Why does the skin of the fingers and toes become wrinkled after prolonged immersion in water?

Answer 1

Because the skin has adapted to function in an aerobic medium ideally.... You have dead layers of skin cells over your living flesh as a protective layer against water getting in.... but thats not to say that the water cannot get into the surface cells... dilute them... expand them ... and... well... if all the cells are expanded but held in a limited area then they're going to wrinkle....

Answer 2

In a word, keratin, comprised of the cytoplasm of dead skin cells. Under the microscope, the layer is actually much thicker than the epidermal layer itself, otherwise our skin surfaces would look much like the inside of the mouth. It absorbs water and increases in volume when it has water in it. Skin expands, wrinkles. Water evaporates, skin goes back to its normal contour. Simple as that.