Leupold Genesis part 52 verse 21

21. And God created the great sea monsters and each one of the creeping creatures with which the waters teem after their kind and every winged bird after its kind; and God saw that it was good.

Verse 21 in its relation to v. 20 furnishes a very excellent example as to how the account of what actually was done furnishes an invaluable commentary upon the original command of what was to be done. We ourselves would, as a rule, not have discerned what the original commands involved if the following statements had not made the full breadth of the original command plain. As far as the "swarms of living souls" of v. 20 are concerned, we are given to understand, first of all, that these swarms included not only the smaller fry among the fish but also "the great sea monsters" (tanninim), a word whose root indicates a creature of some length. In this category are found not only "whales," as A. V. translates, but all larger marine animals like sharks and, no doubt, also crocodiles: Nor do we hesitate to include under this head amphibians like the saurians of every class and description. Then the account specifically mentions what we have translated, "each one of the creeping creatures!" For here, apparently, nephesh has the common meaning of "individual" or "one," and what the account wishes to emphasize is that of the teeming multitudes of these marine creatures each one owed its existence to God's creative work. On this meaning of nephesh see K. S. 302a. The term rendered "creeping" (romeseth) literally implies "moving lightly about" or "gliding about" (B D B). Difficulty in fitting in these terms led to our rendering "creeping," which strictly does not apply to movement in the water. Another distinctive thought conveyed by this half of the verse is the added assertion that these creatures appeared "after their kind," a phrase not new but as important in its bearing as above. (v. 12) and allowing for no transmutation of species [Leupold here conflates the biblical concept of 'kind' with the scientific term 'species. The two are not the same thing. It is 'kinds' that do not transmute. Kinds may exist at the genus or family level. The definition of species is such that transmutation is readily achieved]. In the second half of the verse it is applied also to the birds.

The expression "winged bird" is literally "bird of wing," kanaph, "wing," being a genitive of quality and the phrase' as a whole what is known as an "ornate epithet" (K. S. 335 a) similar to our expression "yellow gold." Of course, birds have wings. But here, besides, where the very broadest of class distinctions are being made, without a doubt, the expression is meant to include every type of being that has wings--the small and the large, and not only what we call birds.

But on the whole an entirely new type of being has come into existence, creatures that breathe and are animated and have power of their own volition to go from place to place. To give existence to such is the peculiar prerogative of God and is a monumental, epoch-making achievement that deserves to be described by the verb "and He created" (wayyibhra') as the opening verse does.