There are some preliminaries to settle.
First: The uncertain, unsettled condition of this science of Cetology is in
the very vestibule attested by the fact, that in some quarters it still
remains a moot point whether a whale be a fish. In his System of Nature,
A.D. 1776, Linnaeus declares, "I hereby separate the whales from the fish."
But of my own knowledge, I know that down to the year 1850, sharks and shad,
alewives and herring, against Linnaeus's express edict, were still found
dividing the possession of the same seas with the Leviathan.
The grounds upon which Linnaeus would fain have banished the whales from
the waters, he states as follows: "On account of their warm bilocular heart,
their lungs, their movable eyelids, their hollow ears, penem intrantem
feminam mammis lactantem," and finally, "ex lege naturae jure meritoque."
I submitted all this to my friends Simeon Macey and Charley Coffin, of
Nantucket, both messmates of mine in a certain voyage, and they united in
the opinion that the reasons set forth were altogether insufficient. Charley
profanely hinted they were humbug.
Be it known that, waiving all argument, I take the good old fashioned
ground that the whale is a fish, and call upon holy Jonah to back me.
This fundamental thing settled, the next point is, in what internal respect
does the whale differ from other fish. Above, Linnaeus has given you those
items. But in brief, they are these: lungs and warm blood; whereas, all
other fish are lungless and cold blooded.
Next: how shall we define the whale, by his obvious externals, so as
conspicuously to label him for all time to come? To be short, then, a whale
is A SPOUTING FISH WITH A HORIZONTAL TAIL. There you have him.
However contracted, that definition is the result of expanded meditation.
A walrus spouts much like a whale, but the walrus is not a fish, because he
is amphibious. But the last term of the definition is still more cogent, as
coupled with the first. Almost any one must have noticed that all the fish
familiar to landsmen have not a flat, but a vertical, or up-and-down tail.
Whereas, among spouting fish the tail, though it may be similarly shaped,
invariably assumes a horizontal position.
da: H. Melville, _Moby Dick_