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Dolphins’ Snot May Be Essential to Their Communication

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We make lots of jokes about our bodily secretions, but they’re all there for a reason. Tears rinse our eyes, sweat helps keep us cool, and pee rids our bodies of waste. The types of fluids produced vary by species, as do their functions. Dolphin snot, for example, may be a necessary part of echolocation. Acoustic researchers are presenting their work on this concept at the annual meeting of the Acoustical Society of America this week in Salt Lake City.

Dolphin noise-making is incredibly sophisticated. Over the last half-century, we’ve learned that the clicks, whistles, and whines they produce help them track moving prey and communicate with one another. But just how they’re making these noises remains unknown.

"It's harder than you might think to make loud, high frequency sounds," Aaron Thode, a research scientist at the Scripps Institution of Oceanography in San Diego, said in a press statement. Want to try it for yourself? Here’s a sample. See if you can replicate it. We’ll wait. 

How’d you do? Not very well, we’re guessing. But don’t beat yourself up about it—you don’t have the anatomy for it. Dolphins' nasal passages are just under their blowholes. Inside those passages are lumps of flesh called bursae. Scientists believe that vibrating the bursae at high speed can make those shrieks and clicks possible. 

Still, they don’t know for sure. As you might imagine, it’s very hard to get a video of a dolphin vibrating its bursae. So Thode and his father, retired physicist Lester Thode, developed a computer model to recreate the buzzy bursae experience. 

Dolphin clicks have two parts: a thump, followed by a reverberation, like that of a bell. The Thodes built a model that would reproduce both the thump and the ring, then compared the simulated sounds with real dolphin noises recorded at the Hawaii Institute of Marine Biology and the Navy Marine Mammal Program. The simulator held up, successfully reproducing the timing, frequency, and overall sound of clicks from flesh-and-blood dolphins. 

Through manipulation of their virtual dolphin sound machines, the researchers found that the bursae produce clicks by pulling apart, then snapping together. But this stretch-and-snap action would be difficult to manage without, as they write in their presentation abstract, “some slight adhesion.” They believe the most likely source of that adhesion is mucus. 

More research will need to be done to confirm the snot theory. This study was done on computers, with one specific model. “Others could create a different model that also matches the data,” Lester Thode noted. There are no known plans to test the model with real dolphin boogers. 

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Animals
7 Fun Facts for Elephant Appreciation Day
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Happy Elephant Appreciation Day! Celebrate the occasion with some facts about everyone's favorite gentle giant. 

1. ELEPHANTS CAN RECOGNIZE OTHER ELEPHANT CARCASSES.

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The University of Sussex's Karen McComb told National Geographic that elephants "become excited and agitated if they come across a dead elephant," and, in particular, will investigate skulls and tusks. McComb teamed up with researchers at the Amboseli Elephant Research Project in Kenya to study the behavior, showing wild elephants a range of objects that included skulls. They found that the elephants examined skulls—and tusks in particular—of their own kind twice as long as other skulls, and examined tusks six times as long as they did pieces of wood. They were even able to recognize elephant skulls with the tusks removed, but didn't show preference for certain elephant skulls over others, which suggests they didn't know which skulls belonged to their own relatives. "Animals that are intensely social in life may be most likely to display an interest in their dead," McComb told National Geographic. "But what goes on in their minds while they are doing this is a total mystery."

2. THEY'RE SCARED OF BEES.

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Forget about mice scaring off elephants: When farmers need to keep elephants away from their crops, they should use bees. Researchers in Kenya discovered that even the recorded sound of buzzing bees was enough to make elephants retreat—and cause them to emit a low-frequency sound, inaudible to humans, that warns other elephants of the bees' presence.

"It's impossible to cover Africa in electric fences," Lucy King, author of the paper, told The Huffington Post. "The infrastructure doesn't exist in many places and it would restrict animals' movement." But something like a bee fence—hives strung on strong wires a certain distance apart that would move when elephants walked into them, disturbing the hives—"could be a better way to direct elephants away from farmers' crops," she said.

