The reason is that a larger retina with a larger aperture is able to detect more photons because of its larger area. This makes them more effective at seeing i

The reason is that a larger retina with a larger aperture is able to detect more photons because of its larger area. This makes them more effective at seeing in the darkness of the deep ocean. It's the same reason why cameras with full-size sensors are more light-sensitive and create higher quality images.