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15 Astonishing Facts About Bats

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Roughly one in five mammal species is a bat. You may have heard of the famous vampire bats that feed on blood, but some lesser-known species use sonar to catch fish, scurry across the ground like mice, build their own tents, and even stick to sheer walls with suction cups. Let’s get face-to-face with some of the most bizarre bats in the world.

1. SOME BATS STICK TO VERTICAL WALLS.

If you want to attach something to a smooth vertical surface—a car window, maybe, or a slippery shower wall—you might use a suction cup. Disk-winged bats use them, too. They have special cups on their ankles and wrists that help them stick to smooth tropical leaves. This gives them a high, safe place to rest in the bustling tropical forest. Sucker-footed bats, meanwhile, hang on using wet adhesion—they ooze a liquid that helps them cling to a surface.

2. SOME CAN CATCH FISH.

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When bats hunt insects at night, they find their prey with an amazing sonar-like ability called echolocation—they make sounds that bounce off objects, then listen to the echoes for clues about what’s ahead. But the greater bulldog bat, which is named for its dog-like face, uses this sonar to catch fish. Flying above the water, it senses telltale ripples caused by the underwater movements of its prey. It skims the surface with its large feet and swiftly snatches a slippery meal. Here’s a video of this remarkable bat in action.

3. ONE SPECIES WEIGHS LESS THAN A PENNY.

Kitti’s hog-nosed bat is the world’s smallest bat—and, in fact, it’s in the running for the world’s smallest mammal. This animal is just a little over an inch (33 millimeters) long and weighs less than a penny. It’s also pretty unique: its ancestors split off from other bats a whopping 43 million years ago. Kitti’s hog-nosed bat is native to Burma and Thailand, where it’s vulnerable to habitat destruction.

4. SOME CONSTRUCT TENTS.

If you take a backwoods survival class, you’ll learn to build a shelter out of the natural material around you. And if you’re like most beginners, your first few shelters might fall down or let in too much rain. Shelter-building is a hard skill to master—but some bats have got it down. They gnaw the veins of a large tropical leaf, making it fold into a tent that protects them from rainfall and predators. One of these tent-making species is the Honduran white bat. As an added bonus, a group of these animals snuggling under their tent looks like a pile of marshmallows.

5. SOME CRAWL AROUND ON THE GROUND.

When a New Zealand lesser short-tailed bat is hungry, it hits the ground. It folds its wings up tight and uses them as forelegs as it scurries, mouse-like, across the forest floor in search of a snack. This bat’s diet is very diverse—it’ll eat nectar, pollen, berries, insects, and more. Here’s a video of lesser short-tailed bats searching for a meal.

6. THEY COME IN AMAZING PATTERNS.

A painted woolly bat. Image credit: Reeder D et al via Wikimedia Commons // CC BY 3.0

Bats aren’t just brown. The painted woolly bat of Southeast Asia is orange and black like a jack-o'-lantern. Indonesia’s stripe-faced fruit bat is also ready for Halloween with some spooky makeup. Then there’s the stunning pied bat; an inhabitant of central and western Africa, it has striking white blotches that make it look like a badger or a panda. These are just a few of the world’s many, many beautifully patterned bats.

7. THIS ONE BAT HAS FANTASTIC HAIR.

Native to sub-Saharan Africa, Chapin’s free-tailed bat has a wicked hairstyle. Females sport a small tuft of fur that sticks up, but males have much larger crests [PDF] that play a role in their courtship, and also just look cool.

8. SOME BATS SING LOVE SONGS.

Move over, nightingales. The males of several bat species woo their mates with tunes that are every bit as complex as those of songbirds. For instance, to construct a proper song, a Brazilian free-tailed bat needs to follow certain rules and patterns, but like a great improvisational musician, he also adds his own special style that marks him as unique.

How do bats learn these complicated songs? They pick them up from their parents. The greater sac-winged bat of Central and South America hones its singing skills as a baby. Like human kids, young sac-winged bats babble as they try to copy their dads’ sounds.

9. THIS BAT HAS A HORSE’S HEAD.

Bats have some truly bizarre faces, but one of the all-time weirdest belongs to the male hammer-headed fruit bat of equatorial Africa. Females of this species have a relatively ordinary foxlike head. But males have heads that are almost three times as large as a female’s. Their faces look even weirder from the front. Why that giant face and protruding lips? They help this bat make a unique honking call.

