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Millions of cracks
elephant skin cracks cropped.jpeg

There are millions of very tiny cracks in an elephant's skin.

Why does an elephant’s skin wrinkle and crack?

  • Elephant skin is very thick.

    • It also has extra keratin a tough, protective protein

      • We have keratin in our hair, nails, and skin.

  • Elephant skin gets thicker every day.

    • The thick, skin folds and breaks into millions of tiny cracks.

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This image has been cropped to show the larger cracks.


António F. Martins, Nigel C. Bennett, Sylvie Clavel, Herman Groenewald,

Sean Hensman, Stefan Hoby, Antoine Joris,

Paul R. Manger and Michel C. Milinkovitch

/ CC BY-SA (

Why is the elephant skin so thick?

  • Our skin replaces some of  its top part, the epidermis, daily.

  • The epidermis has up to 50 layers of thin cells.

  • Cells on the bottom divide and make new cells.

    • New cells push the top cells up, away from nutrients.

    • The top cells die and  flake off into the air.

    • We shed around 50 million skin cells a day.

  • Elephant skin gets thick because the top cells stick around​.

Human vs Elephant skin thickness.

  • Elephant skin is around 1 inch thick

  • equal to a stack of 10 dimes

  • Thickest on the back, trunk and legs.

  • Human skin is around 2 dimes thick.

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human skin cross section.png
Elephant skin is thick
  • Skin is thinnest in parts not getting much hot sun.

    • the belly

    • the back of the ears

Think about it

  • Thick skin’s cracks keep an elephant in the hot sun cool.

  • Where on the body might the skin be very thin?

Place your curser here for the answer.

Elephants spray water and mud on their backs.

  • If elephant skin was smooth water would drip right off.

  • The muddy water seeps through the cracks

    • The water stays on the skin for more time.



Dead cells come off

CNX OpenStax / CC BY ( Labels added.

Photo of human skin.

water spray

How does water in the cracks help cool the elephant?

  • Water picks up heat from the skin.

  • Carries it off into the air by a process called evaporative cooling.

Evaporative cooling defined.

  • Water naturally moves off your skin into the air. (evaporation>)

  • Water can pick up or absorb some heat from anything it is touching.

  • When the water goes into the air it takes the heat with it.

Evaporative cooling


This is a nice video that explains the elephants skin cracks.

See how cracked skin helps elephants stay cool/Decoder.



Martins, A.F., Bennett, N.C., Clavel, S. et al. Locally-curved geometry generates bending cracks in the African elephant skin. Nat Commun9, 3865 (2018).


Lillywhite, H. B. & Stein, B. R. Surface sculpturing and water-retention of elephant skin. J. Zool. 211, 727–734 (1987).


Martins, A.F., Bennett, N.C., Clavel, S. et al. Locally-curved geometry generates bending cracks in the African elephant skin. Nat Commun 9, 3865 (2018).*

Simple demonstration of evaporative cooling .

  1. Wet one hand with water.  Keep the other hand dry.

  2. Wave both hands in the air quickly.

         a. Which hand feels cooler?

Simple demonstration of evaporation. 

1.Fill a plastic cup halfway up with water. 

             a.Use a marker to mark the waterline on the outside.

2.Leave the cup in a sunny window.

             a.Draw a new line each day at the water line.

             b. What is happening to the water?

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