If you follow I think it's Buddhist philosophy on re-incarnation then 1. yes it is possible, and 2. becoming human again would actually be a down grade in enlightenment. You work to human and then seek to go beyond, I would consider whale beyond. Of course that is my personal opinion and not fact; the ultimate state is to exist solely in an energy form where you can be one with the universe from what I've heard.
May you be blessed in all that you do, just ask me first if you are going to do unto me.
I fear nothing and everything.
A fool thinks he knows everything a wise man admits he knows nothing.
Einstein on his theory of relativity: "The Actions of a man in an airplane are being done at the same speed as a man doing similar, or the same actions in a house. The only difference is the speed at which the house is moving compared to the speed of the airplane."
I may be wrong in what I say, I will however defend the core of it if I have heard stated that the basic is correct.