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15 Fish With Amazing Talents

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istock

As these marvelous swimmers demonstrate, schools of fish definitely have the best talent shows.

1. Clownfish Regularly Change Sex.

Scientifically known as “sequential hermaphrodites,” all clownfish are initially born male. However, gender-swapping is rampant. As adults, clownfish develop complex hierarchies headed by a dominant female. Should she die off, one male will transform himself into the next alpha-female, continuing this strange life cycle.

2. Peacock Flounders are Masters of Disguise.

Flat fish don’t get much respect, but maybe they should. Pigment-altering skin cells enable the peacock flounder to radically change its color scheme within seconds. By comparison, chameleons generally take several minutes to even slightly modify their hues. Point goes to the flounder.

3. Clown Loaches Can Defend Themselves with Facial Spikes.

They’re a hit with aquarium enthusiasts, but any predator can tell you that clown loaches make terrible dinner guests. These colorful Indonesian fish have movable spines beneath their eyes which, when raised, make them exceedingly difficult to swallow.

4. Tiger Fish Can Snag Birds in Midair.

With their huge, razor-sharp teeth, African tiger fish look like they mean business. Scarier still, one specimen was recently recorded leaping clear out of a freshwater lake and engulfing an unfortunate bird just above the surface. You have to respect that kind of athletic ability.

5. Parrot Fish Help Build Beaches.

Have you ever kicked back on one of Hawaii’s gorgeous white beaches? Some of that sand was probably fish waste. Parrot fish eat various organisms that live on coral reefs. While feeding, they inevitably wind up swallowing chunks of rock-hard coral, a side-dish these critters can’t digest. Such pieces get broken down and pass through their systems as freshly-made sand.

6. Archerfish Are Expert Marksmen.

It’s like the world’s deadliest squirt gun. Archerfish have one of nature’s most oddly specific hunting strategies: namely, spraying hapless insects with a controlled jet of water. The victim—usually perched on an overhanging plant limb—falls directly into the archerfish’s eager jaws.

7. Sawfish Can Sense Beating Hearts.

Electroreceptors on a sawfish’s toothy snout allow it to detect even the faintest heartbeats. This really comes in handy, considering that preferred menu options (crabs, shrimp, smaller fish, etc.) regularly hide out under several inches of sand.

8. Sockeye Salmon Use Magnetic Fields to Navigate.

These salmon famously migrate for thousands of miles and return to the same streams in which they hatched. How can they pull off this amazing feat without a GPS? By picking up on tiny variations in the earth’s magnetic field. No two streams, after all, give off exactly the same magnetic signature.

9. Hagfish Fend off Predators With a Cloud of Slime.

They may look like pushovers, but these scavengers know how to protect themselves. The hagfish’s unique skin glands release a thick, fibrous haze of gunk that clogs jaws and jams gills to teach naïve attackers a lesson they won’t soon forget.

10. Antarctic Tooth Fish Have Freeze-Resistant Blood Streams.

Swimming through icy polar depths (which can dip below -2º Celsius) becomes child’s play when there’s an all-natural antifreeze coursing through your blood.

11. Gobies Go Rock Climbing.

Most fish would see trying to scale a waterfall as an impossible task. Luckily, few fish enjoy extreme sports more than rock-climbing gobies of Hawaii. When gobies need to venture upstream through swift mountain waters, waterfalls and sheer rock faces are no hurdle: The fish use their incredibly strong mouths and a unique sucker appendage on their bellies to grab onto rocks and gradually inch their way up to more hospitable territory.

12. Cookie Cutter Sharks Used to Re-Route Nuclear Submarines.

Evolution has equipped these guys to take circular chunks out of passing animals. And, as the U.S. Navy found out, the 22-inch sharks aren’t exactly finicky eaters. During the 1970s, cookie-cutters wreaked havoc on unsuspecting subs by chomping through sensitive cables and rubber sonar equipment, forcing these vessels to return to base.

13. Black Swallowers Really Live Up to Their Names.

Wikimedia Commons // Public Domain

Generous jaws and a uniquely designed stomach enable these 10-inch predators to gulp down live meals that are twice their own length and 10 times as massive.

14. Plainfin Midshipmen Hum to Attract Mates.

Wikimedia Commons // Public Domain

We don’t normally associate fish with vocalization, but some amorous males of this species, also known as “California singing fish,” emit hour-long humming noises to arouse potential mates (and angry grunts whenever a competitor zeroes in).

15. Mudskippers Climb Trees.

What’s even more amazing than a fish crawling around on land? A fish crawling up a tree. As adaptable mangrove swamp denizens, mudskippers periodically exit the water and walk over patches of mud. They’re also known to scale tree branches from time to time. Next up on their to-do lists: building treehouses.

All images courtesy of iStock unless noted otherwise.

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iStock // Ekaterina Minaeva
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technology
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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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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iStock
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Health
200 Health Experts Call for Ban on Two Antibacterial Chemicals
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iStock

In September 2016, the U.S. Food and Drug Administration (FDA) issued a ban on antibacterial soap and body wash. But a large collective of scientists and medical professionals says the agency should have done more to stop the spread of harmful chemicals into our bodies and environment, most notably the antimicrobials triclosan and triclocarban. They published their recommendations in the journal Environmental Health Perspectives.

The 2016 report from the FDA concluded that 19 of the most commonly used antimicrobial ingredients are no more effective than ordinary soap and water, and forbade their use in soap and body wash.

"Customers may think added antimicrobials are a way to reduce infections, but in most products there is no evidence that they do," Ted Schettler, science director of the Science and Environmental Health Network, said in a statement.

Studies have shown that these chemicals may actually do more harm than good. They don't keep us from getting sick, but they can contribute to the development of antibiotic-resistant bacteria, also known as superbugs. Triclosan and triclocarban can also damage our hormones and immune systems.

And while they may no longer be appearing on our bathroom sinks or shower shelves, they're still all around us. They've leached into the environment from years of use. They're also still being added to a staggering array of consumer products, as companies create "antibacterial" clothing, toys, yoga mats, paint, food storage containers, electronics, doorknobs, and countertops.

The authors of the new consensus statement say it's time for that to stop.

"We must develop better alternatives and prevent unneeded exposures to antimicrobial chemicals," Rolf Haden of the University of Arizona said in the statement. Haden researches where mass-produced chemicals wind up in the environment.

The statement notes that many manufacturers have simply replaced the banned chemicals with others. "I was happy that the FDA finally acted to remove these chemicals from soaps," said Arlene Blum, executive director of the Green Science Policy Institute. "But I was dismayed to discover at my local drugstore that most products now contain substitutes that may be worse."

Blum, Haden, Schettler, and their colleagues "urge scientists, governments, chemical and product manufacturers, purchasing organizations, retailers, and consumers" to avoid antimicrobial chemicals outside of medical settings. "Where antimicrobials are necessary," they write, we should "use safer alternatives that are not persistent and pose no risk to humans or ecosystems."

They recommend that manufacturers label any products containing antimicrobial chemicals so that consumers can avoid them, and they call for further research into the impacts of these compounds on us and our planet.

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