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

Photo courtesy of Carol Kaelson. Christel Tucker, a Renton resident and flight attendant, stands at the wheel at Wheel of Fortune. Her episode airs Monday, Jan. 20.
Rentonite spins the wheel of her dreams

Local finds herself winning thousands on Wheel of Fortune

Photo courtesy of Patrick Dodd
                                Patrick Dodd and his father, Stan Dodd, at Hannegan Pass, Cooper Lake Trail. After Stan Dodd died in 2019, Patrick decided to dedicate 2020 to hiking and raising money to Fred Hutch Cancer Research Center.
He lost his dad, now he hikes for him

Local man turns to nature, blogging to fund cancer research

January’s Rotary Youth of the Month

Rotary members recognize three Renton School District high school students each month… Continue reading

Photo by Haley Ausbun. Have you visited the Highlands new brewhouse? The new Bickersons Brewhouse opened on Nov. 9. Two months later, Jan. 9, business leaders and the Renton Chamber of Commerce celebrated its opening with a ribbon cutting, featuring owners Frank Castro and Shaunn Siekawitch. Go bicker with the “Bickersons” at 4710 NE Fourth St., Renton.
Ribbon cut for new Renton brewhouse

Photo by Haley Ausbun. Have you visited the Highlands new brewhouse? The… Continue reading

Council gives Persson long, duly earned goodbye

Don Persson retires long Renton career

Photo courtesy of Handsome Devil Ink. Owners Maggie and Ryan Hammond with Bad Santa (center) at their annual Bad Santa Food Drive.
Bad Santa’s good charity

Local tattoo shop collects 800 pounds of food

Renton lights up for the holidays

A guided map to some of the best holiday lights in the city

Jewish students learn how to make menorahs

Home Depot partners with Renton Jewish Center for holiday projects

On Saturday, Dec. 14, 15 students were paired with Renton Police Department officers who volunteered their mornings to each kid’s family wish list at 2019 Shop with a Cop.
Renton kids get to holiday shop thanks to local police

The large police presence at The Landing Target was no crime response,… Continue reading

Photo by Haley Ausbun. Evergreen City Ballet dancers rehearsing at the Meydenbauer Center Theatre in Bellevue, Dec. 4.
From Evergreen’s Cavalier to Broadway and back home again

Artistic Director Bennyroyce Royon introduces himself with “The Nutcracker”

Luck be Renton’s lady

Chamber of commerce ends the year in style

Firefighters ring the bell for donations

Photo by Haley Ausbun. Renton Regional Fire Authority Firefighters volunteered to ring… Continue reading