Whales

1:21 And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.

Here whales are distinguished from "every living creature that moveth", as opposed to last verse's "moving creature that hath life".  Is it because whales don't move?  Aren't alive?  Birds, too.

Other translations say "sea monsters" instead of "great whales".

Unlike the previous verse, this one says "after their/his kind".  This phrase was used to describe seeds of trees and grains before: an apple tree has apples containing apples seeds which grow into apple trees, etc.  It doesn't seem to make much sense here, but by analogy, it's talking about birds having bird babies and creatures having creature babies.  Maybe.

That would almost call for a very odd interpretation of this, in which multiple generations of creatures are being described here.  Which raises the issue of whether the abundance is the water creating lots of creatures; or whether it's the creatures, once created, breeding abundantly.  Grammatically, abundantly is modifying "bringing forth", which the water is doing; but we've seen enough not to entirely trust the grammar.