Why your fingers wrinkle in water

When fingertips stay underwater, the autonomic nervous system constricts small blood vessels in the fingertip pulp. The tissue underneath loses volume, and the skin folds into ridges and valleys. 1

The folds may help wet fingers handle slippery objects. In a 2013 experiment, 20 people moved submerged objects in 12% less time with wrinkled fingers than with unwrinkled fingers; dry objects showed no such difference. The experiment supported a wet-grip benefit, while the exact role of the grooves—channeling water, changing friction, or both—remains open. 2 A later study found that wrinkled fingers also used less grip force on wet objects, bringing performance close to dry-finger handling. 3