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.

Attribution:  https://commons.wikimedia.org/wiki/File:Skin_African_elephant.png

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 (https://creativecommons.org/licenses/by-sa/4.0)

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
 
  • 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.

Human%20skin%20photo%20peeling%20top_edi
African_bush_elephant_(Loxodonta_african

Epidermis 

Dead cells come off

CNX OpenStax / CC BY (https://creativecommons.org/licenses/by/4.0) Labels added.

Photo of human skin.

 

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.

 

MORE INFORMATION.

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

See how cracked skin helps elephants stay cool/Decoder.

https://www.youtube.com/watch?v=cqIQ-LS-DmM

TECHNICAL REFERENCES

 

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). https://doi.org/10.1038/s41467-018-06257-3

 

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). https://doi.org/10.1038/s41467-018-06257-3

 

https://www.nature.com/articles/s41467-018-06257-3*

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?