Well Slurgs are fairly simple animals so my guess is that there wasn't much change needed for their speices. There probably able to adapt to just about any climate and eat just about anything which leaves no reason for evolution.
Hmmm... as for Gabbits well they resemble earths frogs in a way, living in water, occasionaly going on land but having to go back to the water to lay eggs. They where probably some type of reptile on land but moved back to the water for certain reasons, or it could be the other way around?
