Why Do Bats Hang Upside Down?

iStock.com/CraigRJD
iStock.com/CraigRJD

Stefan Pociask:

The age-old question of upside down bats. Yes, it is awfully weird that there is an animal—a mammal even—that hangs upside down. Sure, some monkeys do it when they're just monkeying around. And a few other tree climbers, like margays, hang upside down if they are reaching for something or—again, like the margay cat—may actually even hunt that way ... But bats are the only animals that actually spend most of their time hanging upside down: feeding this way, raising their young this way, and, yes, sleeping or roosting this way.

There is actually a very good and sensible reason why they do this: They have to hang upside down so that they can fly.

First off, we have to acknowledge that bats are not birds, nor are they insects. These are the other two animals that have true powered flight (as opposed to gliding). The difference between bat flight and bird or insect flight is weight—specifically, the ratio of weight to lift-capacity of the wings. If you walk up to a bird or insect, most species will be able to fly right up into the air from a motionless position, and do it quickly.

Bats, on the other hand (or, other wing), can’t do that. They have a lot of difficulty taking off from the ground (not that they can’t do it ... it’s just more difficult). Insects and birds often actually jump into the air to give them a start in the right direction, then their powerful wings take them up, up, and away.

Birds have hollow bones; bats don’t. Insects are made of lightweight chitin or soft, light tissue; bats aren’t. And bats don’t have what you could call "powerful" wings. These amazing creatures are mammals, after all. The only flying mammals. Nature found a way to evolve such an unlikely thing as a flying mammal, so some compromises had to be made. Bats, once airborne, manage perfectly well in the air, and can literally fly circles around most birds in flight. The problem is in first getting off the ground.

To compensate for the extra weight that mammals must have, to compensate for the problem of getting off the ground, evolution found another way for bats to transition from being motionless to immediately being able to fly when necessary. Evolution said, “How about if we drop them from above? That way they are immediately in the air, and all they need to do is start flapping."

It was a great idea, as it turns out. Except bat feet aren’t any good for perching on a branch. They are mammals, not birds, so their musculature, their bones, and their tendons are set up in a completely different way. When a bird squats down on a branch, their tendons actually lock their toes into an even tighter grip on the perch. It happens automatically. That’s part of being a bird, and is universal. That’s why they don’t fall off in their sleep.

Bats, as mammals, are set up differently. Therefore, to compensate for that fact, nature said, “How about if we have them hang upside down? That way, their tendons will actually pull their toes closed, just like a bird does from the opposite direction.” So that’s what evolved. Bats hang from the bottom of something, and all they have to do is "let go" and they are instantly flying. In fact, with this gravity-assist method, they can achieve instant flight even faster than birds, who have to work against gravity.

Side note: In case you were wondering how bats poop and pee while upside down ... First off, pooping is no big deal. Bat poop looks like tiny grains of rice; if they are hanging, it just falls to the floor of the bat cave as guano. Pee, however ... well, they have that covered too. They just “hold it” until they are flying.

So there you go. Bats sleep hanging upside down because they are mammals and can’t take off into the air like birds can (at least not without difficulty). But, if they're hanging, all they do is let go.

Makes total sense, right?

Now, having said all that about upside down bats, I must mention the following: Not all of the 1240-plus species of bats do hang upside down. There are exceptions—about six of them, within two different families. One is in South America (Thyropteridae) and the other is in Madagascar (Myzopodidae). The Myzopodidae, which includes just one species, is exceedingly rare.

So it turns out that these bats roost inside the tubes of young, unfurled banana leaves and other similar large leaves. When they attach themselves to the inside of this rolled leaf, they do it head-up. The problem with living inside of rolled-up leaves is that within a few days, these leaves will continue growing, and eventually open up. Whenever that happens, the whole group of bats has to pick up and move to another home. Over and over again. All six of these species of rare bats have a suction cup on each wrist and ankle, and they use these to attach to the smooth surface of the inside of the leaf tube. Evolution: the more you learn, the more amazing it becomes.

This post originally appeared on Quora. Click here to view.

Why Are Poinsettias Associated with Christmas?

iStock
iStock

Certain Christmas traditions never seem to go out of style. Along with wreaths, gingerbread cookies, and reruns of A Christmas Story sits the poinsettia, a red-tinged leafy arrangement that’s become synonymous with the holiday. Upwards of 100 million of them are sold in the six weeks before December 25.

