Pilsbry Chair of Malacology, Academy of Natural Sciences of Philadelphia and Professor, Department of Biodiversity, Earth and Environmental Science, Drexel University. Commissioner, International Commission on Zoological Nomenclature. Editor for Mollusca, World Register of Marine Species and MolluscaBase.
His research focuses on the origins and magnitude of diversity of the Mollusca, with active research currently in the Philippines (marine and terrestrial mollusks) and Jamaica (land snails). He uses biodiversity databases to better document the known diversity of mollusks and to estimate their total diversity.