Why Do Fingers wrinkle in Water?
There are several theories put forward by the biologists to explain the wrinkles in finger skin when it stays in water for few minutes. Most of the scientists think that the thick layer of skin which is made up of dead keratin cells is playing the role of the wrinkle formation. The outer layer of the skin is called as epidermis and the inner layer is called as dermis. Epidermis is connected with the dermis at certain places and the connection is not continuous.
It is found that our skin usually is surrounded by an oily protein substance called sebum. When we keep our skin for some time in water, the sebum will get moved away and create a space for the water to contact with the keratin cells. The dead keratin cells absorb water and this makes the skin surface bulged. There is no clear space between the epidermis and dermis and the skin is attached to the living tissue of the dermis. This makes the bulged layer of skin to appear as if it is been dragged back. As the swollen skin is held tightly by the dermis layer, wrinkles appear on the outer skin. The exact description for the wrinkles is that there will be a trough where the epidermis is attached to the dermis and a ridge or bulge where it is not linked with the dermis.
Normally, the finger skin does not wrinkle when water just falls on it because the oily sebum will prevent the water from being absorbed by the keratin cells. Only when the fingers are retained in water for sometime and the oil is washed away will the absorption of water by the keratin cells be facilitated.
As soon as the fingers are taken out from water the absorbed water by the keratin cells gets evaporated and the skin regains its normal state.