As of November 2009, the Invertebrate Zoology Collection at the KU Biodiversity Institute contains more than 2000 lots, including more than 150 lots of type specimens. A strength (with more than 1500 lots) is "sea anemones" in the loose sense (Cnidaria: Anthozoa: Actiniaria, Zoanthidea, and Corallimorpharia) from all over the world, with notable holdings from the Galapagos Islands and the tropical western Pacific.

Several hundred lots of medusozoans (Cnidaria: Hydrozoa, Staurozoa, Scyphozoa and Cubozoa) are from Japan, the United States, and Panama. Molluscs include 160 lots of Kansas mussels (Mollusca: Bivalvia: Unionoida and Veneroida) and 85 lots of land snails from Kansas and Florida (Mollusca: Gastropoda). The nearly 200 lots of arthworms (Annelida: Oligochaeta) are from around the world, and include many type specimens.

The collection also includes nearly 100 lots of Kansas crayfish (Arthropoda: Malacostraca: Decapoda), 27 lots of tapeworms (Platyhelminthes: Cestoda), and a few lots of brittlestars (Echinodermata: Ophiuroidea), sea slugs (Mollusca: Gastropoda: Nudibranchia), scaphopods (Mollusca: Scaphopoda), and sponges (Porifera), plus 1 lot of Nematoda. Most specimens are wet-preserved and there are histological slides of some. Some specimen data can be accessed from the link below. Collections of Kansas molluscs and crustaceans made by or referred to by Leonard are in the U. S. National Museum of Natural History.