The term 'Arctic Cetacean' refers to a group of aquatic mammals that inhabit the Arctic Ocean and its surrounding seas. This group includes the NARWHAL (7 letters), ORCA (4 letters), Shamu (5 letters), WHALE (5 letters), and PORPOISE (8 letters). The NARWHAL is a medium-sized WHALE with a long, spiral tusk protruding from its head. The ORCA, also known as the Killer WHALE, is the largest member of the dolphin family. Shamu is a name commonly used to refer to Orcas in captivity. Whales are large marine mammals that are divided into two suborders: baleen whales and toothed whales. Porpoises are small toothed whales that are closely related to dolphins.