Sea snakes evolved from venomous land snakes that reinhabited the oceans about 5 million years ago. Recent research is finding the coloring of a sea snake can influence its vulnerability to algal fouling, which can significantly reduce their swimming speed (by about 20%). Their new life in water forced them to evolve traits that would allow them to survive better in aquatic environments: a paddle-shaped tail for swimming efficiency, valves to close their nostrils, and larger longs for oxygen. Most sea snakes are banded rather than one color, spotted, or stripy. To test whether or not color influenced algal fouling, scientist looked at sea snakes in the tropical Pacific Ocean. In this population, members of the same species could be any color form jet black to black and white banded. Over four years, researchers found that black snakes supported more algal cover than the black and white banded snakes. Next, they had to determine if this color really was the cause of higher algal levels. They suspended models (black, white, and white and black) in the middle water range. The results showed that color does directly influence that amount of algae that grew. They found that the black surfaces had the most algae, while white had the least. The consequence of having high algal growth is decreased swimming speed for the snake, with locomotor trials revealing a 20% decrease. At the same time, the algae may benefit the snake by providing more oxygen levels through photosynthesis. Apparently, the costs of being black is outweighed by some benefits.
Picture from-http://whyevolutionistrue.files.wordpress.com/2009/12/sea_krait1.jpg
Maybe this could be why there are some snakes that are banded black and white. They could get some of the benefit from the algae being on the black parts and can still have higher locomotive abilities than the all black snakes.
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