Why are dogs such messy drinkers? It’s because they don’t suck, according to a new study.

Anyone who owns a dog knows just how much of a mess it can make when drinking water, slapping its tongue against the water, versus cats, who make a much quieter job of it.

The reason for this had been a mystery for scientists, until now, according to the Daily Mail.

Using high-speed cameras, researchers at Virginia Tech and Purdue University found that dogs slap the water with their tongues to create water columns that feed into their mouths. The researchers found this by modelling the fluid dynamics that came into play when dogs of different sizes drank water.

Both dogs and cats are considered predatory quadrupeds, which means they lack “complete cheeks” due to their large jaws, which are more focused on being able to open wide to take down an animal. This makes it impossible for them to suck water into their mouths, unlike humans, who do have “complete” cheeks. These cheeks allow us to create what is called “negative pressure” to facilitate the flow of water.

Meanwhile, cats also lack suction, but they are able to use a two-part “water entry and exit” process” by using the tip of their tongues to touch the surface of the water and quickly withdraw it to generate a column of water under their tongues, according to the research.

Researchers used cameras under the surface of the water to map the surface area of the dogs’ tongues when they hit the water, and found that heavier dogs drink water with a larger area of the tongue.

The research team went so far as to create models of the tongues of different sizes of dogs, allowing them to mimic water column formation created by dogs, then measuring the amount of water withdrawn. The dogs apparently use gravity to get the water into their mouths.

Cats tend to be more “elegant” drinkers in that they don’t dip their tongues into the liquid like dogs do, making their lapping technique more subtle.

The team will present their findings at the American Physical Society’s Division of Fluid Dynamics meeting in San Francisco today.