The Department of Invertebrate Zoology houses some of the most extensive and historically important metazoan (and protozoan) collections available to researchers today. The extant Echinodermata, Bryozoa and Urochordata once housed within the Department of Marine Invertebrates are now within the Department of Invertebrate Zoology. The echinoderm collection is one of the largest in the world, containing more than 25,000 specimen lots. The Invertebrate Zoology collection today now includes most invertebrate phyla, with the exception of Mollusca. All arthropod groups with the exception of Hexapoda are housed in the Department. The Araneae collection is one of the largest in the world, with all major families represented. The crustacean collection is also among the most important in the world. Other strengths are the Acari, Opiliones, Myriapoda, Cnidaria and Porifera (specifically the hexactinellids). Specimens within the collection are dry and fluid preserved, tissues, on microscope slides or SEM preparations. The collection is now represented by well over 1 million specimens within approximately 350,000 lots and 17,373 Type lots (including over 10,750 primary Types).
The collection contain terrestrial and aquatic specimens from diverse geographical regions of the world. Many specimens were collected during the 19th and early 20th century expeditions, most significantly the Thayer to Brazil, the Hassler around the coast of South America, the Blake and Atlantis both to the Atlantic and Caribbean, the Challenger and Albatross to many Pacific regions, and the U.S. Geological Surveys of the Territories.
More recent marine acquisitions include North Atlantic specimens from various National Marine Fisheries Service cruises, the reference collection for the Massachusetts Water Resource Association Boston Harbor clean-up, the Howard Sanders deep-sea collections from the Woods Hole Oceanographic Institution and the deep water specimens from the Ocean Exploration Trust via the E/V Nautilus.