Why do people associate the potted plant with seasonal cheer? Chalk it up to some brilliant marketing.

In 1900, a German immigrant named Albert Ecke was planning to move his family to Fiji. Along the way, they became enamored of the beautiful sights found in Los Angeles—specifically, the wild-growing poinsettia, which was named after Joel Roberts Poinsett, the U.S.-Mexican ambassador who first brought it to the States in 1828. Ecke saw the appeal of the plant’s bright red leaves that blossomed in winter (it’s not actually a flower, despite the common assumption) and began marketing it from roadside stands to local growers as "the Christmas plant."

The response was so strong that poinsettias became the Ecke family business, with their crop making up more than 90 percent of all poinsettias sold throughout most of the 20th century: Ecke, his son Paul, and Paul’s son, Paul Jr., offered a unique single-stem arrangement that stood up to shipping, which their competitors couldn’t duplicate. When Paul III took over the business in the 1960s, he began sending arrangements to television networks for use during their holiday specials. In a priceless bit of advertising, stars like Ronald Reagan, Dinah Shore, and Bob Hope were sharing screen time with the plant, leading millions of Americans to associate it with the holiday.

While the Ecke single-stem secret was eventually cracked by other florists—it involved grafting two stems to make one—and their market share dwindled, their innovative marketing ensured that the poinsettia would forever be linked to Christmas.

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Why Does Santa Claus Live at the North Pole?

allanswart/iStock via Getty Images
allanswart/iStock via Getty Images

As children settle in for a restless night’s sleep this Christmas Eve, they’ll no doubt be picturing Santa Claus on his way from the snowy ’scapes of the North Pole to deliver them Star Wars LEGO sets, Frozen 2 dolls, and everything else on their wish list. They picture Santa at the North Pole, of course, because they’ve seen him living there in numerous Christmas movies, books, and television specials, from perennial Rankin/Bass programs to more modern classics like 2003’s Elf.

While it might seem a little more magical if we told you that nobody really knows why Santa lives there, there is a relatively traceable paper trail: The first known reference to Santa’s North Pole residence is in an 1866 cartoon from Harper’s Weekly.

According to Smithsonian.com, famed political cartoonist Thomas Nast—who was also responsible for establishing the donkey and elephant as the symbols for the Democratic and Republican parties, respectively—first started creating Harper’s Weekly Christmas cartoons as Union propaganda for the Civil War in January 1863. Borrowing imagery from Clement Clarke Moore’s (alleged) 1823 poem “A Visit From St. Nicholas” (which you’d probably recognize as “’Twas the Night Before Christmas”), Nast developed the white-bearded, rosy-cheeked, all-around jolly guy that we know today, and showed him passing out gifts to Union soldiers, climbing into a chimney as a soldier’s wife prays, and more.

harper's weekly santa claus at camp by thomas nast
Thomas Nast, Harris Brisbane Dick Fund, Wikimedia Commons // Public Domain

The cartoons became so popular that Nast branched out from his source material and began inventing his own details to add to Saint Nick—like where he’s from, for example. A December 29, 1866 issue of Harper’s Weekly debuted a multi-image cartoon titled “Santa Claus and His Works,” which includes a small inscription along the circular border that reads Santa Claussville, N.P. According to The New York Times, we don’t know exactly why Nast chose the North Pole (or if it was even his own idea), but there are a few reasons it made sense for the time period.

For one, Santa Claus was already widely associated with snow because most of the publishing companies producing Christmas cards and other content were located in New England, where it actually snows around Christmas. Furthermore, the 1840s and 1850s were partly characterized by high-profile—and ill-fated, in the Franklin expedition's case—attempts to explore the Arctic, and the public was generally interested in the mysterious, poorly-charted region. Because the Pole was unoccupied, Santa and his elves could toil the year away without interference from prying eyes; and, because it was unclaimed, Santa could remain a bastion of benevolence for every nation.

merry old santa claus by thomas nast
"Merry Old Santa Claus," perhaps Nast's most famous illustration of Santa, from the January 1, 1881 edition of Harper's Weekly.
Thomas Nast, Wikimedia Commons // Public Domain

Though we’ll likely never know Nast’s personal rationale behind placing Santa Claus in the North Pole, one thing’s for sure: At this point, it’s hard to imagine him living anywhere else. It’s also hard to imagine him riding a broom, wielding a gun, or smoking cigarettes (find out the stories behind those early Santas here).

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