Grab your glasses for this one, because we’re talking animal eyes. Eyesight is one of the most important adaptations animals rely on for survival. As humans, we know how much we depend on our eyesight to experience the world around us, but how do animals see the world?
Imagine you are soaring through the sky, flapping your wings over 10,000 feet above the ground. Even from all the way up there, you can spot your next meal. Eagle eyesight is six times sharper than a human's. From 2 to 3 miles away, they can detect their prey from up high. That’s like us seeing an ant from the top of a ten-story building! Eagles have two fovea in their retinas that function like binoculars, so they can focus quickly and zoom in and out, seeing incredible details from afar. A built-in eye shield is another trait they possess. This takes form as a clear eyelid that shields them from debris while flying.
Now picture yourself standing on a rocky hillside searching for a meadow to graze. You have to hop over rocks and navigate rough terrain while being constantly hunted. Mountain goats have rectangular-shaped pupils that give them a panoramic view of about 320 degrees. Their only blind spot is directly behind their head. This allows them to continue grazing while staying alert for any predators. The rectangular shape also allows for better light control which helps them stay vigilant at dawn and dusk. Additionally, they have 63 degrees of binocular vision that enhances their depth perception, which is vital for navigating the rocky, uneven terrain they call home.
Now, let’s jump into the ocean where you are swimming among the roots of a mangrove forest. You are a box jellyfish and have 24 eyeballs staring every which way. These eyes are clustered in groups of six. Four of the six are simple pits that detect light presence. The other two are more specialized, seeing images with light-focusing lenses. The upper eye is always pointed at the sky, no matter the orientation of the jelly’s body. Imagine it as a weighted ball dangling from a string whose purpose is to navigate the murky waters. Box jellyfish feed on small crustaceans called copepods that are attracted to the light patches within the mangrove canopy above them. In order to obtain their food, jellyfish need to stay near the canopy, which that upper eye helps them find. They can see the canopy up to 8 meters away; any more than that, and all they see is blue sky. The lower lens eye is there to help avoid obstacles as they navigate the vast ocean.
Finally, let’s return to land for a slithering surprise. You’re navigating around a dense rainforest, looking for your next meal, but–oh no!–it’s dark. Good thing you’re a snake with a pit organ allowing you to “see” in the dark. Snakes like pythons and boas use this organ like an antenna to detect infrared radiation (heat) from other organisms in their environment. Converted to electrical signals, it allows them to form a thermal image based on body heat. They can sense the direction and distance of prey from up to 1 meter away.
Animal vision is nothing short of extraordinary, with each species possessing specialized eyesight tailored to its unique needs. Whether it’s an eagle spotting prey from miles away or a jellyfish navigating the ocean with 24 eyes, the diversity of animal vision shows just how remarkable the natural world can be.
Maya Curlej is a Naturalist at Walking Mountains. She is grateful for her eyesight that allows her to see the beautiful mountains she gets to call home. Although, it’s not very good without her contacts.