Are you sure? Without knowing in what aspect the author was comparing, there's no way to determine if a hippo tail does or does not match the description. For all we know, he was referring to how they taste, or texture, or whatever.
For that matter, "a cedar" is not entirely clear, it may not be referring to a cedar tree. There may have been some object commonly made of cedarwood at the time which was known as "a cedar", but which is now obscure.
But the rest of the description -- the parts which *are* clear -- very much sound like an awed description of a hippo.
and whales don't have scales.
True, which is why (along with other parts of the descripton) leviathan was more likely a reference to the dragon myth, which already existed prior to the time of the authors of the Bible, and in regions not far from their own. They likely had heard the dragon myth, believed it, and added a reference to it to the Bible to describe one of God's more amazing creations.
;-)
;-)
The writer does say "moves". You know, like the swaying in the wind of the thin branches of a tree similar to, say ... a cedar
You are very creative.