The European otter is between 70 and 80 centimetres long, and its tail another 40 centimetres, thickening towards the base. The male is somewhat larger and heavier than the female. Its head is flat and its ears are small and rounded. The sleek fur is glossy brown. The feet are both webbed and clawed.
The otter inhabits all kinds of freshwater areas, usually with thick surrounding vegetation. It sometimes inhabits coastal areas and can be found throughout Europe, Asia and northwest Africa.
Otters are solitary, territorial and mostly active at dusk or during the night. They are superbly adapted to living in water and swim and dive exceptionally well. Their ears and nostrils close when diving. The fur is made waterproof by an oily secretion. A thick undercoat traps a layer of air that prevents it from becoming waterlogged and keeps the body warm. Its covered dens and dry resting sites can be found in underground tunnels, tree roots, piles of boulders, shrubs and riverbanks, usually entered from beneath the water’s surface. Otters feed mainly on fish but also on water birds, frogs, crustaceans and molluscs.