We hope you’ve had an amazing Sunday funday wherever you are in the world. We’re going to finish it off with day 10 of November Knowledge cool croc facts before we shut the world out for the evening after our day of cleaning trash from mangrove 🙂
Crocodilians have incredible eyesight on the surface of the water.
Their eyes are designed for aerial distance viewing, and binocular vision gives them great depth perception with a wide field of view. Unlike our eyes which are firmly bolted in place, crocs can sink their eyes into their skull to protect them when attacking prey or fighting with each other.
During the day, the pupil closes up to a tiny slit, whereas at night it fully dilates so wide it almost looks like it takes up the entire eye and will close up immediately again when light hits it.
The general assumption is all species see in full color, but researchers in Australia have documented slight differences in the color sensing cone cells between freshwater and saltwater species because of the difference in color wavelengths found in salt and fresh water environments, with the photoreceptors in the retina of freshwater crocs leaning towards longer, redder wavelengths.
Crocs have 3 eyelids on each eye. 2 blackout eyelids from top to bottom, and a 3rd translucent eyelid that goes sideways from front to back called a nictitating membrane. Nictitating membranes vary in clarity from relatively clear with a little marbling, to cloudy with minimal or zero vision.
Inside the eyes, guanine crystals reflect and amplify light at night from sources like the moon and stars allowing them to see quite well in the dark. Underwater, vision is believed to be lacking focus, although how much they can see is going to vary depending on the clarity of water and the clarity of their nictitating membrane. Obviously a croc in murky water with cloudy membranes is going to have very limited vision, and they’re not going to see anything at all under water during the darkness of night.