Ha!—the dogs are
just prepping for big slobbery kisses don’t you know!
From: Research Administration List [mailto:xxxxxx@hrinet.org]
On Behalf Of Aubert, Brenda
Sent: Friday, November 12, 2010
1:11 PM
To: xxxxxx@hrinet.org
Subject: Re: [RESADM-L] It's
Friday, so you deserve a good research story: For Cats, a Big Gulp With a Touch
of the Tongue
Awesome
story! Yet another discovery to stroke the cat’s superiority complex over
their canine friends!
From: Research Administration List [mailto:xxxxxx@hrinet.org]
On Behalf Of Carolyn
Elliott-Farino
Sent: Friday, November 12, 2010
12:47 PM
To: xxxxxx@hrinet.org
Subject: [RESADM-L] It's Friday,
so you deserve a good research story: For Cats, a Big Gulp With a Touch of the
Tongue
Here’s a good
research story for a Friday.
For Cats, a Big Gulp With a Touch of the
Tongue
Published: November 11, 2010
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.
Pedro Reis
Cutta
Cutta, who inspired the study, belongs to a researcher at M.I.T.
Cats lap water so
fast that the human eye cannot follow what is happening, which is why the trick
had apparently escaped attention until now. With the use of 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 his mouth to create
suction, as people can. But the various species that cannot do so — and that
includes most adult carnivores — must resort to some other mechanism.
Dog owners are
familiar with the unseemly lapping noises that ensue when their thirsty pet
meets a bowl of water. The dog is thrusting its tongue into the water, forming
a crude cup with it and hauling the liquid back into the muzzle.
Writing in the
Thursday 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 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 behind it.
Just at the moment
that gravity finally overcomes the 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 anything 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 a cat’s
tongue, using a glass disk at the end of a piston to serve as the tip. After
calculating 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 that 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, the nonprofit group that operates
the Franklin Park Zoo in Boston and the Stone
Zoo in Stoneham, Mass., who let them videotape his big cats.
Lions, leopards, jaguars and ocelots turned out to lap at the speeds predicted
by the engineers.
The animal 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, like 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 Dr. Reis, an expert in fluid mechanics,
and the study was under way.
At first, Dr.
Stocker and his colleagues assumed that the raspy hairs on a cat’s tongue, so
useful for grooming, must also be involved in drawing water into its mouth. But
the tip of the tongue, which is smooth, turned out to be all that was needed.
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 simply borrowed it from a
neighboring lab.
A version of this article appeared in print on
November 12, 2010, on page A19 of the New
York edition.
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