A-Z Animals is great for information about consumers.
AnimalBytes from Seaworld is perfect for your assignment, but it does not include all animals.
Born Free: Keep Wildlife in the Wild presents information about biomes and the animals that live there.
Decomposers Read this -- it will help you figure out what to pick.
The Fungal Library has information on fungal decomposers.
Nature's Recyclers: Vultures and fungi, maggots and bacteria. Oh, yes!