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We now know how cats drink!!!
Imagine the implications! Worried that your ship's hull might have a few leaks? Fret not, just bring a few cats on board. Does your shower have weak water pressure? Just bring the cat in the tub. Floods will be a thing of the past. Mouth to mouth resuscitation now needs only to worry about hairballs. It's amazing!
November 11, 2010
For Cats, a Big Gulp With a Tiny Touch of the Tongue
By NICHOLAS WADE
It has taken four highly qualified engineers and a bunch of integral equations to figure it out, but we now know how cats drink. The answer is: very elegantly, and not at all the way you might suppose.
Cats lap water so fast that the human eye cannot follow what is happening, which is why their imbibing trick had apparently escaped attention until now. With high-speed photography, the neatness of the feline solution has been captured.
The act of drinking may seem like no big deal for anyone who can fully close the mouth to create suction, as people can. But species that cannot, which includes most carnivores, must resort to some other mechanism.
Dog owners are familiar with the disgusting lapping noises that ensue when a thirsty animal meets a pail of water. The dog is thrusting its tongue into the water, forming a crude cup with its tongue and hauling the liquid back into its muzzle.
Cats, both big and little, are so much classier, according to new research by Pedro M. Reis and Roman Stocker of the Massachusetts Institute of Technology, joined by Sunghwan Jung of the Virginia Polytechnic Institute and Jeffrey M. Aristoff of Princeton.
Writing in Thursday’s issue of Science, the four engineers report that the cat’s lapping method depends on its instinctive ability to calculate the balance between opposing gravitational and inertial forces.
What happens is that the cat darts out its tongue, curving the upper side downward so that the tip lightly touches the surface of the water.
The tongue is then pulled upward at high speed, drawing a column of water up behind it.
Just at the moment that gravity finally overcomes the upward rush of the water and starts to pull the column down — snap! The cat’s jaws have closed over the jet of water and swallowed it.
The cat laps four times a second — too fast for the human eye to see but a blur — and its tongue moves at a speed of one meter per second.
Being engineers, the cat-lapping team next tested its findings with a machine that mimicked the action of the cat’s tongue, using a glass disk at the end of a piston to serve as the tip of the cat’s tongue. After calculation of things like the Froude number and the aspect ratio, they were able to figure out how fast a cat should lap to get the greatest amount of water into its mouth. The cats, it turns out, were way ahead of them — they lap at just this speed.
To the scientific mind, the next obvious question is whether bigger cats should lap at different speeds. The engineers worked out a formula: the lapping frequency should be the weight of the cat species, raised to the power of minus one sixth, and multiplied by 4.6. They then made friends with a curator at Zoo New England who let them videotape his big cats. Lions, leopards, jaguars and ocelots turned out to lap at the speeds predicted by the formula.
The feline who inspired this exercise of the engineer’s art is a black cat named Cutta Cutta who belongs to Dr. Stocker and his family. Cutta Cutta’s name comes from the word for “many stars” in Jawoyn, a language of the Australian Aborigines.
Dr. Stocker’s day job at M.I.T. is applying physics to biological problems, such as how plankton move in the ocean. “Three and a half years ago I was watching Cutta Cutta lap over breakfast,” Dr. Stocker said. Naturally he wondered what hydrodynamic problems the cat might be solving. He consulted with his colleague Dr. Reis, an expert in fluid mechanics, and the study was underway.
At first they assumed that the raspy hairs on a cat’s tongue, so useful for grooming, must also be involved in drawing water into the mouth. But the tip of the tongue, which is smooth, turned out to be all that was needed to generate the column of water.
Remarkably for a scientific experiment, the project required no financing. The robot that mimicked the cat’s tongue was built for an experiment on the International Space Station and the engineers just borrowed it from a neighboring lab.
For Cats, a Big Gulp With a Tiny Touch of the Tongue
By NICHOLAS WADE
It has taken four highly qualified engineers and a bunch of integral equations to figure it out, but we now know how cats drink. The answer is: very elegantly, and not at all the way you might suppose.
Cats lap water so fast that the human eye cannot follow what is happening, which is why their imbibing trick had apparently escaped attention until now. With high-speed photography, the neatness of the feline solution has been captured.
The act of drinking may seem like no big deal for anyone who can fully close the mouth to create suction, as people can. But species that cannot, which includes most carnivores, must resort to some other mechanism.
Dog owners are familiar with the disgusting lapping noises that ensue when a thirsty animal meets a pail of water. The dog is thrusting its tongue into the water, forming a crude cup with its tongue and hauling the liquid back into its muzzle.
Cats, both big and little, are so much classier, according to new research by Pedro M. Reis and Roman Stocker of the Massachusetts Institute of Technology, joined by Sunghwan Jung of the Virginia Polytechnic Institute and Jeffrey M. Aristoff of Princeton.
Writing in Thursday’s issue of Science, the four engineers report that the cat’s lapping method depends on its instinctive ability to calculate the balance between opposing gravitational and inertial forces.
What happens is that the cat darts out its tongue, curving the upper side downward so that the tip lightly touches the surface of the water.
The tongue is then pulled upward at high speed, drawing a column of water up behind it.
Just at the moment that gravity finally overcomes the upward rush of the water and starts to pull the column down — snap! The cat’s jaws have closed over the jet of water and swallowed it.
The cat laps four times a second — too fast for the human eye to see but a blur — and its tongue moves at a speed of one meter per second.
Being engineers, the cat-lapping team next tested its findings with a machine that mimicked the action of the cat’s tongue, using a glass disk at the end of a piston to serve as the tip of the cat’s tongue. After calculation of things like the Froude number and the aspect ratio, they were able to figure out how fast a cat should lap to get the greatest amount of water into its mouth. The cats, it turns out, were way ahead of them — they lap at just this speed.
To the scientific mind, the next obvious question is whether bigger cats should lap at different speeds. The engineers worked out a formula: the lapping frequency should be the weight of the cat species, raised to the power of minus one sixth, and multiplied by 4.6. They then made friends with a curator at Zoo New England who let them videotape his big cats. Lions, leopards, jaguars and ocelots turned out to lap at the speeds predicted by the formula.
The feline who inspired this exercise of the engineer’s art is a black cat named Cutta Cutta who belongs to Dr. Stocker and his family. Cutta Cutta’s name comes from the word for “many stars” in Jawoyn, a language of the Australian Aborigines.
Dr. Stocker’s day job at M.I.T. is applying physics to biological problems, such as how plankton move in the ocean. “Three and a half years ago I was watching Cutta Cutta lap over breakfast,” Dr. Stocker said. Naturally he wondered what hydrodynamic problems the cat might be solving. He consulted with his colleague Dr. Reis, an expert in fluid mechanics, and the study was underway.
At first they assumed that the raspy hairs on a cat’s tongue, so useful for grooming, must also be involved in drawing water into the mouth. But the tip of the tongue, which is smooth, turned out to be all that was needed to generate the column of water.
Remarkably for a scientific experiment, the project required no financing. The robot that mimicked the cat’s tongue was built for an experiment on the International Space Station and the engineers just borrowed it from a neighboring lab.
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