In 1859, Louis Agassiz founded the Museum of Comparative Zoology (MCZ). Shortly after the completion of the first wing of the Museum of Comparative Zoology in 1860, nearly 100,000 specimens were already part of the Department of Invertebrate Zoology (IZ). These specimens came from existing specimens already owned by Harvard, those that L. Agassiz brought with him from Switzerland in 1847, and those that he either collected or purchased after his arrival in the United States. Many students of L. Agassiz were named as assistants and given the responsibility of arranging various collections, five of which, in 1860 were devoted to invertebrates. Currently under the direction of Curators Gonzalo Giribet and Mansi Srivastrava the collections continue to grow, and are a valuable resource to scientists, students, and others.
In July 2016 the Department of Marine Invertebrates (MI) which housed the echinoderms, bryozoans, and urochordates merged with the Department of Invertebrate Zoology. The echinoderm collection began in 1859 with the founding of the MCZ. Under the direction of Alexander Agassiz, Hubert Lyman Clark, Theodore Lyman and others the collection became the large and comprehensive collection it is today. Considering US collections, the MCZ is second to only the National Museum in echinoderm primary type holdings.