Mid-way down the length of the sperm whale skeleton are the bone structures of the whale’s flippers. On the underside of the whale, at the spot where the tail begins to taper, viewers can notice tiny leg bones suspended from wires. These limbs were the source of much fascination for Melville. Whereas the flipper of the living whale is paddle-like, the five-fingered bone structure hidden beneath the flesh resembles a human hand (Stubb, the second mate of the Pequod, jests that the whale wears “mittens”!). Likewise, the smooth, massive body of the whale completely obscures the hind leg bones buried under blubber.

For Melville, the stark contrast between the whale’s outward shape and inward skeletal structure proved that things aren’t always what they seem. For the scientists of Melville’s day, these appendages also seemed to suggest a curious anatomical link between whales and four-legged mammals. And, indeed, today we know that ancient whales descended from land quadrupeds who adapted their forelegs for swimming and whose hind legs eventually became unseen vestigial structures. While Ishmael is fond of insisting that the whale is a fish, the famous French anatomist Georges Cuvier felt these appendages were a reflection of its mammalian status. In words quoted by Melville in the opening “Extracts” section of the novel, Cuvier declares the whale a “mammiferous creature without hind legs.”