When people compare dogs and cats, they are usually thinking about the differences between keeping these two animals as pets. But have you ever wondered about their different drinking styles?
Their tongues change how they drink water and how it feels when they lick you. Let’s sniff out what you should know about the tongues of dogs and cats.
How cats and dogs drink
Humans bring a cup up to their lips with their hands. Or if they use straws, their mouths form a tight seal and suck to bring liquid upwards.
Cats and dogs have mouths that open wide because they are meant for hunting. But they cannot form a tight seal to create the suction needed to sip. As a result, they use a lapping motion to bring liquid into their mouths.
But why do dogs create big splashes when they lap water, while cats neatly and gracefully drink?
When a cat drinks, it curls the tip of its tongue back and touches only the surface of the water. As the tongue quickly pulls back in, it relies on surface tension to pull the water into the mouth. Surface tension is like a stretchy skin on a liquid’s surface. This forms because tiny molecules that make up a liquid are always pulling on each other.
Surface tension allows the water to cling to the cat’s tongue, and the liquid is pulled up in a thin column. The cat then snaps its jaws shut to catch the water before gravity breaks the column apart.
Dogs also use surface tension, but they curl their tongues backwards into a large, ladle-like shape that punches the water. This brings up a much larger column than what cats typically form. Dogs can take bigger gulps, but they also create a messy splash. Water spills from the sides of the dog’s tongue before it can close its mouth.
Why cat tongues feel rough
Beyond their drinking styles, you may have noticed another striking difference between the tongues of dogs and cats. A cat’s lick feels like sandpaper, while a dog’s feels soft and wet. This comes from the structure of the tiny projections, called papillae, that cover their tongues.
Cats have rigid and sharp papillae that face backwards. These projections are hollow and made of keratin. They act like a comb to tidy fur and remove knots. They keep cats cool as the saliva evaporates on their skin (see graphic).
Dogs also have these projections, but theirs are much softer, giving their tongues a smooth feel. That is why they do not lick their fur as much as cats do.
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