Mr. Alfred Kahl was a German schoolteacher who took up microscopy mid-life and became a leading authority on ciliated protozoa. He taught English, French, and Natural History in Hamburg, Germany. He first became interested in ciliophora when his daughter, Lucia, was studying protozoa at the Hamburg Tropical Institute. In a burst of scientific productivity that lasted just nine years, he published 1800 pages of scholarly work, in which he described 17 new ciliate families, 57 genera, and about 700 previously unknown species. During his brief career as a protozoologist, he redescribed and illustrated nearly all the species of ciliates known in his time, and fit them into a taxonomic scheme that remains influential today.

Relevant to the biota of the Gulf of Mexico, Alfred Kahl has published the following:

Kahl, A. 1930–1935. Urtiere oder Protozoa. I. Wimpertiere oder Ciliata (Infusoria). Parts 18, 21, 25, 30 in F. Dahl, ed. Die Tierwelt Deutschlands. G. Fischer, Jena, Germany.