Sea Snakes Rediscover Color Vision Through Genetic Evolution
The annulated sea snake has evolved to regain color vision, perceiving a wider range of colors than its ancestors. Early snakes lost color vision during their adaptation to dim-light burrowing lifestyles, but sea snakes, which inhabit brighter marine environments, regained color vision. Two out of four intact copies of the snake's opsin gene SWS1 evolved a new sensitivity to longer wavelengths dominant in ocean habitats, enabling better color discrimination. This adaptation potentially helps sea snakes distinguish predators, prey, or potential mates against colorful marine backgrounds. The re-emergence of color vision in sea snakes contrasts the evolution of opsins in mammals like bats, dolphins, and whales, which experienced further opsin losses adapting to dim-light and aquatic environments.