The most distinctive feature of this rather elusive cetacean is its distinctive humped appearance when it breaks the ocean's surface to breathe (2). This is caused by the wide hump or ridge on the dolphin's back, from which the dorsal fin emerges (3). The Atlantic humpbacked dolphin is a robust-bodied marine mammal (2), typically slate grey on the sides and back and light grey on the underside (3). It has a long, narrow, distinct beak (2) (3), broad flippers that are rounded at the tip, and a broad tail fin, deeply notched in the centre (2). It is thought that, like the better known and closely related Indo-Pacific humpbacked dolphin (Sousa chinensis), male Atlantic humpbacked dolphins are larger than females (2) (3).