The invertebrate collections comprise about 500.000 lots preserved in ethanol, dried or on microscope slides. We house a large slide collection with preparations of nematodes and tardigardes.
Molluscs constitutes more than half of the invertebrate collection, 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. The dry collections are mainly uncatalogued; those in alcohol are manually catalogued with catalogue number and genus-species entries in the catalogue.
Computer cataloguing is proceeding in an application of Filemaker Pro, developed by Sabine Stöhr.
In the Swedish Museum of Natural History there is a fairly large collection of mainly marine nematodes prepared by C.A. Allgén and covered by publications from 1925 to 1960. A large number of type specimens have been isolated and registered. However, due to drying the slides are often in a bad or very bad condition.
There is also a collection of marine nematodes from the Swedish west coast and Norway (Bergen area and the Trondheimfiord) prepared by Margareta Hendelberg during the 1970s.
There are also slides of soil nematodes from various Swedish localities and Antarctic nunataks prepared by Sven Boström and Björn Sohlenius.
Several new species of bacterial feeding soil nematodes described by Sven Boström are kept in the type collections.
In the Swedish Museum of Natural History there is a small number of slides collected by G. Thulin in 1909-11.
There is also a collection prepared by B. Sohlenius from Swedish pine forest soil (Gästrikland in the middle of Sweden), from the City National Park of Stockholm (the Ecopark) and from the Stordalen mire (Abisko).
There are slides with tardigrades collected from nunataks on Dronning Maud Land in Eastern Antarctica by three Swedish expeditions (SWEDARP) during the period 1991-97.
In the Swedish Museum of Natural History there is a large number of polychaetes deposited, both from earlier 19th century expeditions and from more recent collections.
Type material include animals described by Kinberg, Malmgren, Hessle, Bergström, Wesenberg-Lund, Arvidsson, Hartman, Sigvaldadottir and Pleijel.
Several Swedish zoologists specialised in the study of free-living flatworms during the 20th century. Most of the material they collected are now in our collections.
Among the most energetic collectors were Einar Westblad, who collected in Scandinavia, the British Isles and the Mediterranean and Tor G. Karling, who collected in Scandinavia and in the U.S.A. In the collections are also a considerable portion of the known species of free-living flatworms from South America, collected by Ernst Marcus.
The Swedish South Polar Expedition (1901-1903) brought material from the Antarctic, and Sixten Bock collected in the Pacific.
The collections of the Swedish Museum of Natural History include material of all five recent echinoderm classes (sea-lilies, seastars, brittlestars, sea urchins, and sea cucmbers), most of it collected by the great expeditions of the 19th and early 20th centuries. These expeditions covered mainly the Nordic/Arctic area and South America.
The type collection holds almost all types of the 71 species described by A.W. Ljungman, but material of other authors is also present.