From Science Daily: How the Sea Snake Got Its Stripes

I was delighted just by the title of this Science Daily story alone – due to its folk tale inspired headline – but was further intrigued about the suggestion that coloration of some sea snakes may cause them to be susceptible to the colonization of algae on their skin which may slow them down their swimming speed among other possible consequences. The excerpt and photo below are from the original Science Daily article which can be accessed here:

ScienceDaily (Apr. 14, 2010) — We all know that looks matter, and for snakes, a colour which works well on land has dramatically different results under water, according to a recent study by biologists from the University of Sydney.


Professor Rick Shine and Dr Adele Pile from the School of Biological Sciences have discovered a sea snake’s colouration can influence its susceptibility to algal fouling which can reduce swimming speed by up to 20 percent.

Their study, reported this month in Proceedings of the Royal Society B, sheds new light on how the transition from terrestrial to aquatic life has shaped the evolution of sea snakes.

Professor Shine said sea snakes evolved from venomous land snakes — such as the highly toxic tiger snake — who reinvaded the oceans around five million years ago.

“The fact that sea snakes have made the transition from terrestrial to aquatic life, makes them the perfect model to study evolution because we can compare traits between land snakes and sea snakes and hence identify selective forces unique to those habitats,” he said.

“The shift from land to water brought with it a new set of challenges, and sea snakes evolved unique physical traits which enabled them to survive in the aquatic environment — a paddle-shaped tail for swimming, valves to close their nostrils and large lungs to provide oxygen while under water.

“Another consistent attribute of sea snakes involves coloration: most are banded rather than unicoloured, blotched or striped. Fouling by algae has also been reported in several groups of sea snakes, and we wondered if maybe a snake’s colour could influence its susceptibility to this.”

To test this hypothesis, the scientists turned to a population of sea snakes in the tropical Pacific, in which members of the same species ranged from jet black to brightly black-and-white banded, and many patterns in between. Over a four-year period, the researchers examined free ranging individuals and found that black snakes supported significantly more algal cover than black-and-white snakes.

“There is clearly a balance of costs and benefits of algal accumulation, which is why we see a variety of colours in the population. For example, a covering of seaweed may slow down the snake and reduce its ability to obtain oxygen from the water directly through its skin, because the algae form a barrier. But on the flip side, the algae might increase the snake’s oxygen availability, because of algal photosynthesis, and hence benefit the snake.”

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