One for the dedicated. A long chapter describing all the known species in Melville's day, focussed on their utility for burning oil.
This chapter, often omitted in abridged versions of the novel, has its very own wikipedia page http://en.wikipedia.org/wiki/Cetology_of_Moby-Dick
ContentsI. Sperm whale (Physeter macrocephalus), the most important prey of Nantucket whaling fleet, which operated principally in the Pacific Ocean and Indian Ocean. The notorious fictional white whale Moby Dick in the novel is of this species, and is based on the real-life sperm whale Mocha Dick in the South Pacific in the 1840s. Because of lack of observations of the blue whale at that time, Melville asserts inaccurately that the sperm whale is the largest creature on Earth.
II. Right whale (several species of the genus Eubalaena of the family Balaenidae), also known simply as the Whale, the Greenland whale, the Black whale, the Great whale. Melville claims this whale was the first to be regularly hunted by human beings and is famously known for providing baleen, which was also known as "whalebone" at the time. The oil of this whale was commercially known as "whale oil" and was of inferior grade to that of the sperm whale. During the middle 19th century, it was the principal prey of the whaling fleets of the United Kingdom and the Netherlands, which operated largely in the North Atlantic and Arctic Ocean.
1 Description
2 Melville's classification
2.1 I. The Folio Whale
2.2 II. The Octavo Whale
2.3 III. The Duodecimo Whale
3 Beyond the Duodecimo