Invertebrates (Invertebrata) represent 96% of all animal species. Invertebrates are distributed on land, in seas, and in fresh waters. They do not possess neither vertebra, neither chord.

Section hall of invertebrates exposes 1696 shells, 257 preparations fixed in liquid, and 242 dry preparations. Hall distributes showpieces in systematic order, reflecting evolution of fauna. Exposition consists of the most scientifically, culturally and historically interesting showpieces from Lithuania and other countries. Part of the exposition has been collected by founder of the museum professor T. Ivanauskas.

Rather considerable amount of exposition, such as tropical sea shells, has been presented by P. Šivickis, as well, as sea shells were presented by Australian Lithuanian E. Liutikinenė in 1973 – 1976. 300 sea and land snails, as well as bivalve mollusc shells from V. Matuzevičius collection were exposed in 2013. Painters V. & V. Bručas rearranged and renewed diorama “Fauna from the bottom of warm seas” in 2013.