Why human pollution is causing this snake to lose its stripes

Researchers have found that a sea snake’s appearance has been drastically changed by the effects of living close to humans.

Turtle-headed sea snakes live on coral reefs in the Indo-Pacific and have characteristic black and white stripes across their bodies. But the research, published in Current Biology, found snakes living in areas with more human activity nearby became entirely black.

The sea snake in black
(Claire Goiran)

The study found that the colour difference was due to the snakes’ exposure to pollution – as their black bodies allowed them to more effectivley rid their bodies of contaminents such as arsenic and zinc when shedding their skin.

In contrast to those exposed to pollution, snakes which lived in pristine parts of a reef were found to still have their white bands.

The effect of darkening skin in animals due to pollution is known as industrial melanism – and the graph and images below show the effect urban-industrial areas had on the appearance of snakes.

The snakes and a graph
(Current Biology/ Elsevier Ltd)

This darkening of skin has been shown to appear in a number of species living close to humans.

“The animals I study continue to astonish me,” said Rick Shine of the University of Sydney. “I think it’s remarkable to find industrial melanism in organisms as different as moths and sea snakes!”

Sea snake with bands
(Claire Goiran)

The study, lead by Claire Goiran of the Université de la Nouvelle-Calédonie, started after the researchers noted that darker feathers – such as those of urban pigeons – “enhance a bird’s ability to shed pollutants”.


 

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