The collections in the Department of Invertebrate Zoology comprise about 500.000 lots preserved in ethanol, dried or on microscope slides. The oldest specimens were collected during the 18th century. A considerable part of the collections were acquired towards the end of the 19th century and in the early 1900s, when several expeditions, e.g. the Vega expedition and the Swedish South Polar expedition brought material to the museum. At present, most new specimens are acquired as a result of on-going research projects at the department. Animals with hard shells, tests or spicules etc., e.g. molluscs, corals and sponges, are also kept in the dry collection.
Many invertebrates are microscopic.
Therefore a part of the collection is mounted on microscope slides, either as whole mounts or as serial sections. The mollusc collections contain about 280.000 dry lots and about 40.000 lots in alcohol. Marine molluscs are well represented from the Arctic and Antarctic, the North Atlantic ocean and southern South America. For land and terrestrial molluscs, Scandinavia and the Baltic countries are well covered. A large number of type specimens have been isolated and registrated.