Sharks are cartilaginous fish, and the so-called cartilaginous fish, as the name suggests, is cartilage like the bones of sharks, rays and other fish. At present, there are 350 species of sharks that have been recorded, usually inhabiting water surfaces up to 3,000 meters deep, and are an active pelagic fish. Most large sharks are fierce and flexible fish in the ocean. Sharks have long been thought to be afraid of red. Are sharks really afraid of red? Shark vision is the shark's reflection of the image of the external environment, the resulting vision is produced by the optic nerve cells to receive external stimuli, and then the stimulation is transmitted to the central nervous system, the shark thus sees objects.
Fish have the ability to distinguish colors. Biologists have used red, white, and gray bowls to experiment, in the red bowl is loaded with bait, fish often eat bait in the red bowl, and in the white and gray bowls do not find the bait, it forms a conditioned reflex, and later in the red bowl without bait it also swims to find the red bowl. Sharks, however, cannot distinguish colors, and unlike the eyes of other fish, the eyes of sharks contain a large number of cylindrical cells in their retina, with no cone-like cells. Cylindrical cells are highly sensitive to the brightness and darkness of light, and can even feel light with small intensity and short wavelength, while cone cells have the ability to feel strong light and distinguish colors. Cone cells are cells that act during the day, while cylindrical cells act at night
of cells. As a result, sharks can better distinguish between bright and dark backgrounds, but not colors. Ichthyologists have conducted color tests on several wrinkled-lip sharks, throwing nine different colors of wood blocks, such as red, yellow, orange yellow and green, into the experimental pool, and when the wrinkled-lip shark swims past the wooden blocks, there is no abnormal behavior. It can be seen that most sharks are not visually developed, can not distinguish colors, and can not talk about sharks afraid of red