to the water. “There’s parental care and communication,” Hekkala says. Male crocodilians will occasionally cannibalize young, but “typically, when you see a crocodile or an alligator with babies in its mouth, it’s helping, not hurting.”

The animals can delicately carry their young thanks to pressure sensitive pits in their skin. “Alligators only have them on part of their jaw, but crocodiles actually have the pits all over their skin, everywhere—all over their face, all over their bodies, and they’re unbelievably sensitive to pressure, and these were only recently discovered,” Hekkala says. “It’s an amazing new finding, and that’s probably one of the things that allows them to be so gentle with the hatchlings.”

6. MYTH: THEIR SKIN IS SUPER HARD.

If you looked at a crocodilian, or had a purse made of their skin, and thought their armored skin was super hard, you wouldn’t be alone. “Most people’s experience of any kind of crocodilian skin is a tanned leather purse or something like that,” Hekkala says. “Those things are made to be hard so they can be sturdy, but their skin is actually quite soft, and very sensitive.”

Rather than having scales like lizards, crocodilians have skin with bony plates underneath in certain areas. “This is going to sound weird,” Hekkala says, “but if you were holding a crocodile’s hand, it would feel strangely similar to a human hand. A little cooler unless they’d been hanging out in the sun, but yeah.”

7. MISCONCEPTION: THERE ARE TWO LIVING CROCODILIANS—ALLIGATORS AND CROCODILES.

Millions of years ago, crocodilians were a very diverse group, living in the sea and on land and ranging in size from small, cat-like creatures to creatures huge enough to dine on T. rex. These days, most people think that there are just two living crocodilians—alligators and crocodiles—but there are actually many more than that. “There are two species of alligator: the one we’re familiar with in North America, and the Chinese alligator, which is critically endangered,” Hekkala says. “When I first started my research into crocodiles, there were thought to be 11 species of true crocodiles in the genus Crocodylus, but we’re discovering more and more species.”

By analyzing the DNA of museum specimens, Hekkala discovered that the Nile crocodile was not one species of croc but actually two. And that was not an outlier: “Now we know that the dwarf crocodile that’s in the exhibit is three species, and we think that the African slender snouted crocodile is now two species,” she says. “So since 2009, just from molecular research, we’ve added—just in Africa—four new species of crocodile.”

The American Museum of Natural History’s “Crocs: Ancient Predators in a Modern World” runs until January 2, 2017.

nextArticle.image_alt|e
iStock
arrow
Animals
14 Bold Facts About Bald Eagles
iStock
iStock

Bald eagles are powerful symbols of America—but there’s a whole lot more to these quirky birds.

1. YOUNG BALD EAGLES AREN'T BALD.

A young bald eagle with a brown head on a beach.
iStock

So obviously adult bald eagles aren't really bald, either—their heads have bright white plumage that contrasts with their dark body feathers, giving them a "bald" look. But young bald eagles have mostly brown heads. In fact, for the first four or five years of their lives, they move through a complicated series of different plumage patterns; in their second year, for instance, they have white bellies.

2. BALD EAGLES SOUND SO SILLY THAT HOLLYWOOD DUBS OVER THEIR VOICES.

A red-tailed hawk.
A red-tailed hawk's screech is usually dubbed over the bald eagle's weaker scream.
iStock

It's a scene you’ve probably seen countless times in movies and on TV: an eagle flies overhead and emits a rough, piercing scream. It's a classic symbol of wilderness and adventure. The only problem? Bald eagles don't make that sound.

Instead, they emit a sort of high-pitched giggle or a weak scream. These noises are so unimpressive that Hollywood sound editors often dub over bald eagle calls with far more impressive sounds: the piercing, earthy screams of a smaller bird, the red-tailed hawk. If you were a fan of The Colbert Report, you might remember the show's iconic CGI eagle from the opener—it, too, is making that red-tailed hawk cry. Listen for yourself and decide who sounds more impressive.

