Difficulty: Challenger (Level 2)
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? The secret lies in their tongues – a specialised tool that changes how they drink water and how it feels when they lick you.
How cats and dogs drink
When a cat drinks, it curls the tip of its tongue backwards 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 its mouth.
Surface tension is like an invisible, stretchy skin on a liquid’s surface that forms because tiny molecules in the liquid are always pulling on each other.
When a cat is drinking, surface tension allows the water to cling to the tongue, and the liquid is pulled upwards in a delicate 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 usually form. Water spills from the sides of the dog’s tongue before it closes its mouth, which can make a mess.
Why cat tongues feel rough
You may have noticed 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. Hollow and made of keratin, these projections act like a comb to tidy fur and remove knots.
This cleans the fur and helps cats to stay 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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