Carl Oplinger is professor emeritus at Muhlenberg College. Throughout his forty-one years there, he taught courses in zoology, ecology, and environmental science. For several decades, he conducted courses in marine ecology at The Bermuda Biological Station. He lives in Emmaus, Pennsylvania.
Robert Halma taught botany, ecology, and geology at Cedar Crest College in Allentown, Pennsylvania. Today he is professor emeritus and the former curator of the college's arboretum.