Melanistic form of the common adder (Vipera berus) on a beach. Melanism is a condition where an excess of the skin pigment melanin produces animals with a dark-coloured skin. This snake has large fangs with which it bites its prey (mainly small mammals), injecting its venom. Found in northern and central Europe and Asia, it hibernates in winter, being active from April to September. Photographed in April, on Chesil Beach, Dorset, UK.