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New Scientist TV:

High-speed video shows how the cat gets the cream

Catherine de Lange, reporter

Drinking from a receptacle is no mean feat. Humans get around this by tilting a glass or sucking up their drink through a straw. But for our feline friends, it's a tougher challenge.

Now Pedro Reis and his team from the Massachusetts Institute of Technology have filmed cats as they lap up milk to see precisely how they do it (see video above). The video has revealed that it's a battle between inertia - how much a substance resists other forces - and gravity.

"Almost everyone has observed a domestic cat lap milk or water. Yet, casual observation hardly captures the elegance and complexity of this act, as the tongue's action is too fast to be resolved by the naked eye," writes Reis.

The high speed footage allowed the team to look at the tongue's action in greater detail. They discovered that cats dip their tongue in, bending it into an inverted "J" shape so the top touches the liquid but never breaks the surface. A column of liquid is created when the tongue is retracted, and the cat quickly snaps its mouth shut around the liquid before it falls back down.

The team also found that the famously rough texture of the cat's tongue isn't used for lapping. Video footage revealed that only the tip of the tongue - which is smooth and without any hair-like structures - is used to drink.

To better understand the fluid dynamics at work, Reis and his team also created a mechanical model to mimic the lapping motion. They found that liquid ended up in the cat's mouth thanks to a delicate balance between inertia, acting on the liquid as it sticks to the tongue and travels towards the cat's mouth, and gravity, pulling the liquid back towards the bowl.

"The amount of liquid available to capture each time the cat closes its mouth depends on the speed and size of the tongue," says Jeffrey Aristoff, who was part of the team. Bigger cats with larger tongues should then lap more slowly.

Along with elephant trunks and octopus arms, understanding soft structures like a cat's tongue can lead to better design of soft robots and biomechanical models, say the authors.

The research is published in the journal Science.

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1 Comment

A interesting video on a interesting subject showing the differnce between humans and cats drink.liquids.

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