I'll try to get some links - now I'm speaking from what I remember from University years and from visiting Moscow Paleontology Museum.
Narwhal - yes, absolutely. And as you could see, I tried to depict Triton Chariot as being pulled by dolphins.
A Whale Totem is also good idea.
As for Aboleth/Mamluk nation, I would love to see it, even if I don't like Aboleths as such. Probably, if it's ready, you could just post it in Mods subforum? Speaking of which, maybe this thread should be also moved there?