Snake-Dragon

I believe that the snake in Genesis is Satan and the dragon which are the same. Satan, devil, dragon are the same. The lake of burning sulfur is prepared for Satan.

Reading bible should be done carefully since many of its entry could be like what you said "symbolical". Generally in the bible Dragon only represents Satan but he did not ever disguise it for real. You may read it like "he disguise as a dragon" but if you read the whole paragraph, it only relay this phrase in a symbolical way since there is no dragon in real life.