February 19 - National Lashes Day

nPosted on February 19, 2020

Key points

Today is probably a marketing opportunity for people who sell mascara and false eyelashes. But we can take advantage of there being a National Lashes Day to ask two questions:
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n(1) What are eyelashes for?
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nand (2) Do other animals have eyelashes?
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nEyelashes, like eyelids, have evolved to protect eyes. Eyelashes protect from dust, sand, small insects, etc. They are sensitive to touch, so when something comes near the eye, the eye closes reflexively. (That means that a reflex closes the eye – you don’t have to consciously realize, “Oh, oh, something just touched my eyelashes, I’d better close my eye!” Obviously, that would take too long!)
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nSince eyelashes are hair, and only mammals have hair, pretty much only mammals have eyelashes. However, some animals that live in the water have lost almost all of their hair, including their eyelashes. Dolphins and whales, for example, don’t have eyelashes.
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Camel

Elephant

Giraffe

White rhino

Wolf

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nYou may have noticed that I said “pretty much” only mammals have eyelashes. A closeup of an ostrich will tip you off why I fudged on the “only mammals” bit; a few kinds of birds have “eyelashes” that are made of modified feathers, not hair. These bird lashes look similar to mammals’ lashes – and they serve the same protective function.
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