3. THEY MIGHT UNDERSTAND POINTING.

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Humans often use pointing as a way to nonverbally get a message across, though not many other animals grasp the concept. But according to a two-month study of 11 tame African elephants, these pachyderms might be able to: When presented with two identical buckets and pointed in the direction of the one containing food, elephants picked up on the cue fairly consistently: Elephants had a success rate of 67.5 percent (1-year-old humans have a success rate of 72.7 percent). But an earlier study of Asian elephants indicated that they don’t notice pointing gestures, which is a bit of a mystery.

4. ONE ELEPHANT CAN "TALK." 

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Koshik, an elephant in a South Korean zoo, developed the ability to imitate the sounds of five words he's heard from his trainer—annyeong (hello), anja (sit down), aniya (no), nuwo (lie down), and joa (good)—by sticking his trunk in his mouth. The scientists who first noticed Koshik’s ability speculate that he learned to “talk” because he was lonely.

5. THEY'RE DIGITIGRADES.

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It's Latin for "finger walking," and what it means is that elephants walk on their toes (there are five of them, as well a sixth false toe). According to the book Mammal Anatomy: An Illustrated Guidemost of the animals' weight "rests on a broad pad of elastic tissue behind the toes" which "acts as a shock absorber and prevents the skeleton from jolting too much when the animals walk. It also allows elephants to move surprisingly quietly despite their size."

6. AN ELEPHANT PREGNANCY LASTS ABOUT TWO YEARS.

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If you thought being pregnant for nine months was a long time, be glad you're not an elephant, which can be pregnant for up to 680 days, according to the BBC. All that time in the oven has a benefit, though: Elephant calves are born with highly-developed brains, capable of learning their herd's complex social structures and ready to put their trunks to use.

7. NINETY-SIX ELEPHANTS ARE KILLED IN AFRICA EVERY DAY.

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Unfortunately, elephant poaching remains a very big problem: An estimated 35,000 elephants are killed annually, their tusks sold illegally in the ivory market. Do the math, and that comes out to nearly 96 elephants every day. Find out what you can do to help elephants and stop poaching at 96Elephants.org.

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Bumblebees Mark Their Trails With Tiny Scented "Footprints"
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Yani Dubin via Flickr Creative Commons // CC BY-ND 2.0

Bees seem to have an endless number of tricks up their sleeve—and on their feet. Scientists have discovered that bumblebees leave itty-bitty scented “footprints” on every flower they visit, thereby informing other foragers that the bloom’s been recently tapped. The researchers published their findings in the journal Nature Scientific Reports.

Bees are the queens of complex communication. They exchange information with one another and their environments using a dazzling array of sensory input, including electrical impulses, sound, dance, and chemical signals.

Some of those signals flow out into the world through the bees’ delicate little feet. The bottom segment of a bee’s leg, called the tarsus, secretes a scented goo that helps the bee stick to the soft surfaces of flower petals. The chemical profile of each bee’s foot-glue is as unique as a fingerprint.

Previous studies have shown that bees glean important information from one another’s goo, skipping flowers that other bees have already visited. This raised an interesting question: If a bee can "read" another bee’s scent mark, can it also identify that bee?

To find out, researchers planted small clusters of fake flowers in the laboratory and topped some of them up them with sucrose nectar. They then gave bumblebees (Bombus terrestris) free rein to tromp around the blossoms, marking them up and taking in the marks of other bees that had come before.

The bees proved careful and canny readers. Not only did they use other bees’ scent marks to decide which flowers to probe, but they also considered the source of the scent when making that decision. An individual bee could easily differentiate between the smell of its own feet (trustworthy), those of its family members (very trustworthy), and those of strangers (not a reliable source of floral information).

Lead author Richard Pearce is a biologist at the University of Bristol. "Bumblebees are flexible learners and, as we have discovered, can detect whether or not it is they or a different bumblebee that has visited a flower recently. These impressive abilities allows them to be cleverer in their search for food, which will help them to be more successful," he said in a statement.

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