Most of the time, snapping a photo as someone closes their eyes calls for a re-do, but here at the Aquarium, sometimes those photos can be, well, eye-opening! Let’s zoom in on a macro view of some of the oddest and out-of-this-world eyes within our walls.

Eye Can’t Even

Boasting one of the most complex sets of eyes in the animal kingdom, mantis shrimp have spectacular vision. For context, humans have two types of photoreceptors in our eyes, rods and cones (Photoreceptors are special cells in our eyes that detect light and then send electrical signals to our brain to interpret that light into vision!). That sounds pretty complex… until you hear that mantis shrimp have 12 types of photoreceptors!

These crustaceans have two compound eyes that can move independently from one another. Thousands of ommatidia, which contain photoreceptors, form each eye to create trinocular vision — yes, TRInocular. This extremely sensitive vision and depth perception gives them an advantage while hunting. As mantis shrimp may “spear” or “smash” to hunt, their quick and powerful movements require this expert marksmanship!

Eye Understood the Assignment

Have you ever seen a bird (like a bald eagle or white ibis) blink? Or, have you ever witnessed how reptiles (like alligators) keep their eyes open underwater for long periods of time? Thanks to up-close views of animals here at the Aquarium, you may get a glimpse at their translucent eyelids, known as nictitating membranes!

A nictitating membrane is a third eyelid — transparent or translucent — that offers protection and a moisture barrier, but allows the animals to still use their vision. If you’re wishing you had a nictitating membrane right now, you may be surprised to learn humans have the remnants of one! Ours is called the plica semilunaris (it’s that small fold on the inner corner of your eyes)!

Eye Can See Clearly Now

Do snakes have spectacles? You may chuckle at that question, but allow us to focus in on the answer: While they aren’t prescription, snakes do have a translucent scale (called a brille) over each eye! This acts in a similar fashion to the nictitating membrane, providing both protection and a means to retain moisture in the eye.

Fun fact: The brille is always present on a snake’s eye. However, we humans may only notice it during a snake’s shedding cycle, when it turns cloudy and blue. If you ever see a snake with seemingly blue film over their eyes during your visit to the Aquarium, you can impress your group with this new fun fact!

Eye Do Declare

Frogs are well known to have large, bulging eyes; think of Kermit the Frog, whose eyes are represented by ping pong balls! Their eye position — protruding from atop the head and set far apart — allows them an incredibly wide field of vision. Researchers have discovered frogs can see color in low-light conditions (even when it’s so dark that humans can’t see anything)!

Frogs use their eyes for more than just seeing, though. Have you ever caught a glimpse of a frog eating? If you look closely, you’ll notice they blink as they swallow. As bizarre as it may seem, many frogs actually use their eyeballs to help them swallow food! As they swallow, they retract their eyeballs downward to the roof of their mouths, helping prey slide down their throats with ease.