Dr. Universe explains why we have eyelashes

Ask Dr. Universe is a science-education column from Washington State University.

  • Thursday, October 11, 2018 4:32pm
  • Life
Illustrations by Rob McClurkan

Illustrations by Rob McClurkan

Dr. Universe: Why do we have eyelashes? -Rebekah W., 12

Dear Rebekah,

Across the animal kingdom, we see all kinds of eyelashes. They come in different sizes, shapes and textures. They also come in different colors, though most fall somewhere between black, brown, and blonde. All of them are actually hairs and the scientific term is “cilia.”

When humans look in the mirror, they usually see eyelashes lining both their upper and lower eyelids. Sometimes lashes fall out, but humans can grow them back. The lashes are just thick enough to keep things like small particles of dust away from their eyeballs. But there are some animals with even thicker lashes.

If you were a camel or a llama, you would have a lot more eyelashes. Camels actually have three eyelids protecting each eye. Two of those eyelids have bushy eyelashes. They help keep the sun and sand out of the camel’s eyes.

Giraffes also have some pretty full eyelashes. Giraffes like to eat from big prickly trees called acacias. One of the challenges of eating from a tree with thorns is that you might get your eye poked. Eyelashes help the giraffes sense if they are getting too close to the thorny branches.

While eyelashes come in different shapes and sizes, they all have a sense of touch. It makes them what scientists call tactile organs, said my friend and veterinarian Kevin Kaiser. He studied at Washington State University and now helps animals at the Animal Eye Clinic of Spokane.

Kaiser said eyelashes help the body recognize when something might cause harm to the eyes and tell the eyelids to shut. While a lot of animals have eyelashes, some animals also have other kinds of hairs on their face to help them sense the world. Some of these animals include cats, like me.

Horses have something similar. In addition to upper eyelid lashes, they have very long hairs around their eyes called vibrissa. Meanwhile, dogs have two to four rows of eyelashes along the upper eyelid and none along the lower eyelid.

Hair is unique to mammals. In fact, some animals don’t have eyelids at all. For example, some kinds of fish don’t have eyelids or lashes. They live in an environment that keeps their eyes wet. Water gets in their eyes, but it doesn’t seem to bother them. They even sleep with their eyes wide open.

Animals that do have eyelashes also have something in common when it comes to the size of their lashes. A few years ago, scientists studied about 20 animal specimens at the American Museum of Natural History in New York. They took a close look at the eyelashes. They found that most eyelashes in the animals were about one third the width of the animal’s eyeball. It’s an eyelash length that appears to be just the right size to protect an animal’s eyes.

Sincerely,

Dr. Universe

More in Life

Passport Day tomorrow, Oct. 5 | King County

Go to Renton to apply or renew your passport.

This time of year, it’s all about the harvest

The fourth week of August is time to reset for the coming… Continue reading

Scott Kreidermacher, left, and Lara Randolph, right, hold up the food that remains from a busy day at the Free Grocery Store, a new project from nonprofit Sustainable Renton, on Monday, Aug. 19. Photo by Haley Ausbun.
Free grocery store to combat food waste

A small Renton nonprofit hopes to help homeless and keep food from the landfill

Registering to vote online or in-mail ends Monday

In-person registration is available up until Election Day, Aug. 6.

Cruz the Loop and Return to Renton Benefit Car Show set for July 6, 7

Hot Rod weekend, downtown, will have some street closures.

Join author Kurt Armbruster for a discussion of his latest book, “Pacific Coast, Seattle’s Own Railroad” at 6 p.m. May 16 at the Renton History Museum, 235 Mill Ave. S. Courtesy photo
Upcoming events: Pacific Coast Railroad history lesson; coffee with Renton cops

Symphony: Bellevue Youth Symphony Orchestra Spring Masterworks Concert will highlight Tchaikovsky’s Symphony… Continue reading

Renton Rotary’s Youth of the Month for May

Five Renton students were selected as May 2019 Youth of the Month to finish off the school year.

Gardeners love our veggie-friendly Western Washington climate

Here are the most incredible edibles to grow now.

A look back at Black River

Renton History Museum hosts event with Seattle writer and natural history expert David Williams.

It is a busy time in the garden with planting

Near the end of April the nurseries will be overflowing with color.… Continue reading