Why Fingers Wrinkle in Water

Daven Hiskey 19
Wrinkled FingersToday I found out why fingers wrinkle in water. For the quick answer, water washes away an oily substance that protects your skin.  When that happens, a certain type of dead cell on your skin will absorb the water causing the cells to swell up, but the layer underneath does not.  So the swelling, combined with the places the skin is connected underneath to the non-swelled layer, causes your finger tips to look all wrinkly.

So that’s the quick, generic answer.  More technically, there is a  waxy/oily substance your skin secretes from the sebaceous glands called “sebum”.  In these glands, sebum is produced within special cells and is then secreted when these cells burst.  This substance, among other benefits, has the dual effect of helping your skin and hair stay hydrated underneath, so it doesn’t get dry and cracked, while also helping to protect your skin from excess moisture from the outside.  You will have probably noticed sebum at some point in your hair if you go a couple days without washing it.  Your hair will start to feel very oily when you run your hands through it.  When you are in water for extended periods, this sebum gets washed away from your skin and hair, removing this protective layer.

Now you might be wondering why only your finger tips and toes get wrinkly and not the rest of your body (or at least not nearly as fast).  The reason why is not 100% understood, but we do have a pretty good idea of what is going on here.  The skin’s outermost layer, the epidermis, contains a protein called keratin.  This protein helps strengthen your skin.  Dead keratin cells also make up the epidermis’ surface layer, called the stratum corneum (Latin for ‘horny layer’, funny enough).  So once all the protective sebum is washed away, these dead keratin cells absorb the water like a sponge and swell.  This is why your skin is much easier to cut or break when it is waterlogged.  The strong outer layer of dead keratin cells loses some of its toughness when waterlogged.   The reason then that your toes and fingers get more wrinkly is that they contain a thicker layer of both living and dead keratin cells than the rest of your body.  This causes them to swell more noticeably then the rest of your skin as the dead keratin cells absorb water.

The wrinkle effect occurs, rather than just general swelling, because the inner layer of living keratin cells stays more or less the same as it was before you were in the water, while the outer layer swells;  the connections between these two layers stay closely bonded while the places not connected are free to swell, hence, the pruney fingers and toes.

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19 Comments »

  1. Mrs. P January 22, 2010 at 8:16 am - Reply

    In addition, if you are a diabetic and your fingertips get “pruny” but you are NOT taking a bath, it is a signal that you are getting dehydrated and need to have a nice glass of water.

  2. Coy Mcdonough February 1, 2010 at 5:37 am - Reply

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  3. Mrs.R July 28, 2011 at 7:49 pm - Reply

    always wanted to know why we wrinkle up

  4. rich August 14, 2011 at 6:42 pm - Reply

    Did anyone notice that the kid in the picture does not have thumbs?

  5. Tamber August 18, 2011 at 5:09 pm - Reply

    It is also thought that the wrinkling helps your fingers to grip in the same way as tyre treads grip in the wet.

  6. Jane September 18, 2011 at 8:03 pm - Reply

    I’m sorry but why then “cutting nerves in a finger prevents the wrinkling”?

  7. Mrtn February 2, 2012 at 8:02 pm - Reply

    This article is wrong. This WAS why we thought our hands and feet get wrinkly in water, but the skin on our hands etc actually don’t absorb much water, at least not to such a notable degree that you’d see such swelling (and why also in such strange patterns, and not just overall?), and also – the skin on our head, face and scalp are much more sebum and keratin-stuffed than our hands and feet could ever be, yet you never see the same reaction there. Obviously, there is something else at work here.

    The real cause is actually very simple, and also very interesting: When our hands and feet have been in water for a long time, a nerve reaction from the skin to the brain, likely caused by chemical processes in the skin, triggers a response where the skin tightens up to make it wrinkly. This is why people who have their nerves cut over don’t get wrinkly skin in water (like Jane pointed out), and this also explains why no other part of the body reacts in the same way, since only some nerve reactions are triggered by this. The practical function is that this leads water away from our hands and feet, enabling us to have greater grip on wet surfaces (much like tires on a car). The biological theory is, if you can imagine way back in our evolution, that this was a way for us to have greater grip on slippery/wet surfaces when we were still living in fairly aquatic surroundings, and it’s stuck with us ever since, even though we don’t necessarily spend that much time in water any longer.

    So there, that’s why the skin wrinkles up in water. Makes sense and even sounds a lot cooler. Kinda makes me feel like a lizard man :P Cheers!

  8. rassa February 9, 2012 at 11:37 am - Reply

    @rich look where the palms meet. you will see thumbs

  9. Rachael March 21, 2012 at 12:43 am - Reply

    So this is interesting…I am a swimmer. I used to swim up to 4 hours a day, 6 days a week when I was in high school. I don’t think I really ever got prun-y then. I only swim about 3 times a week now and not for nearly as long…like maybe an hour. I prune really bad now…so do your nerves just adjust to how much you are in the water and decide not to send the signals as much if it seems to be part of your normal habitat? LOL I always thought maybe it was because I am dehydrated or something as to why I do now.

  10. Camille January 10, 2013 at 10:38 am - Reply

    It could also be because your hands and feet don’t produce oil, sebum is produced by sebaceous glands which are located near the hair follicle. The bottoms of your hands and feet are the only places that don’t grow hair (which is how we are able to have fingerprints) so they are probably less efficiently coated and when the oils are washed away they do not produce more their own to block the water from being absorbed.

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