Blue Whale (Balaenoptera musculus)

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The largest animal known to have lived. The longest individual on record is a female measured at a South Georgia whaling station in the South Atlantic at 33.58 m; the heaviest on record is a separate female taken in the Southern Ocean on 20 March 1947 at 190 tonnes. It is a rorqual: a lunge-feeding baleen whale that engulfs a volume of prey-laden water comparable to its own body mass and then filters it. The species is divided into subspecies whose migrations differ so much that treating "the blue whale migration" as one route is misleading - Antarctic, pygmy and putative northern Indian Ocean populations behave differently. IUCN assesses the species as Endangered, with an estimated 5,000-15,000 mature individuals and an increasing global trend, while individual subspecies range from recovering to critically endangered.