Adders are the only snake found within the Arctic Circle, specifically Scandinavia and Russia. Adders, perhaps more than any other snake, blur the traditional boundaries between cold- and warm-bloodedness.
The most obvious adaptation for life so far north is evident in early spring, when basking adders appear almost to stretch out each of their ribs and flatten their bodies like pancakes. By doing this, they increase the surface area in contact with the sun’s rays, turning them into efficient reptilian solar panels.
Northern adders are also helped by their reproductive strategy. Whereas many snakes lay eggs in naturally warm spots, such as compost heaps, adders retain the developing embryos in their bodies and ‘give birth’ to live young.
The babies are therefore insulated from the extremely cold temperatures that eggs laid outside probably couldn’t withstand. There’s also their diet. Small mammals thrive in the northern springtime. One successful strike with its venomous fangs and an adder can live happily for weeks – even months – through any any late cold snaps.
Did you know adders, as well as being the snake that lives the farthest north, are also the highest-living snakes in the world, found at 2,500m above sea level?
Main image: adders are the furthest north living snakes, inhabiting the Arctic circle © Getty Images
