(Inside Science) -- The giraffe"s neck — advantageous for reaching the loftiest acacia leaves or because that slugging would-be rivals — has its drawbacks. When the creature stoops to take a drink, because that example, it should spread its former legs and also lower its head to the water"s surface. How a giraffe, the tallest pet on earth, then propels that water increase its lengthy neck to reach its stomach has been a mystery. Now, brand-new research argues the mystery may lie with a simple machine known as a plunger pump.

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The spark that kindled this insight struck Philippe Binder last year in Namibia"s Etosha national Park. He was sitting in a tour bus, watching a giraffe drink from a surrounding watering hole.

"I thought, "Wow, this is weird. Obtaining water up that long neck can"t be easy,"" the said.

Binder is a physicist at the university of Hawaii at Hilo, where he studies nonlinear dynamics and chaos theory and seldom to meet giraffes. But while ~ above sabbatical at the university of Cape town in southern Africa, Binder couldn"t gain the photo of the thirsty giraffe out of his head.

"Physicists regularly have a childlike curiosity to know why things perform what castle do," that said. "I just wanted to understand how giraffes drink. It to be sheer, pure fun."

He enlisted the help of Dale Taylor, a physicist in ~ the college of Cape Town, and also the two collection about accumulating giraffe minutiae — neck length, stomach capacity, size of common drinking illustration — and also searching for possible mechanisms behind the behavior.

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At first, the researchers thought that the animal might be making use of its neck prefer a giant, 8-foot-long drinking straw — lowering the air press in its esophagus and stomach and enabling atmospheric press to press the liquid up that is esophagus. However they scrapped that idea after ~ calculating the giraffes are likely unable to generate the pressure distinction needed to lift the water from their lips to your shoulders.

Then two hints pointed them towards plunger pumps: a veterinary and also medical textbook native 1890 that stated ruminants choose cows and also sheep use their tongue favor a plunger to pump water into their esophagus and a YouTube video with a close-up of a giraffe in ~ the Phoenix Zoo in Arizona drink in a suspiciously pump-like way.


Typically, a plunger pump supplies one hit to attract water or various other fluids right into a cavity with one valve and then one more stroke to push the liquid the end again through a second valve. Sport of the pump are usual in wastewater treatment and also the oil and also gas industry.

But where execute giraffes store their plunger pumps?

In the model proposed by the researchers, the giraffe"s lips type one valve of the "pump" if the animal"s epiglottis, situated at the earlier of the mouth, is the other. Come start, the giraffe sink its puckered lips right into the water and then pulls earlier its jaw, allowing water to rush into the mouth while keeping the epiglottis "valve" closed. Next, the giraffe clenches that is lips, relaxes the epiglottis, and also pumps that jaw so the the caught water is pushed right into the esophagus.


The bicycle repeats, moving more and more water right into the esophagus. At some point, the giraffe lifts its neck, and the water sluices into its stomach, thanks to gravity and the wave-like muscular contractions known as peristalsis.

The researchers estimate that the giraffe pumps water in at a rate of around 6.7 mph — fast sufficient to get over the press from the water that"s already stored in the esophagus and also preventing the from rushing earlier out.

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Based on the dimensions of a giraffe esophagus, the researchers estimated that a full one can hold around 1.3 gallons. Extr calculations revealed that each pump more than likely sends about 10 ounces the water right into the throat and that a long drinking episode of around 25 seconds could involve as much as 17 pump cycles. Thus, a parched giraffe would nearly fill its esophagus to the brim, follow to Binder and also Taylor"s research, released in December in the journal The Physics Teacher.

"It"s a really good observation," said Sunghwan Jung, a biophysicist in ~ Virginia Tech, who wasn"t involved in the research. "But to recognize for certain whether giraffes drink this way, they"ll have to use X-rays to watch inside the mouth."

In the past, Jung and his colleagues have actually employed high-speed photography and engineered models come reveal how other pets such together cats and dogs drink. Those animals use a different strategy 보다 giraffes or various other herbivores favor cows and horses, the said. Quite than putting their lips on the water surface and opening their mouth, cats and also dogs "push their tongue in and out and create a water obelisk in the air, which they bite under on."

X-rays would be illuminating and perhaps expose what role, if any, the giraffe"s tongue dram in the process, claimed Binder. However he"s cynical many world would be ready or able come secure the leggy animal"s cooperation. "Besides, what X-ray machine would be big enough?"

Instead, he"s considering looking into using together a method on smaller sized targets favor goats to view if lock drink in connected ways. In the meantime, stated Binder, "I understand I"ll never look in ~ a giraffe the same."

"I"ve constantly wondered exactly how giraffes obtain water every the way up the big, long pipe," stated David O"Connor, a conservation ecologist in ~ the san Diego Zoo who has studied the stately creatures in the wild. But, that said, it"s simply one the the numerous mysteries the envelop the animals. "We don"t also know for specific why the lengthy neck evolved. It absolutely wasn"t because that drinking."