Today starts Shark Week. a week of celebration of sharks and their value to the world. Here is a little Shark Vision Trivia:
Shark Eyesight: Sharks have poor vision, but acute other senses that allow them to detect small amounts of vibrations and chemical changes in the water.
Sharks’ Eyes: Did you know that Shark Eyes are like ours? The retinas contain both rod and cone cells. The Rods allow for the shark to see light and dark and cones allow for the seeing of color. Shark eyes also have a cornea, lens, pupil and iris.
Sharks Can See In The Dark: Sharks have a tapetum lucidum. Tapetum lucidum is a layer of mirrored crystals behind the retina. Light that might have escaped detection through the retina can get detected a second time. Sharks may not get the full acuity, but are sensitive to an image. This adaptation allows Sharks to see up to ten times greater than humans in clear water and in the dark.
Sharks’ Eyes Are Protected: When attacking prey, shark eyelids protect the eye. A dictating (clear) membrane covers the eyes when a shark bits. The Great White Shark does not have a nictating membrane, but rolls their pupils back for protection when feeding.
Shark Eyes Are Varied: Shark eye and pupil size can vary depending on the layer of ocean they inhabit. The largest eyed sharks live 0-1000 meters below the surface. Below that surface (1000-4000 m) sharks have smaller eyes with larger pupils. (less light). Sharks that feed on large, fast moving prey have larger eyes than those who feed on sedentary prey.
Resources: Shark Savers