Largest tail

In absolute terms, the tail of the humpback whale (Megaptera novaeangliae) is the largest in the animal kingdom. Comprising two lobes (or “flukes”), a fully grown tail is as wide as a giraffe is tall, with one measured specimen reaching 17 ft 4 in (5.28 m), according to research by Nancy Stevick of WhaleNet.org.

In her WhaleNet post, Stevick references the original source: "The Whalebone Whales of the Western N. Atlantic Compared With Those Occurring in European Waters" (1904) by Frederick W. True – a statistical analysis of whaling in the major fisheries during of the 1800s. The book lists anatomical measurements for a number of whale species and remains a reliable source more than 100 years after its publication.