Watch a cat cross a room and you'll notice it moves on tiptoe. Cats, like dogs, walk on their toes, with the heel lifted high off the ground as part of what looks like the back of the leg. It is one reason they move so quietly. A cat's back paws often land almost exactly where its front paws have just been, leaving a neat single line of prints and barely a sound.
Those soft pads do a great deal of work. They cushion every landing, grip slippery surfaces and are packed with nerve endings that help an animal read the ground beneath it. They are also where dogs and cats do most of what little sweating they do. On a hot day, or on the vet's table, you may spot damp little paw prints appearing. That's no trick of the light.
Then there are the claws. Most cats keep theirs sheathed until needed, which keeps them sharp and silent. The cheetah is the famous exception, its claws only partly retractable, and blunter and straighter than those of other cats. Dogs' claws stay out all the time, ticking across kitchen floors and digging in for traction on a muddy bank.
Wild paws show real ingenuity. Snow leopards and lynx have broad, heavily furred paws that work like snowshoes. A polar bear's soles, as wide as dinner plates, are covered in small soft bumps that grip the ice, with tufts of fur between the pads for warmth. River otters have webbed paws for swimming. Red pandas have an extended wrist bone that acts like a false thumb, perfect for holding bamboo. Bears, unusually, walk flat-footed, heel and all, much as we do.
And the smell. Many dog owners have noticed that their dog's paws carry a faint, oddly familiar scent, often compared to corn chips. Vets put it down to bacteria that live naturally on the skin between the toes. Usually harmless, and a strangely comforting smell to anyone who has ever buried their face in a sleepy dog.
The next time a paw lands on your knee, it may deserve a closer look. There is a lot going on down there.
Sources: Digitigrade · AKC, do dogs sweat? · PetMD, how do cats sweat? · Cheetah · Polar Bears International · Smithsonian, red panda facts · Plantigrade · AKC, why dog feet smell like corn chips