From the back of the box:
Evolution never stands still. You have probably already created poisonous carnivores, hid them in burrows and attached complex cooperation chains. Did your animals gain fat, fell into hibernation or lost a tail or two?
The cards in this box open up new horizons for your creatures. You can now hide them in sturdy shells, squirt out ink and even teach them to fly. Now you'll need to think thrice before attacking an innocent looking animal. It could very well be a dangerous carnivore, just waiting for you to take its bait.
With this expansion, the game has become so much more diverse, the total amount of possible creature combinations is actually more, than the estimated number of species on our planet!