Science vlogger Kyle Hill (previously), amusingly debunks the myth that cats scratch at the living room couch with their claws in order to sharpen them. Instead, Hill explains the lesser-known biological reason as to why cats are driven to stretch out their claws on softer surfaces.
Cats shed their claws. When cats scratch, they are not continuously sharpening the same structure…cat’s claws are so sharp because they don’t sharpen them. When they make this… pulling grabbing motion, what they’re actually doing is encouraging the keratin furthest away from the blood supply of their little toe beans to shed, always revealing a top of the line sharp as possible mouse shredding implement.
via The Awesomer