When do cats extend their claws?

I have owned cats for close to 20 years now. I never declawed any of them. A cat sharpens its claws for the same reason a cat knows to chase mice. Even when not taught or guided by another cat. It is done by instinct. She figures her claws should be sharp for when she needs to hunt for food.

Another thing a cat does by instinct is to scratch the ground next to his or her bowl of food. The reason why they do this is because they do not like the food or are not hungry anymore; in an attempt to bury the food. In which case a cat in the wild can go back when his food has run out to retrieve it and not starve. Even when they do not like it, they will be able to survive.