Few Deep-Sea Fishes can see Colour in Low-light Conditions

A new visual system is discovered in the deep-sea fishes which lets them see the colors even in low lights. They can detect their predators even when it is nearly dark at the bottom of the sea. A team of researchers which was led by Zuzana Musilova and Walter Salzburger from the University Of Basel, Switzerland has found about this visual system in deep-sea fishes. These fishes have a highly sensitive vision. Till now, 13 such species with such a vision system are now known. These species can discern particular wavelengths of color at distances reaching 1,500 meters i.e. about 5000 feet in the deep seas, where light hardly reaches. This capacity allows these fishes to detect bioluminescent organisms for their food.

To know how this visual system works, some basic concepts behind this vision need to be reviewed. The vertebrates having such a capacity of vision, whether human of fishes, use unique light-sensitive photopigments for converting the light into some kind of signal that the brain ca relay as vision. These photopigments have proteins called opsins inside them which can absorb light. Rod opsins are used in the darkness while cone opsins are used in the brightness. The opsins of cones and rods absorb light at a particular wavelength, but the color vision arises when multiple cone opsins interplay. Majority of vertebrates have just one single rod opsin. In low-lights, they are color blind virtually. As per the marine biologists, the deep sea fishes were also of a similar category, however, the latest studies don’t support this.

Salzburger said in a statement that the deep-sea fishes have been able to develop the multiple rhodopsin-based visions independently of each other many times. This vision is particularly used to detect bioluminescent signals. These abilities are helpful to the fishes to detect predators, prey or their own family members in the deep seas. Some fishes are equipped with a number of distinct rod opsin photopigments and not just a single opsin. These rod opsins work together to let the fish hone in wide-ranging visual wavelengths.

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