From 1948 to 1958 he was a senior physicist in the Radioactivity Division of the National Bureau of Standards (NBS) and was enrolled part-time at the University of Maryland.
[3] With the aid of a recommendation by W. F. Libby, Seliger became a Guggenheim Fellow for the academic year 1958–1959, which he spent in the biology department of Johns Hopkins University.
This was the beginning of his outstanding achievements in the study of bioluminescence in fireflies, bacteria, phytoplankton, fish, and ctenophores.
[4] Seliger, as part of a team of Johns Hopkins scientists, studied more than 100 different species of fireflies in Maryland and on the island of Jamaica.
"[4] In the work for which he is perhaps best known, Seliger's firefly research helped other scientists harness bioluminescent molecules to identify key sections of DNA for genetic studies.