Animal Scene - 2021-09-01




Do brittle stars have eyes? No, they don’t, but they can perceive light and dark with the presence of opsins. This light and dark perception is enough for some brittle stars to survive, move around, and find shelter. However, the brittle star species Ophiocoma wendtii is unique from the rest of its kind. It is a brittle star that can see viable but blurry images, allowing the creature to seek shelter more efficiently during the day. Opsins are light-sensitive proteins found on the bodies of the brittle stars that serve as a substitute for eyes and allow brittle stars to see their environment. There are about 13 sequences of opsins that provide extraocular vision to the brittle star. However, the opsins are affected by the activity of chromatophores in some species. Chromatophores contract and relax to produce color in pigmentcontaining cells. It is hypothesized that chromatophores affect the availability of light to the opsins, preventing other species of brittle stars to see viable images the same way that the Ophiocoma wendtii can. Brittle stars have plenty of opsins on their arms and body that allow them to sense light and dark. This gives them visually-guided motion to find cover and move around. Scientific evidence suggests that opsins may be affected by the activity of chromatophores in brittle stars: Some species of brittle stars, especially red ones, are unable to see any viable image at all and are only able to perceive light and dark.


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