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 department became the large and comprehensive collection it is today.
Many specimens were collected on the Hassler and Thayer expeditions, and by U.S. Fish Commission vessels including the Albatross and the Blake. Considering US collections, the MCZ is second to only the National Museum in echinoderm primary type holdings.
The echinoderms remain the vast majority of the departmental holdings, joined by bryozoans, brachiopods, and urochordates.