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Blue Whale Balaenoptera musculus Length 25-30m World’s largest living animal. Feeds on tiny, swarming planktonic crustaceans (krill). Adult has huge, streamlined body; bluish grey overall but mottled with greyish white. Seen just below water surface, body looks very blue. Flippers are relatively small. Single ridge extends from nostrils to tip of rostrum. Throat has 70-90 pleats that allow a huge expansion when feeding. Tail stock is thick and dorsal fin is small and set far back. Decimated by 20th Century whaling and possibly recovering.