Why do our fingers get wrinkly in water, but the rest of our skin doesn’t?
In: Biology
It’s an active response not a “skin absorbing water” type of thing. We know this because people with nerve damage in their hands or arms don’t have this response and their hands doesn’t get wrinkly in water! If the “I’m in water” signal can’t reach from the hands to the brain, the wrinkles don’t happen, so we know it’s an active process not just passive absorption, because then it would happen whether you can feel your hands or not.
As for why it happens, leading theory is for better grip on wet objects and underwater surfaces. That makes sense with how it happens on your feet in water eventually too. Only hands and feet get pruny, and that’s everything you grab and grip with.
Also, the mechanism seems to be small blood vessels in the hands and feet constricting. So your hands and feet slightly shrink, leaving the skin fitting like a glove that’s too big – hence the wrinkles. Once you dry off, the blood vessels open up again, your hand and feet re-inflate, and the skin fit more snugly again.
Source+ more info:
[Why Water Turns Fingers and Toes Into Prunes (clevelandclinic.org)](https://health.clevelandclinic.org/why-water-makes-your-skin-look-like-a-prune-and-not-a-plum)
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