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Moth (left, iStock); Butterfly (right, iStock)

How to Tell the Difference Between 7 Pairs of Commonly Confused Animals

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Moth (left, iStock); Butterfly (right, iStock)

It’s hard to tell some animal species apart. Is that a jaguar glaring balefully at you from the shadows, or a leopard? A lizard slithering on the ground, or a salamander? Fear not—we’ve got you covered. Here are some (almost) fool-proof methods for distinguishing between seven pairs of critters.


This one might seem like a no-brainer. Most people think of butterflies as colorful garden visitors, whereas those drab moths only emerge at night to bonk against your porch light. But not so fast.

Moths and butterflies belong to the scientific order Lepidoptera—and it’s a huge, spectacularly diverse group, with tons of species that defy your expectations. Some moths fly during the day, hovering at flowers and drinking nectar. Moths can be spectacularly colorful, like this Madagascar sunset moth. And there are plenty of dull-colored butterflies, such as the brown-grey common ringlet and the grayish Avalon hairstreak.

So how can you tell them apart? One of the best methods is to look at the antennae (those long appendages that stick out from the head). With some exceptions, butterflies have a thickened part at the end of the antennae. Moth antennae, on the other hand, are usually slender or feathery and taper to a point.


Bottlenose Dolphin (left, Wikimedia Commons); Harbor Porpoise (right, Wikimedia Commons)

You might have heard people use these words interchangeably, but dolphins and porpoises are very different. First off, there are way more dolphins than porpoises. The ocean dolphin family Delphinidae contains approximately 32 species, including bottlenose dolphins (like Flipper) and killer whales (like Shamu). But there are only about seven species in the porpoise family Phocoenidae. And there may soon be just six—one species, the panda-like vaquita, is nearly extinct.

In general, porpoises and dolphins have different body shapes. Porpoises tend to have rounded faces, chunky bodies, and triangular dorsal (back) fins. Many dolphins, on the other hand, have pointy faces, slender bodies, and curved dorsal fins. But there are exceptions—Risso’s dolphins, for example, have blunt heads.

Another distinguishing feature is tooth shape. Porpoise teeth are spade-shaped and dolphin teeth are cone-shaped. But that’s pretty hard to see unless you stick your head in their mouths.


Sheep (left, iStock); Goat (right, iStock)

Domestic sheep and goats are both cloven-hoofed, four-legged critters with soft muzzles and really strange eyes. Here’s an easy way to tell them apart: look at the tail. Goats usually hold their tails up, whereas sheep tails hang down.

They also have different eating habits. Sheep, like cows, are grazers—they move across a pasture like fluffy vacuum cleaners, scarfing down vegetation close to the ground. Goats, on the other hand, are browsers. They pick and choose their bites from plants that are a little higher up. They’ll even climb trees for choice morsels.


Lizard (left, iStock); Salamander (right, iStock)

Lizards and salamanders look a lot alike. They have long bodies and tails, and they generally crawl around on four legs. But looks can be deceiving. Lizards and salamanders are only distantly related; in fact, lizards are closer cousins to humans than they are to salamanders.

Lizards are reptiles, like snakes and turtles. Salamanders, on the other hand, are amphibians, like frogs. Look closely and you’ll see major differences: lizards have claws on their feet, but salamanders don't (although there are one or two exceptions). Salamanders also lack scales; their skin is often smooth, moist, and slimy. Many species lack internal lungs, so their skin functions as an inside-out lung.


Hedgehog (left, iStock); Porcupine (right, iStock)

Let’s start with the basics: hedgehogs and porcupines are spiny. Those spines are made of special hardened hairs with hollow centers. But that’s about all these critters have in common. They aren’t closely related, and they evolved spines separately. And here’s the strange part: there are two groups of porcupine species—New World and Old World types—and they each evolved spines on their own. It’s just a useful evolutionary strategy!

Hedgehogs’ closest relatives resemble spineless hedgehogs; they’re mammals called gymnures and moonrats. Porcupines, however, belong to the order Rodentia—they are rodents. They may not look very rodent-y, but check out their big front teeth.

