Cats cannot close their mouths and create suction. With help from high-speed
video taken of felines lapping liquid, researchers at the Massachusetts
Institute of Technology (MIT) and Princeton University found that household
cats and larger felines like tigers balance gravity and inertia as they imbibe
liquids. They observed when cats insert their tongue into a bowl of liquid, the
top surface of the tongue touches the liquid first, then the tip curves like a
letter J to form a sort of ladle. This was first observed by an MIT engineer,
who filmed a cat lapping liquid in 1940.
However by studying the images researchers have now determined that there is
no ladling effect, but instead the cat's tongue darts in and out so quickly
that the action forms a column of liquid.
"Cats, unlike dogs, aren't dipping their tongues into the liquid like
ladles after all," Instead, the smooth tip of cat's tongue "barely
brushes the surface of the liquid before the cat rapidly draws its tongue back
up. "As it does so, a column of milk forms between the moving tongue and
the liquid's surface. The cat then closes its mouth, pinching off the top of
the column for a nice drink, while keeping its chin dry."
The liquid column "is created by a delicate balance between gravity,
which pulls the liquid back to the bowl, and inertia, which in physics, refers
to the tendency of the liquid or any matter, to continue moving in a direction
unless another force interferes."
The cat "instinctively knows just how quickly to lap in order to
balance these two forces, and just when to close its mouth. If it waits another
fraction of a second, the force of gravity will overtake inertia, causing the
column to break, the liquid to fall back into the bowl, and the cat's tongue to
come up empty."
Cats average about four laps per second, with each lap bringing in about 0.1
milliliters of liquid, the researchers said, adding that larger felines lap at
a slower pace.
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