Turtle head snakes darken due to pollution

Usually people and sea snakes try to avoid each other. Reptiles prefer life in remote regions. They are also poisonous, so people also do not seek to find them. But tortoise-headed sea snakes are a completely different story. They are not poisonous and live near cities. For example, in the city of Noumea, the capital of the French part of New Caledonia in the Pacific Ocean. The proximity and safety of these snakes have made them excellent targets for research that has been going on for 20 years. Some results have puzzled scientists.

Caring for hygiene

In their work with these aquatic reptiles, scientists noticed the difference between tortoise snakes that lived near cities and individuals of the same species that lived far from people. The "city" snakes were darker, and there were fewer distinctive stripes on their skin. Researchers believe that the main reason for this unusual color is pollution.

Water flows from the sewers of large cities into the habitats of urban snakes. Biologists have previously observed how environmental pollution changes the color of animals. Probably the most famous example of "industrial melanism" is the Birch moth butterfly. During the industrial revolution in Europe, this butterfly acquired a darker color to fit into a new, more polluted background.

But sea snakes do not need to hide from someone in a polluted environment: camouflage is important when the animal remains stationary. Snakes often swim, swimming through corals. They do not need a “black” background.

In company with pigeons

Another version of scientists: a change in the color of the snake can be caused by the fact that the darker melanin is associated with toxic trace elements in the body of the snake. When a snake sheds its skin, it also gets rid of pollutants in its body. The darker the skin, the more pollutants snakes can squeeze out of their bodies.

The only example of such adaptation in vertebrates in an urban environment before the story of tortoise-headed snakes was pigeons: dropping dark feathers, these birds also try to make life less toxic in megacities.

But the fact that snakes have figured out how to escape from city dirt does not justify people: reptiles cannot adapt forever. Although snakes are very resistant to changing conditions, there is a limit to any adaptation. Therefore, scientists continue to sound the alarm.