Why do elephants have big ears?!

Hi Lili!

When I was in college, I read a book called Why do elephants have big ears?. It's one of my favorite books ever. It explains all kinds of interesting evolutionary adaptations and how they work. How elephant ears and blood flow in bird legs and thermoregulation, warmbloodedness, coloration, etc! In that book, I also learned that on a single island, one cat was responsible for the extinction of something like 19 bird species.😔

The book explains that woolly mammoths didn't have big ears but elephants do because elephants live in warm climates and keep their bodies cool. It's particularly difficult to do this when you're huge because the ratio between an elephant's surface area and volume is lesser than that of something small, like a mouse. What I mean by that is that if you were to skin an elephant that weighed two thousand pounds and compare the carpet it's skin made up vs. if you were to skin 2000 lbs of mice and make a carpet, the mouse carpet would be much larger! Because per unit volume, each mouse has more surface area, which means that there is more space for heat to escape. In an elephant, they have more volume, more elephant body making heat, and relatively less space on it's skin to escape. So guess what they have?! Huge, well-vascularized (a lot of blood vessels) ears!

Their ears increase their surface area and because they're particularly thin, when you send blood to the ears, it allows that blood to be closer to the outside and so that blood can give off it's heat and cool down before it goes back to the rest of the body!

Unlike elephants, woolly mammoths who lived in cold environments, had much smaller ears! Isn't that cool?!?

Next time you see an elephant flapping it's ears in the heat, or perhaps next time you see a particularly large person with huge ears, maybe it'll trigger some interesting questions to arise in your head

Love,

Molly

P.S. Here's the next letter