Plants Database is fabulous ...try to find your producer here.
A-Z Animals is great for information about consumers.
AnimalBytes from Seaworld is perfect for your assignment, but it does not include all animals.
GVRL -- Use this at school (or look at page 16 of your student planner for the password for GALE). A comprehensive animal database.
Decomposers Read this -- it will help you figure out what to pick.
Nature's Recyclers: Vultures and fungi, maggots and bacteria. Oh, yes!