3. THEY EAT TRASH AND STOLEN FOOD.

Two bald eagles guard their prey against two magpies on a snowy field.
iStock

Picture a majestic bald eagle swooping low over a lake and catching a fish in its powerful claws. Yes, bald eagles eat a lot of fish—but they don't always catch it themselves. They've perfected the art of stealing fish from other birds such as ospreys, chasing them down until they drop their prey.

Bald eagles will also snack on gulls, ducks, rabbits, crabs, amphibians, and more. They'll scavenge in dumpsters, feed on waste from fish processing plants, and even gorge on carrion (dead, decaying animals).

4. BALD EAGLES USUALLY MATE FOR LIFE.

Two bald eagles perched on a tree.
iStock

Trash and carrion aside, they're pretty romantic animals. Bald eagles tend to pair up for life, and they share parenting duties: the male and the female take turns incubating the eggs, and they both feed their young.

5. … AND THEY LIVE PRETTY LONG LIVES.

Two bald eagles sitting on a rock.
iStock

Those romantic partnerships are even more impressive because bald eagles can survive for decades. In 2015, a wild eagle in Henrietta, New York, died at the record age of 38. Considering that these birds pair up at 4 or 5 years of age, that's a lot of Valentine's Days.

6. THEY HOLD THE RECORD FOR THE LARGEST BIRD'S NEST.

Two bald eagles in their large nest.
iStock

Bald eagles build enormous nests high in the treetops. The male and female work on the nest together, and this quality time helps them cement their lifelong bond. Their cozy nurseries consist of a framework of sticks lined with softer stuff such as grass and feathers. If the nest serves them well during the breeding season, they'll keep using it year after year. And, like all homeowners, they can't resist the thought of renovating and adding to their abode. Every year, they'll spruce it up with a whopping foot or two of new material.

On average, bald eagle nests are 2-4 feet deep and 4-5 feet wide. But one pair of eagles near St. Petersburg, Florida, earned the Guinness World Record for largest bird’s nest: 20 feet deep and 9.5 feet wide. The nest weighed over two tons.

7. FEMALES ARE LARGER THAN MALES.

Two bald eagles in their large nest.
iStock

In many animal species, males are (on average) larger than females. Male gorillas, for example, dwarf their female counterparts. But for most birds of prey, it's the opposite. Male bald eagles weight about 25 percent less than females.

Scientists aren't sure why there's such a size difference. One reason might be the way they divide up their nesting duties. Females take the lead in arranging the nesting material, so being bigger might help them take charge. Also, they spend longer incubating the eggs than males, so their size could intimidate would-be egg thieves.

If you're trying to tell male and female eagles apart, this size difference may help you—especially since both sexes have the same plumage patterns.

8. TO IDENTIFY THEM, LOOK AT THE WINGS.

A bald eagle flies across the water.
iStock

People often get excited about a big soaring bird and yell "It's an eagle!” just before it swoops closer and … oops, it's a vulture. Here's a handy identification tip. Bald eagles usually soar with their wings almost flat. On the other hand, the turkey vulture—another dark, soaring bird—holds its wings up in a shallow V shape called a dihedral. A lot of large hawks also soar with slightly raised wings.

9. THEY'RE COMEBACK KIDS.

Baby eagle chicks in a nest.
iStock

Before European settlers arrived, bald eagles were abundant across the U.S. But with settlement came habitat destruction, and the settlers viewed the eagles as competition for game and as a threat to livestock. So many eagles were killed that in 1940 Congress passed an act to protect the birds.

Unfortunately, another threat rose up at about that time. Starting after World War II, farmers and public health officials used an insecticide called DDT. The chemical worked well to eradicate mosquitos and agricultural pests—but as it traveled up the food chain, it began to heavily affect birds of prey. DDT made eagle eggshells too thin and caused the eggs to break. A 1963 survey found just 471 bald eagle pairs in the lower 48 states.

DDT was banned in the early 1970s, and conservationists began to breed bald eagles in captivity and reintroduce them in places across America. Luckily, this species made a spectacular recovery. Now the lower 48 states boast over 9700 nesting pairs.

