As a guideline to create these resource pages, we used the "Classification Of Life" in Appendix Three from the 4th edition of Biology by Neil A. Campbell. The textbook states "This appendix presents the taxonomic classification used for the major groups of organisms discussed in this text; not all phyla are included. Plant and fungal divisions are the taxonomic equivalents of phyla. The classification reviewed here is based on the five-kingdom system..."
Use the dictionary and encyclopedia links to help define and, in some cases, provide the scientific name for your chosen organism(s).
NCBI Taxonomy Browser -- Find your organism lineage, fast!
Do a search at NCBI to retrieve the complete lineage of your species. This database does allow searches by common name and is very complete. If you do not find your species, try a variation on the name, ex: crayfish instead of crawfish or mangroves vs. mangrove. If you need guidance, use the online help sheet.
Dictionaries & Encyclopedias:
Define your terms - why are both spiders and lobsters called arthropods?