Porcupines use those chisel-like teeth to eat vegetation. Hedgehogs, on the other hand, have pointy teeth and snouts, and they’re omnivores, chowing down on frogs, insects, fruit, and more.

Hedgehog species inhabit parts of Europe, Africa, and Asia, but they’re not found in North and South America—so if you see a spiky animal in the New World, it’s a porcupine.


Saltwater crocodile (left, Wikimedia Commons); American alligator (right, Wikimedia Commons)

Alligators and crocodiles have a similar appearance, so it’s not surprising that they’re related: They belong to the order Crocodilia. One major difference is their salt tolerance. Crocodiles have special glands that help them excrete excess salt, so they’re comfortable in saltwater habitats such as coastal mangrove swamps. In alligators, those salt glands aren’t as well-developed, so gators are more likely to be found in freshwater.

Another difference is the shape of their heads. Crocodiles have longer V-shaped jaws, and alligator snouts are rounded and U-shaped. But there are exceptions; for example, the mugger crocodile of India and the surrounding region has a rounded snout like an alligator. Note that there are a couple of other members in the order Crocodilia that have EXTREMELY narrow snouts—the weird-looking false gharial and the even weirder-looking gharial.

Here’s another identification tip: take a look at the teeth. In crocodiles, the fourth tooth on the lower jaw sticks out, overlapping with the upper jaw and making the mouth look like a jigsaw puzzle gone horribly wrong.


Leopard (left, Wikimedia Commons); Jaguar (right, Wikimedia Commons)

They’re both big cats, and they’re both speckled. But if you see a jaguar or leopard in the wild, it’s easy to figure out the species, because they live on separate continents. Leopards inhabit parts of Africa and Asia, and jaguars are found in South and Central America, as well as occasionally the southwestern United States.

Here are a few other ways to distinguish them. Both cats have clusters of dark spots on their fur, but jaguars have smaller spots inside each cluster. Leopards are also smaller and more slender than jaguars, and their tails are longer. You probably won’t need any of these tips, though, because these animals are notoriously secretive and hard to find.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

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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Creative Bar Owners in India Build Maze to Skirt New Liquor Laws
June 20, 2017
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Facing a complicated legal maze, a bar in the southern Indian state of Kerala decided to construct a real one to stay in business, according to The Times of India. Aiswarya Bar, a watering hole that sits around 500 feet from a national highway, was threatened in 2016 after India's Supreme Court banned alcohol sales within 1640 feet of state and country-wide expressways to curb drunk driving. Instead of moving or ceasing operation, Aiswarya Bar's proprietors got creative: They used prefabricated concrete to construct a convoluted pathway outside the entrance, which more than tripled the distance from car to bar.

Aiswarya Bar's unorthodox solution technically adhered to the law, so members of the State Excise Administration—which regulates commodities including alcohol—initially seemed to accept the plan.

"We do [not] measure the aerial distance but only the walking distance," a representative told The Times of India. "However, they will be fined for altering the entrance."

Follow-up reports, though, indicate that the bar isn't in the clear quite yet. Other officials reportedly want to measure the distance between the bar and the highway, and not the length of the road to the bar itself.

Amid all the bureaucratic drama, Aiswarya Bar has gained global fame for both metaphorically and literally circumnavigating the law. But as a whole, liquor-serving establishments in India are facing tough times: As Quartz reports, the alcohol ban—which ordered bars, hotels, and pubs along highways to cancel their liquor licenses by April 1, 2017—has resulted in heavy financial losses, and the estimated loss of over 1 million jobs. Aiswarya Bar's owner, who until recently operated as many as nine local bars, is just one of many afflicted entrepreneurs.

Some state governments, which receive a large portion of their total revenue from liquor sales, are now attempting to downgrade the status of their state and national highways. To continue selling liquor in roadside establishments, they're rechristening thoroughfares as "urban roads," "district roads," and "local authority roads." So far, the jury's still out on whether Kerala—the notoriously heavy-drinking state in which Aiswarya Bar is located—will become one of them.

[h/t The Times of India]