10. THEY'RE UNIQUELY NORTH AMERICAN.

An African fish eagle flies over the water.
The African fish eagle is a relative of the North American bald eagle.
iStock

You've probably heard of America's other eagle: the golden eagle. This bird lives throughout much of the northern hemisphere. But the bald eagle is only found in North America. It lives across much of Canada and the U.S., as well as northern parts of Mexico.

Though it may be North American, the bald eagle has seven close relatives that are found throughout the world. They all belong to the genus Haliaeetus, which comes—pretty unimaginatively—from the Latin words for "sea" and "eagle." One relative, the African fish eagle, is a powerful symbol in its own right. It represents several countries; for example, it's the national symbol of Zambia, and graces the South Sudanese, Malawian, and Namibian coats of arms.

11. THEY'RE AERIAL DAREDEVILS.

A bald eagle carries a fish off in its talons.
iStock

It seems too weird to be true: While flying, bald eagles sometimes grab each other's feet and spin while plummeting to the Earth. Scientists aren't sure why they do this—perhaps it's a courtship ritual or a territorial battle. Usually, the pair will separate before hitting the ground (as seen in this remarkable set of photographs). But sometimes they hold tight and don't let go. These two male bald eagles locked talons and hit the ground with their feet still connected. One subsequently escaped and the other was treated for talon wounds.

12. THEIR EYES ARE AMAZING.

Close-up of a bald eagle's face.
iStock

What if you could close your eyes and still see? Besides the usual pair of eyelids, bald eagles have a see-through eyelid called a nictitating membrane. They can close this membrane to protect their eyes while their main eyelids remain open. The membrane also helps moisten and clean their eyes.

Eagles also have sharper vision than people, and their field of vision is wider. Plus, they can see ultraviolet light. Both of those things mean the expression "eagle eye" is spot-on.

13. THEY MIGRATE … SORT OF.

A bald eagle sits in a snowy tree.
iStock

If you're a bald eagle that nests in northern Canada, you'll probably head south for the winter to avoid the punishing cold. Many eagles fly south for the winter and return north for the summer—as do plenty of other bird species (and retired Canadians). But not all bald eagles migrate. Some of them, including individuals in New England and Canada's Maritime provinces, stick around all year. Whether or not a bird migrates depends on how old it is and how much food is available.

14. THEY CAN SWIM … SORT OF.

A bald eagle
iStock

There are several videos online—like the one above—that show a bald eagle swimming in the sea, rowing itself to shore with its huge wings. Eagles have hollow bones and fluffy down, so they can float pretty well. But why swim instead of soar? Sometimes, an eagle will swoop down and grab an especially weighty fish, then paddle it to shore to eat.

Note that the announcer in the video above says that the eagle's talons are "locked" on a fish that's too heavy to carry. In fact, those lockable talons are an urban legend.

nextArticle.image_alt|e
iStock
arrow
Animals
How Bats Protect Rare Books at This Portuguese Library
iStock
iStock

Visit the Joanina Library at the University of Coimbra in Portugal at night and you might think the building has a bat problem. It's true that common pipistrelle bats live there, occupying the space behind the bookshelves by day and swooping beneath the arched ceilings and in and out of windows once the sun goes down, but they're not a problem. As Smithsonian reports, the bats play a vital role in preserving the institution's manuscripts, so librarians are in no hurry to get rid of them.

The bats that live in the library don't damage the books and, because they're nocturnal, they usually don't bother the human guests. The much bigger danger to the collection is the insect population. Many bug species are known to gnaw on paper, which could be disastrous for the library's rare items that date from before the 19th century. The bats act as a natural form of pest control: At night, they feast on the insects that would otherwise feast on library books.

The Joanina Library is famous for being one of the most architecturally stunning libraries on earth. It was constructed before 1725, but when exactly the bats arrived is unknown. Librarians can say for sure they've been flapping around the halls since at least the 1800s.

Though bats have no reason to go after the materials, there is one threat they pose to the interior: falling feces. Librarians protect against this by covering their 18th-century tables with fabric made from animal skin at night and cleaning the floors of guano every morning.

[h/t Smithsonian]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios