Something to add on to the randomly generated species the random creature would be the base of the species and the most common but there could be small variation on that some would be slightly larger then others some might have larger horns which may cause them to do more damage various small things like that
Pretty sure this was already announced/confirmed, at least something similar anyway. Go check out the thread with all the announced stuff here: http://community.playstarbound.com/index.php?threads/list-of-announced-game-information.450/