Dr.Jo's Amazing Science
There are millions of very tiny cracks in an elephant's skin.
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Why does an elephant’s skin wrinkle and crack?
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Elephant skin is very thick.
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It also has extra keratin a tough, protective protein.
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We have keratin in our hair, nails, and skin.
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Elephant skin gets thicker every day.
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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?
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Our skin replaces some of its top part, the epidermis, daily.
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The epidermis has up to 50 layers of thin cells.
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Cells on the bottom divide and make new cells.
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New cells push the top cells up, away from nutrients.
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The top cells die and flake off into the air.
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We shed around 50 million skin cells a day.
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Elephant skin gets thick because the top cells stick around​.
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Human vs Elephant skin thickness.
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Elephant skin is around 1 inch thick
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equal to a stack of 10 dimes
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Thickest on the back, trunk and legs.
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Human skin is around 2 dimes thick.
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Think about it
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Thick skin’s cracks keep an elephant in the hot sun cool.
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Where on the body might the skin be very thin?
Place your curser here for the answer.
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Skin is thinnest in parts not getting much hot sun.
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the belly
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the back of the ears
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Elephants spray water and mud on their backs.
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If elephant skin was smooth water would drip right off.
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The muddy water seeps through the cracks
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The water stays on the skin for more time.
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Epidermis
Dead cells come off
CNX OpenStax / CC BY (https://creativecommons.org/licenses/by/4.0) Labels added.
CNX OpenStax / CC BY (https://creativecommons.org/licenses/by/4.0)
Photo of human skin.
How does water in the cracks help cool the elephant?
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Water picks up heat from the skin.
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Carries it off into the air by a process called evaporative cooling.
Evaporative cooling defined.
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Water naturally moves off your skin into the air. (evaporation>)
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Water can pick up or absorb some heat from anything it is touching.
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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.
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
Simple demonstration of evaporative cooling .
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Wet one hand with water. Keep the other hand dry.
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Wave both hands in the air quickly.
a. Which hand feels cooler?
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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?