References for Scientific Illustrators
Ichthyology and Marine Life
National Audubon Society Field Guide to North American Seashells
by Harald A. Rehder, Harold A. Rehder
National Audubon Society Field Guide to North American Fishes, Whales, and Dolphins
by Herbert T. Boschung, Daniel W. Gotshall (Editor)
National Audubon Society Field Guide to Tropical Marine Fishes : Of the Caribbean, the Gulf of Mexico, Florida, the Bahamas, and Bermuda
by C. Lavett Smith
National Audubon Society Field Guide to North American Seashore Creatures
by Norman A. Melnkoth, Norman A. Meinkoth
Web Sites:
Online Image Databases 
Fish
Tree of Life Web Project, provides scientific name for species
Google Image Search, searchable database of images