The Invertebrate Zoology collection contains approximately 400,000 slide-mounted and alcohol-preserved specimens of terrestrial, freshwater, and marine organisms from many parts of the world, but with emphasis on the United States and Mexico. The general collection contains significant material from Texas, other parts of the United States, Central America, and the Galapagos Islands.
Maintained as a separate unit is the biospeleology collection. This collection contains specimens obtained from caves in essentially every county in Texas and state in Mexico known to have caves.
The marine invertebrate collection includes significant voucher material from projects in Alaska and the Texas Gulf Coast.