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A turtle-headed sea snake. Image Credit: Claire Goiran

Sea snakes are losing their bands of colour because of pollution

  • BY Angela Heathcote |
  • August 10, 2017

Sea snakes are experiencing rapid evolutionary change causing them to turn black in order to concentrate pollutants in their skin. Scientists have also found that the sea snakes are shedding their skin more frequently.

SEA SNAKES, recognisable by their speckles and bands of black and white colour, are turning entirely black in order to cope with water pollution.

Scientists explained that the black coloration enables a snake to concentrate trace-element pollutants in its skin, while also prompting the snakes to shed their skin more frequently than is considered normal.

While the findings show that sea snakes are capable of adapting to polluted waters, according to herpetologist Rick Shine from the University of Sydney, who co-authored the study, there are limits to what the sea snakes can tolerate. Rick told Australian Geographic that sea snake populations are plummeting and therefore we should be looking at long-term solutions, specifically, taking better care of our oceans.

The study, published in the journal Current Biology today, analysed the colour differences in turtle-headed seas snakes living in the coral reefs of the Indo-pacific region by looking at the contents of the snakes shed skin where they found traces of arsenic, zinc and other industrial chemicals.

Additionally, researchers found that sea snakes living in more human-populated, polluted areas, with markedly different coloured skin to those that occupied the cleaner, much healthier parts of the reef had developed a way to cope with the environmental pollution.

This concoction of chemicals and the resulting black colouration is also known as ‘industrial melanism,’ a term first coined to describe the coping mechanisms developed by various animals to adapt to the conditions brought about by the industrial revolution.

What exactly is ‘industrial melanism’?

Rick explained that industrial melanism refers to the process by which animals evolve an increased frequency of black coloration in polluted areas.

“The most famous example is the peppered moth in the UK, after soot from the Industrial Revolution blackened the trees,” he said. “The original light-grey moths were so conspicuous that birds ate most of them; but a mutant black form was harder to see, and so increased in frequency.”

However, this new study is the first to examine how and why industrial melanism occurs in a marine organism. “Darker skin attracts the spores of algae, so black snakes soon are covered in seaweed – and so, have to shed their skin frequently to get rid of these fouling organisms,” Rick said.

While it’s positive that the snake is adapting to its predicament, black skin has offset effects. “Black skin attracts more algal spores, creating drag as the snake swims around.”

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