The Marine Invertebrates Department holds approximately 5 million specimens of marine invertebrates, emphasizing mollusks and crustaceans of southern California, Baja California, and the eastern Pacific in general. Included are worldwide collections in selected mollusk and crustacean groups. The collection holds 134 primary and 700 secondary type specimens.
Recent growth in the collection includes vernal pool invertebrates, largely from California's Central Valley region, and the acquisition in 1988 of more than 80,000 lots of benthic marine invertebrates donated by the Marine Review Committee of the California Coastal Commission.
This is the largest collection of southern California benthic marine invertebrates in existence.