Can Fish See in The Dark?
The deeper parts of the sea are dark because sunlight cannot reach there. How do fish living there swim without bumping into each other?
Fish can actually “see” with the use of special sensory organs. When you see a fish next time, look for a line running along its skin, from the gills to the tail. All fish have this mark, called the “lateral line “. All along this line there are openings in the skin. These openings allow water vibrations to reach sensory organs which are located under the lateral line. These sensory organs, in turn, are connected to the fish’s nervous system and are very sensitive to even the slightest vibrations in the water. These vibrations help the fish to know if another fish is approaching, what direction it is coming from and how far it is.
So a fish can navigate expertly in the total darkness by “seeing” with her sensory organs.