1. Cornea and Lens:
- The cornea and lens of a fish's eye are specially adapted to focus light underwater. The cornea, which is the clear outer layer of the eye, is more curved than in humans, allowing it to bend (refract) light more effectively in the water.
- The lens of a fish's eye is also more spherical and can change its shape to fine-tune the focus of light on the retina.
2. Retina and Photoreceptor Cells:
- The retina, located at the back of the fish's eye, contains specialized photoreceptor cells called cones and rods.
- Cones are responsible for color vision and work best in bright light conditions.
- Rods are more sensitive to dim light and help with vision in low-light environments.
3. Optical Window:
- The space between the cornea and the lens of a fish's eye is filled with a fluid known as the aqueous humor.
- This fluid creates an "optical window" that helps transmit light efficiently from water into the eye, minimizing distortions caused by the change in refractive index between water and air.
4. Tapetum Lucidum:
- Many fish species have a reflective layer called the tapetum lucidum behind the retina.
- The tapetum lucidum helps to enhance low-light vision by reflecting light back toward the retina, increasing the chances of capturing photons and forming an image.
It is important to note that while fish can generally see underwater, their visual capabilities can vary depending on the species, water clarity, depth, and specific adaptations to their environment.