If you are unfamiliar with a topic, it is often best to start with an encyclopedia, reference book or review article to gain a basic understanding of your topic as well as terminology used in the field.
Remember--books often have bibliographies that will lead to other sources.
Library of Congress subject headings
This Library, along with most academic libraries, classifies materials using the Library of Congress system. Go to the Library of Congress for a detailed outline of categories/call numbers.
You can use the following Subject Headings to browse OneSearch. The links can help you virtually browse the book shelves.
If you have a specific species that you want to search (animal, plant, etc.) start with a OneSearch keyword search using the name of your species, and then if necessary, limit your search to one of the subjects listed.