It’s interesting that God devotes a whole chapter to describing the leviathan. Gill writes about this in his introduction.
INTRODUCTION TO JOB 41
A large description is here given of the leviathan, from the difficulty and danger of taking it, from whence it is inferred that none can stand before God, Job 41:1; from the several parts of him, his face, teeth, scales, eyes, mouth and neck, flesh and heart, Job 41:11; and from various wonderful terrible things said of him, and ascribed to him, Job 41:25.
Canst thou draw out leviathan with an hook?…. That is, draw it out of the sea or river as anglers draw out smaller fishes with a line or hook? the question suggests it cannot be done; whether by the “leviathan” is meant the whale, which was the most generally received notion; or the crocodile, as Bochart, who has been followed by many; or the “orca”, a large fish of the whale kind with many teeth, as Hasaeus, it is not easy to say “Leviathan” is a compound word of than the first syllable of “thanni”, rendered either a whale, or a dragon, or a serpent, and of “levi”, which signifies conjunction, from the close joining of its scales, Job 41:15; the patriarch Levi had his name from the same word; see Gen 29:34; and the name bids fairest for the crocodile, and which is called “thannin”, Eze 29:3. Could the crocodile be established as the “leviathan”, and the behemoth as the river horse, the transition from the one to the other would appear very easy; since, as Pliny says (a), there is a sort of a kindred between them, being of the same river, the river Nile, and so may be thought to be better known to Job than the whale; though it is not to be concealed what Pliny says (b), that whales have been seen in the Arabian seas; he speaks of one that came into the river of Arabia, six hundred feet long, and three hundred and sixty broad. There are some things in the description of this creature that seem to agree best with the crocodile, and others that suit better with the whale, and some with neither;
or his tongue with a cord which thou lettest down? into the river or sea, as anglers do, with lead to it to make it sink below the surface of the water, and a quill or cork that it may not sink too deep; but this creature is not to be taken in this manner; and which may be objected to the crocodile being meant, since that has no tongue (c), or at least so small that it is not seen, and cleaves close to its lower jaw, which never moves; and is taken with hooks and cords, as Herodotus (d), Diodorus Siculus (e), and Leo Africanus (f), testify; but not so the whale.