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Universal Images Group via Getty Images
Universal Images Group via Getty Images

The Sound of Running Water Puts Beavers in the Mood to Build

Universal Images Group via Getty Images
Universal Images Group via Getty Images

From the outside, a beaver dam looks like a heap of sticks, but a closer look reveals the insane amount of effort and detail that goes into building each structure. At a rate of five feet per day, beavers use mud, sticks, and rocks to construct the multi-chamber, watertight dams that hold their families and store their food. 

In the 1960s, Swedish biologist Lars Wilsson wanted to know if this industrious behavior was learned or innate. He decided to capture four adult beavers with the intention of raising them in different habitats. Some were kept in an outdoor enclosure and others in a glass-walled terrarium indoors. 

When a new generation of beavers was born, he chose a few of them to raise in isolation in order to study which of their behaviors were instinctual. He discovered that when released into running water, the young beavers built near perfect examples of dams on their first try. Wilsson then tried a different experiment where he placed the beavers in still or very slow-moving water. The subjects responded by burying themselves in the mud and making no attempts to build. 

It was only when Wilsson played them the sounds of running water through a speaker that their instincts kicked in. Suddenly the beavers were compelled to start building over the speaker, convinced that it was the source of the leak. When the sound was played for them through a loudspeaker on concrete, the beavers still built their dam over the dry floor. Even when presented with a clear pipe that showed water (silently) escaping through their dam and a speaker that played them the sound of running water, they chose to build over the speaker and ignore the clearly visible leak. 

This instinctive quirk makes beavers easy for people to manipulate. Instead of demolishing the dams that overflow river banks and damage property, a special, silent outflow pipe can be installed that diverts the water under the beavers’ radar. If blocking the sound of the pipe is impossible, people will sometimes make small holes in the dam around the pipe, which the beavers will innately plug up instead. For some reason, all those wicked dam-building skills now seem a lot less intimidating. 

[h/t: io9]

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Animals
Slow Motion Is the Only Way to Appreciate a Chameleon’s Lightning-Fast Tongue
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From the unusual way they walk, to their ability to change color, the evolutionary adaptations of chameleons are pretty bizarre, and some of them remain mysterious even to scientists. Their super-powered tongues, for instance, can dart out so quickly that the movement can barely be seen with the naked eye. But modern high-speed cameras have enabled researchers at the University of South Dakota to observe this appendage at work like never before. The video below, shared over at The Kid Should See This, includes some of that groundbreaking footage, and it's pretty amazing to watch.

Shooting at 3000 frames per second, the camera was able to capture every split-second aspect of the chameleon's tongue strike. Slowed down, the video allows you to see how every component of the process works in harmony: First, muscles in the lizard’s tongue contract like the string of a bow. Then, when that tension is released, the bony base of the tongue shoots forward, pushing the sticky, elastic part toward the chameleon’s prey.

According to Christopher Anderson, one of the scientists who conducted the high-speed camera research, larger chameleons can catapult their tongues forward at distances of one to two times their body length. For smaller chameleons, this distance can reach up to two and a half times their body length. “Small chameleons need to be able to eat more food for their body size than large chameleons,” he tells bioGraphic in the video, “and so by being able to project their tongues proportionately further than these large species, they basically are opening up additional feeding opportunities to themselves that they wouldn’t have if they had a shorter tongue.”

To see one of nature’s greatest hunting tools in action, check out the full video below.

[h/t The Kid Should See This]

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There May Be an Ancient Reason Why Your Dog Eats Poop
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Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]

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