10. SOME BATS EAT SCORPIONS.

Adesert long-eared bat. Image credit: Charlotte Roemer via Wikimedia // CC BY-SA 3.0 

The desert long-eared bat chows down on scorpions—and doesn’t mind being stung in the face as it pounces on its prey. Native to parts of Africa, the Middle East, and Asia, this bat catches scorpions by attacking their heads. The scorpions vigorously defend themselves by stinging the bat on its face and body. Unperturbed, the bat dispatches its meals and carries them back to a roost. There, it gulps down every bit of a scorpion—even the stinger.

The desert long-eared bat isn’t fussy about which scorpion species it hunts. It’ll even chow down on the deathstalker, one of the few scorpions in the world whose sting is potentially deadly to humans.

11. SOME BATS POLLINATE FLOWERS.

Bees are famous for pollinating crops, and they help us grow such familiar foods as apples, pumpkins, and macadamia nuts. But bats are pollinators, too. Those huge Saguaro cacti of the U.S. southwest, for example, bloom in the evening to attract pollinating bats. And the agaves that give us tequila are also bat-pollinated; they make stinky flowers on tall stalks that open at night. Wild bananas rely on bats, too.

12. ONE BAT HAS A TONGUE THAT’S LONGER THAN ITS BODY.

The tube-lipped nectar bat’s tongue is a whopping 1.5 times the length of its body. This bat uses its monstrous tongue to reach tasty nectar that’s deep inside long-tubed flowers. When the tongue’s not in use, it’s stored in the bat’s chest, next to its heart.

13. SOME BATS ARE HUGE.

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Certain fruit-eating bats have a wingspan of over five feet. One of the largest is the golden-capped fruit bat of the Philippines. Named for its shock of blond “hair,” it can weigh more than two and a half pounds. It roosts in large numbers and dines on fruit such as figs. Deforestation and hunting, however, have put serious pressure on this batty behemoth.

14. MOTHS CAN JAM A BAT’S SONAR.

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Many insect-eating bats use echolocation to hunt down their flying prey. But some moths fight back. They rub their genitals together to make sounds that interfere with a bat’s sonar. Confused, the hungry bats zero in on the wrong location and bite at empty air.

This acoustic warfare isn’t just limited to bats vs. moths. Researchers have found that Mexican free-tailed bats seem to jam each other’s signals when they’re competing for prey.

15. THIS BAT’S FACE DOESN’T EVEN LOOK LIKE A FACE.

We’ve established that bats have weird faces. Some bats have yellow tube-shaped nostrils. Some look like their faces collapsed inward. Some are mostly made of ears. But let’s end this list with one of the most extraordinary-looking species. Bourret's horseshoe bat, which lives in Southeast Asia, has a face that suggests an origami project gone wrong. Why the long nose? It’s perfectly shaped to help focus the bat’s sonar.

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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Scientists Think They Know How Whales Got So Big
May 24, 2017
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It can be difficult to understand how enormous the blue whale—the largest animal to ever exist—really is. The mammal can measure up to 105 feet long, have a tongue that can weigh as much as an elephant, and have a massive, golf cart–sized heart powering a 200-ton frame. But while the blue whale might currently be the Andre the Giant of the sea, it wasn’t always so imposing.

For the majority of the 30 million years that baleen whales (the blue whale is one) have occupied the Earth, the mammals usually topped off at roughly 30 feet in length. It wasn’t until about 3 million years ago that the clade of whales experienced an evolutionary growth spurt, tripling in size. And scientists haven’t had any concrete idea why, Wired reports.

A study published in the journal Proceedings of the Royal Society B might help change that. Researchers examined fossil records and studied phylogenetic models (evolutionary relationships) among baleen whales, and found some evidence that climate change may have been the catalyst for turning the large animals into behemoths.

As the ice ages wore on and oceans were receiving nutrient-rich runoff, the whales encountered an increasing number of krill—the small, shrimp-like creatures that provided a food source—resulting from upwelling waters. The more they ate, the more they grew, and their bodies adapted over time. Their mouths grew larger and their fat stores increased, helping them to fuel longer migrations to additional food-enriched areas. Today blue whales eat up to four tons of krill every day.

If climate change set the ancestors of the blue whale on the path to its enormous size today, the study invites the question of what it might do to them in the future. Changes in ocean currents or temperature could alter the amount of available nutrients to whales, cutting off their food supply. With demand for whale oil in the 1900s having already dented their numbers, scientists are hoping that further shifts in their oceanic ecosystem won’t relegate them to history.

[h/t Wired]

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