Natural connections: underwater eyes | Columns


The low gray clouds of an approaching thunderstorm made the humid afternoon even darker. Preparing to get home from work, I strapped on my bike helmet and strapped my pannier to my rear rack. My sunglasses, however, slipped into the back pocket of my hi-vis vest. It was just too dark to wear them comfortably.

A few kilometers later, I came to regret this decision.

The county road should be repaved soon, and I hit and swerved through cracks, rough edges and loose gravel. When a truck passed me, barely about to pass despite a straight and clear road, its tires sent a jet of sand and dust. Blinking, I could feel bits of fine grain in my eyes.

Wouldn’t it be great, I thought, if I could have put on some goggles just as the truck passed?

In fact, many animals have goggles that they can engage and store at will. This third eyelid is called the nictitating membrane. This scientific word has a great rhythm, and I love having the students say it with me: nik-ti-tey-ting.

We have upper and lower eyelids, I explain, and these animals also have transparent or translucent eyelids that move horizontally.

Birds of prey like peregrine falcons use their nictitating membranes during high speed dives to protect their eyes from dust and debris in the air, and also as windshield wipers to clean that dust from their eyes and keep them safe. wet. Nictitating membranes are often engaged at the point of attack, and sometimes also while chicks are being fed. In fact, most birds, even small tits, protect their eyes this way.

After a few more miles of blinking opaque lids, my eyes felt good again. At that time, the bridge over the Namekagon River was in sight. Even without the sun, the afternoon was uncomfortably hot and the crystal clear river water sparkled refreshingly. At the last second, I made up my mind, checked my helmet mirror for cars, and swerved into the river dock.

The water was only knee deep in it, but sitting on the rocky bottom I was able to cool off up to my shoulders.

I revel in the contact of the current supporting and massaging my back, and let my gaze relax in gentle fascination with the patterns of light and the bed of eelgrass rippling beside me like the hair of a river nymph.

When something hit my bare ankle, I looked into the water and tried to squint past the glare of the surface. Even with polarized sunglasses now actually on my face where they belonged, I couldn’t get the shapes to resolve into anything identifiable. Was it a fish? A crayfish? A floating leaf? A river monster?

I got up and walked towards shallower water. Yet all the moving shapes were camouflaged under the glare of the surface. Oh sure, I could have put my face in the water and opened my eyes to see better, but then the debris would seep in and my contact lenses would rub off. I’ve always struggled to seal swimming goggles, and I didn’t have any in my bike bag today anyway.

Once again, I thought longingly about the nictitating membranes. Aquatic animals have them too. Exotics like sharks, sea lions, crocodiles and manatees, but also our inhabitants, like beavers, frogs, fish, turtles, ducks and loons can close their third eyelids underwater.

While many mammals (like us) have lost this amazing adaptation, lions, cats, camels, polar bears, rabbits, aardvarks and those busy beavers still have this cool trick in their pocket.

As I stood there wishing for a way to see underwater, a sudden burst of light hit me. My new Olympus Tough camera, with its waterproof case, was stored in my basket. In a few minutes, I was hitting a record and plunging it into the current. I couldn’t aim at him or hold him still in the surprisingly strong flow, but it was better than nothing. I pulled it out, stopped recording, and hit play.

On the LCD screen, dozens of small, cigar-sized fish, each with a dark stripe from eye to tail, streaked over mini hills of sand and among green plants. In a square, chartreuse green seaweed undulated like soft feathered boas in a graceful dance.

On the surface all I could see was sparkling light and impressionistic shapes and colors. I could feel the fish nibbling at my ankles, but I could hardly see anything. The world the camera revealed was full of movement, light, color, and also life. Soft green down protruded from the rocks, ribbon-shaped plants playfully rippled, and many sizes of these fish easily slipped through the bubbles my wrists stirred as they resisted the flow.

I might not have my own built-in swim goggles, but my underwater “eye” is quite special in its own way: I can share what it sees with you!

Visit my blog or the Museum’s YouTube channel to watch the fish and seaweed dance. It can really open your eyes to what is underwater!

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available for purchase at and also in your local independent bookstore.

For over 50 years, the Cable Natural History Museum has served as your connection to the Northwoods.

The museum is now open with our exciting exhibition The Mysteries of the Night. Connect with us on Facebook, Instagram, YouTube and to see what we’re doing.


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