What kind of animal would Gatsby be?

My first thought is that Jay Gatsby has a great deal in common with the Mimic Octopus, a species from the region made up of the tropical parts of the Indian Ocean and the warm western Pacific Ocean, where they connect near Indonesia. This species of octopus is able to mimic the color and texture of other animals so as to blend in or camouflage themselves from predators. They also even know how to mimic the shape of other forms of sea life so that they cannot be recognized for their true selves.
These amazing abilities make me think of Gatsby because he has attempted to hide his own origins with fantastic stories—like those he tells Nick at first about traveling around Europe and living like a prince while trying to forget his tragic past—and he tries to adopt the habits and attitudes of the old moneyed, upper class who lives in East Egg. Old money folks were born into money and they inherit their fortunes; they do not have to work to earn them. Unfortunately for Gatsby, he cannot ultimately change who he really is, and his flashy clothes, ostentatious home, and circle of loud and vulgar friends betray him as new money: someone who was not born into money but, rather, has had to work for it.
Tom Buchanan grows suspicious of Gatsby and begins to look into his identity and business connections as a result of Gatsby's inability to ultimately blend into upper crust society. That being said, I guess the Mimic octopus is actually a little better at blending in than Gatsby; they do a better job of evading predators, I think, than Gatsby does (if we consider Tom to be his predator). Gatsby eventually is eliminated by Tom, his disguises ineffective against Tom's malice and jealousy.