Cats use inertia to drink while dogs scoop up the liquid

Cats and dogs drink in very different ways. I don’t want to sound biased but cats employ a far more sophisticated technique based upon fancy physics. Whereas dogs use their tongues to ladle the liquid into their mouths by scooping it up, cats use the physics of inertia to overcome the pull of gravity to “kick” the liquid into their mouths.

It may surprise people to know that cats do not ladle water into their mouths in a tongue which is U-shaped and which scoops up the water (although it looks like it). This is a misconception. The tongue is in an inverted “J” shape when it contacts the water as shown in the sequence of pictures below taken as screenshots from the video at the base of the page.

Cat's tongue at the beginning of the lapping sequence as it makes contact with the liquid
Cat’s tongue at the beginning of the lapping sequence as it makes contact with the liquid. Screenshot.
Cat's tongue as it moves backwards moving the milk which then moves through the physics of inertia overcoming gravity
Cat’s tongue as it moves backwards moving the milk which then moves up towards the mouth through the physics of inertia overcoming gravity. Screenshot.
The column of milk is lifted into the air by the tongue's backward motion. The milk is moved by the tongue and it continues to move as it is pushed into the air and thence to the mouth. It is not laddled up.
The column of milk is lifted into the air by the tongue’s backward motion. The milk is moved by the tongue and it continues to move as it is pushed into the air and thence to the mouth. It is not laddled up. It is kicked up into a column of milk which overcomes gravity. Screenshot.
The milk is inside the mouth as the column of milk falls back to the bowl
The milk is inside the mouth as the column of milk falls back to the bowl. Screenshot.

The tongue then moves the liquid backwards (surprisingly) and once it is moving its inertia keeps it moving whereby it forms a column which is stretched by the downward pull of gravity. The cat is able to ingest a part of this column of water (or milk in this example) before the remainder falls back into the bowl. It is an incredibly complicated piece of science and the domestic cat carries it out entirely instinctively.

Domestic cats complete four laps per second. This is almost 5 teaspoons or 25 millilitres of liquid a minute. Each lapping of liquid results in 0.1 millilitres of liquid going into their mouths.

Researchers found that larger cats need to lap liquids at a slower rate in order to strike the correct and critical balance between inertia and gravity to allow the process to work. They found that lions and tigers lap at less than two times per second which is about half the rate of domestic cats.

In conclusion, therefore, and to restate the point because I think it needs restating, cats do not ladle liquid up into their mouths with their tongues in a U-shaped, but simply move the liquid with the tip of their tongues, projecting it up into the air and it continues to move through the physical properties of inertia when it forms a column which overcomes the downward pull of gravity. The cat ingests a part of this column of water before the remainder falls back.

Inertia

From Wikipedia: Inertia is the resistance of any physical object to any change in its velocity. This includes changes to the object’s speed, or direction of motion. An aspect of this property is the tendency of objects to keep moving in a straight line at a constant speed, when no forces act upon them.

From Roman Stocker, a professor of civil and environmental engineering at the Massachusetts Institute of Technology: think “objects in motion tend to stay in motion”.

The film maker says: Meet Rufus. Amazing Norwegian Forest Cat sequence. Super Slow Motion. Filmed at 2000FPS on the Phantom Flex4K.

Leave a Comment

follow it link and logo