Exciting Study – Deep-Sea Fish Are Seeing Color in the Darkness

Humans and other vertebrates are color blind in dim light, but as new studies have found out, some deep-sea fish possess a unique color vision in complete darkness, not even in dim light. This possibility is given by the fact that the species are featured with some genetic adaptation to the environment. After many analyzes on many species of fish, they had come with some conclusions.

How Can Deep-Sea Fish Have this Capacity?

After biologists have analyzed 101 fish species, three lineages of deep-sea fish have been found. The species are living up to 1.500 meters below the surface, and have this unique genetic adaptation for color vision in darkness. Of course, having an advantage like this seems logical, because they are searching for food, mates and especially to avoid predators.

Moreover, Zuzana Musilova of Charles University in Prague, who is an evolutionary biologist, says that their eyes are much more sensitive than other species or vertebrates. If we think about vertebrates, we find out about two types of photoreceptors cells in the retina. The two photoreceptor cells are rods and cones. The rods are used for dim light, and no colors are being detected, while the cons are engaged in bright-light conditions and with them, we perceive colors.

Also, the rods cells are containing a single type of photopigment which reacts to light and is called rhodopsin. This rhodopsin gene has been found in 13 species of deep-sea fish, and they are capable of detecting colors. A particular case is the Silver Spinyfin, a deep-sea fish that has 38 copies of the rhodopsin gene. This Silver Spinyfin is around 30 cm long, has large eyes, silver and circular body, and it is eating plankton and shrimps.

Finally, Silver Spinyfin’s food is situated somewhere around 400-1.200 meters, and light reaches down to 1.000 meters. So the deep-sea fish can also receive light from other creatures that emanate light. The study was published in the Science journal.

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