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Sip, don’t slurp!

If Emily Post wrote an etiquette guide for animals, you’d probably find a photo of Frisky Feline beside tea party etiquette. And a dire warning to Max the Mutt not to make those repulsive slurping sounds while drinking!

Cat lovers everywhere know their feline friends’ gravity-defying grace, but have you ever noticed that those traits even extend to how they lap their beverages?

Tea Party Etiquette

Unlike humans, who seal their cheeks to suck in liquids, dogs and cats rely on lapping. Dogs sloppily slurp water from the bowl often getting their chins and snouts wet. Frisky Feline’s lapping mechanism is far more subtle and elegant, leaving his whiskers and chin dry.

Four MIT scientists painstakingly filmed, analyzed and determined how a cat can drink water while keeping its chin and whiskers pleasantly dry. The unusual experiments – which took 3-1/2 years – involved 10 domestic cats, one robotic cat, four zoo animals and six YouTube videos of large cats in zoos and on safaris.

The first thing the researchers noticed is that cats and dogs drink very differently. Both animals extend their tongues and curl them back toward their chins as they approach water. But dogs use their bent tongues as a ladle, spooning water into their mouths. Cats touched only the top surface of their tongue to the water.

 How a cat personifies daintiness
 
Cats extend their tongues straight down with the tip curled backward like a capital "J" to form a ladle.
  • The smooth tip of the tongue barely brushes the surface of the liquid before the cat rapidly draws its tongue back up at a rate of almost four laps per second, with each lap bringing in about 0.1 milliliters of liquid. At four laps per second, that’s nearly 24 ml (5 teaspoons) a minute.
  •  A liquid column is created by the physics involved — that is, the balance between upward movement of the water set off by the cat’s tongue (the inertia) and the gravity pulling the water down.
  • The cat instinctively knows just how quickly to lap in order to balance these two forces, and just when to close its mouth, pinching off the top of the column for a nice drink, while keeping its chin dry.
To verify the forces at work, the researchers built a robotic tongue. A simple glass disk – the tongue moved at different rates so researchers could calculate the volume of water ingested with each lap.
 
The model allowed the researchers to predict that all cats – large and small – share the same basic drinking pattern, although the larger ones slowed down their lapping to strike a balance between the inertia and gravity of the water picked up by their tongues. Videos indicate that lions and tigers lap less than 2 times per second, about half the rate of domestic cats.