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8 Animals That Get Their Color From Food

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Charlie and the Chocolate Factory gives new meaning to “you are what you eat.” In the classic kids’ book, a girl named Violet Beauregarde chews some experimental blueberry-flavored gum—and it turns her blueberry-blue. But for some animals, that’s not too far from the truth: they get their colors from the food they eat. Here are eight critters that get their hues from their diet, plus two honorable mentions: a bird that’s shinier when it eats bugs, and a garden plant that switches between pink and blue.

1. BLUE-FOOTED BOOBIES

Native to warm waters of the eastern Pacific, blue-footed boobies (above) have, well, bright blue feet. They use this fancy footwear to attract mates via an awkward dance. The blue color comes directly from carotenoid pigments in their fishy diet, and healthier birds can afford to expend more pigment to intensify their foot coloration. So, a bird with brighter feet is a more attractive partner. 

2. EASTERN EMERALD ELYSIAS

Karen N. Pelletreau et al. via Wikimedia // CC BY 4.0

Its name is straight out of a fantasy novel, and that’s not even the coolest thing about this marine slug-like animal. The eastern emerald elysia has turned itself, at least in part, into a plant. It’s green, it’s shaped almost exactly like a leaf, and it can do something that animals usually can’t do: make food from the sun.

Plants are green because their cells have special green parts called chloroplasts that make energy from the sun. When the eastern emerald elysia eats some algae, it adds insult to injury by stealing the algae’s chloroplasts. Then it basks in the sunlight and absorbs the food that the chloroplasts make. It’s able to keep these stolen parts functioning for nearly a year—enough time so that it may never need to eat algae again.

3. SALMON

Salmon flesh has such a lovely hue that we call it, well, salmon pink. These fish get their color from the small shellfish they eat. Farmed salmon are fed natural or synthetic pigments so that their meat retains this familiar tint.

4. FLAMINGOS

Everyone knows that flamingos are pink and bluebirds are blue, right? Well, not really: Flamingos are definitely pink, but bluebirds’ blue color is an illusion.

Birds have different ways of looking colorful. A bluebird’s feathers have special structures that break up light and reflect just the blue parts. This makes them look blue—but only when light is hitting them in just the right way. If you take a bluebird feather and shine a light behind it, the feather will appear brown. The same is true of most other blue and green birds, from blue jays to green parrots.

Flamingos, on the other hand, have feathers that stay pink no matter which way you look at them. That’s because they’re full of pink-red pigments called carotenoids—carrots are orange because they contain a type of carotenoid. Flamingos get this pink stuff from the shrimp that they eat. If they don’t consume the right food, they’ll turn grayer. Zookeepers have to feed their flamingos food with the right pigments to keep them rosy.

5. GOLDFINCHES

Many other birds get their hues from carotenoid pigments. That’s true of American goldfinches, which are blazing yellow in breeding season. Female goldfinches size up males based on the vibrancy of their yellow: Brighter males are healthier and have better diets, so they’re more attractive.

6. CEDAR WAXWINGS

Cedar waxwings are small, sleek songbirds. Their tails usually have yellow tips—but some have red tails, and it’s all our fault.

Cedar waxwings are native to North America, and they love eating berries. A few decades ago, people brought Asian honeysuckle varieties to North America. These plants spread throughout the forests, and they produce big red berries that are impossible for a hungry waxwing to resist. The berries are rich in a reddish pigment that builds up in waxwing tails, turning them from yellow to orange.

7. NUDIBRANCHS

Related to snails, nudibranchs live in the ocean, and they’re mind-blowingly colorful. Really: feast your eyes on these hues. They’re so colorful, in fact, that there’s a blog matching different species to David Bowie’s outfits.

Many nudibranchs get their bright colors from their prey. One species, the red sponge dorid, is bright red and probably gets its pigment from the red sponges it eats. This has the added benefit of giving the red sponge dorid some amazing camouflage when it’s crawling on its spongy food.

8. FRILLED DRAGONS

Remember that scene in Jurassic Park when a neck-frilled dinosaur terrifies the hapless hacker Dennis Nedry, then spits poison on him? The movie’s creators got their inspiration from Australia and New Guinea’s frilled dragons—also known as frill-necked lizards. These remarkable reptiles flare their huge frills when they’re scared, or as part of territorial or courtship displays.

Frilled dragons’ frills come in different colors, from red to orange to yellow. The colors depend on their geographical location—and the variation is probably because of the different amounts of pigment in their prey.

HONORABLE MENTION #1: HUMMINGBIRDS.

Many hummingbirds have shiny, iridescent patches of feathers. These hues don’t come from their diet; they’re the result of specially structured feathers that reflect light in amazing ways. But even though hummingbirds don’t get their color directly from their food, their diet has a strong influence on how shiny and bright they’ll be. 

Anna’s hummingbirds are tiny, fast-moving birds that live along the Pacific Coast of North America. Their foreheads and chins are iridescent red-purple. When they’re staking out territory, they stick up these feathers and enthusiastically show them off. To keep up their high-energy lifestyles, these birds eat sugary flower nectar. But there’s one problem with this sweet diet: Hummingbirds need protein to make their shiny feathers, and there’s not a lot of protein in nectar. Another option is to catch and eat insects, but this takes a LOT of energy. Scientists have found that Anna’s hummingbirds on higher-protein diets have shinier, redder crowns.

HONORABLE MENTION #2: HYDRANGEAS

Plants can also change color depending on their diets. Hydrangeas are familiar garden flowers, and they’re like living mood rings. If a hydrangea plant is absorbing aluminum from the soil, it turns bubblegum pink. In the absence of aluminum, it’s cotton candy blue. Gardeners adjust the colors by tweaking the soil pH—acidic soil promotes blue colors and basic promotes pinks.

All photos courtesy iStock unless otherwise noted.

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iStock // Ekaterina Minaeva
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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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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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