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7 Animals That Eat One Food Almost Exclusively

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Occasionally, deep in the bliss of a fourth of fifth or sixth slice of pizza, you might remark, "I could eat pizza for the rest of my life." But most of us aren't dedicated enough to forgo the bounty of modern cuisine for just one foodstuff—not even pizza. Most wild animals opt for a buffet style approach, too; after all, being picky about what to eat could mean starvation. But a few animals are able to make the equivalent of the pizza pledge. Here are a few of them. 

1. Egg-eating snakes

These snakes eat only amniotic eggs, which have a shell and a number of embryonic membranes. The snakes have bones, called hypapophyses, which are large and sharp enough to penetrate egg shells. After the snake cracks the shell, the yolk proceeds on to the stomach, and the snake regurgitates the shell. There are 11 kinds of egg-eating snakes in Africa and one really rare species found in India.

2. Koalas

The vast majority of a koala's diet consists of the leaves from the eucalyptus plant. There are some 600 species of eucalyptus available to the koala, but the koala only eats the leaves of about three dozen varieties. The fibrous leaves, which are low in nutritional value, are also difficult to digest; the koala saves its energy by sleeping or resting up to 22 hours a day.

3. Snail kite

A kite is a kind of bird, and a snail kite is a kind of bird that eats apple snails almost exclusively. When apple snails are scarce, it will occasionally poke around at other animals (including small turtles and crayfish) found in its habitat, which spans much of South America and parts of Florida and the Caribbean.

4. Giant pandas

Some 99 percent of a giant panda's diet is comprised of the leaves, shoots, and stems of bamboo. Like eucalyptus, bamboo doesn't have a lot of nutritional value, so pandas have to eat 26 to 83 pounds of the tough, fibrous plant a day. China's giant pandas are from the animal order Carnivora, though, and so they occasionally will eat small rodents. (And in captivity, according to the Smithsonian National Zoo, the bears eat "bamboo, sugar cane, rice gruel, a special high-fiber biscuit, carrots, apples, and sweet potatoes.")

5. Monarch caterpillars

Monarch butterflies, of course, eat nectar. But as caterpillars, they only eat the leaves of the toxic milkweed plant, which makes the caterpillars—and the adult butterflies—poisonous to animals.

6. Black-footed ferrets

The endangered black-footed ferret lives in the Western United States and eats mostly prairie dogs—more than 100 a year. The ferrets hunt them in their burrows and live in the abandoned digs. Occasionally, when a prairie dog isn't around (roughly nine percent of the time), the black-footed ferret will chow down on squirrels and mice.

7. Pen-tailed treeshrews

Wikimedia Commons

The pen-tailed treeshrew of Thailand and Indonesia only drinks the naturally fermented nectar of the bertam palm, which has an alcohol content of 3.8 percent (the equivalent of a can of light lager). The little creature drinks the equivalent of 10 to 12 cans of beer a night. Despite the fact that the animals are drinking an amount of alcohol that would be dangerous for most mammals, they don't show any signs of intoxication.

All images courtesy of iStock unless otherwise noted.

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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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Name the Author Based on the Character
May 23, 2017
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