Beluga whale  (Delphinapterus leucas)

The snow-white beluga whale is one of the most distinctive of all cetaceans (a group that includes, dolphins, whales and porpoises). The stocky body ends in a particularly small head, and adults develop their striking white colouring as they mature (2). Belugas lack a dorsal fin, their genus name 'Delphinapterus' means 'dolphin-without-a-wing' (3) (6), but there is a ridge of toughened skin along the back that tends to be more pronounced in mature males (6). Unlike most cetaceans, belugas have an extremely flexible neck and can turn their head almost 90 degrees to the side; their lips are also flexible, forming a variety of facial expressions (3). Belugas use a wide range of vocalisations such as clicks, grunts, squeals, screeches and whistles (6). These sounds can be heard through the hulls of ships and the beluga was nicknamed the 'sea canary' by early Arctic sailors (3). They have a very thick layer of blubber which may be up to 15 centimetres thick that provides insulation in the freezing arctic waters (6).