Dangerous Animals

It would be cool to add common predator animals to the different biomes. There is a polar bear in the ice biomes, so why not add alligators to the swamps, bears to the forests, sharks to the oceans, baboons to the jungles, and/or mountain lions to the mountains. Ultimately, it would be cool to have more of a living ecosystem in the world of Minecraft where more animals could interact with each other and players.