The diverse animal world generally referred to as “invertebrates” includes about 97% of the living species, in the museum it is displayed in two rooms on the first floor on the left of the stairs. The visit starts from the second room where almost exclusively marine animals are exposed. From the showcase  of the simplest organisms (Sponges, Corals, Echinodermata) you can move on to (clockwise) to six showcases which are devoted to the most important classes of Shellfish (Gastropods, Clams, Cephalopoda) and then to two showcases illustrating the different environment where  these shellfish live. On the next wall two showcases introduce us to the world of Arthropoda, particularly Arachnida and Crustacea, while a whole room is devoted to the extremely wide world of insects. The category of insects is the one with the highest quantity of species. About one million are known and they are spread in all of the Earth’s environments including waters, but curiously not in the sea. Two thirds of the Earth’s animal species are accounted for by insects almost half of which belong to the order of Coleopters.  One of the secrets of the evolutionary success of these Arthropoda is undoubtedly their ability to exploit the most diverse sources of food. For this purpose, they have developed different   mouthparts, as we can see in the enlarged reconstruction of the head of various insect orders displayed in one of the boards of the showcase devoted to the systematics.