Happy Monday to everyone! Since today is day 15, I want to share 15 interesting facts with you about eyes that I’ve just found in National Geographic!

1. First, we sometimes praise people who have big eyes, right? Well imagine if they had eyes the size of a watermelon! Squid eyes are about the size of this fruit. According to Wikipedia, the average diameter of squid eyes is 25cm (like a basketball!), and this is considered to be the animal with the largest eyes.

Curious facts about eyes - fish eye

2. Continuing with marine animals... imagine you're a fish, you've been struggling all day to avoid being eaten, looking for food, looking for a partner with whom to procreate or swimming against the current ... how would you feel at the end of the day? Tired! But fish cannot close their eyes! Does this mean they cannot sleep? No, fish rest in other ways. Here's more.

sleeping fish

sleeping fish

3. The weight of the human eyeball is equivalent to five €0.50 coins! Which adds up to 7.5g.

fish eyes

4. Ostriches eyes are bigger than their brains!

ostriches have bigger eyes than their brains

5. Some people can hear their eyeballs moving.


6. The blink of an eye is equivalent to 2/5 of a second! This means 0.4 seconds

7. People blink 10,000 times on average per day.

curious facts about eyes - blink

8. Dolphins always sleep with one eye open. They are not the only animals that rest in this way!

dolphin eyes

9. Butterflies are able to see ultraviolet light!

butterfly eyes

10. Chameleons can look in different directions at once. This is a gift that, if you remember from the post a few days ago, American soldiers were trying to replicate with their new contact lenses.

chameleon eyes

11. As we know, the sun can burn our eyes. Precisely for this reason, we earnestly recommend using quality sunglasses with protection. Remember, cheap things can turn out expensive, and with your eyesight there’s no way back.

baby eyes

Finally I’d like to share some more curious facts from other biology blogs:

12.  Some people have red eyes: these are albinos, whose lack of pigment means you can see the blood circulating through the iris and the back of their eyes.

albino eyes

13. The difference between men and women? Only 0.5% of women are colour blind compared with 8% of men. And what about size? To my surprise, the size of eyes is very similar, men’s eyes only being half a millimetre bigger.

women vs men eyes

14. Did you know that blue eyes are more common than green eyes?

green eyes

15. If you have blue eyes, it means you share an ancestor with everyone else in the world with blue eyes. Interesting, don’t you think?

blue eyes

See you soon!


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