Hohenwart's collection of conches
In this exhibition corridor, we can see two large display cases with numerous splendid and most interesting gastropod and bivalve shells. This is part of the collection donated in 1831 to the Carniolan Provincial Museum by Franz Hohenwart, as the President of the Museum Curatorium. It comprises about 5,000 specimens from the entire world and is, apart from Zois' collection of minerals, one of the fundamental collections of the Slovenian Natural History Museum.
Molluscs form a substantial group of non-segmented invertebrates, which include chitons, gastropods, operculate snails, bivalves and cephalopods. Today, the world is inhabited by some 128,000 mollusc species, of which 105,000 are gastropod and by some 20,000 bivalve species.
Distribution of molluscs is influenced by climate, temperature, sea currents, water depth, salinity, construction of soil, the manner of reproduction and other factors. Distinct related species live in different zoogeographical regions. The highest number of specimens in Hohenwart's collection come from the Indopacific region.
Although all the exhibited specimens deserve our attention, let us have a special look at the shells of the cephalopod called Nautilus(Nautilus pampilius). These are exhibited in the left display case, at the bottom left. Nautilus, which lives in the Indian Ocean, is today the only living cephalopod with external shell in the world. Its relatives are the long extinct ammonites as well as still living squids, cuttlefishes and octopuses. Under this, we can see the Mother-of-pearl Shell, Pinctada maxima, which used to be widely collected in nature due to its wonderful pearls. This is the reason why it has been almost extirpated in certain places. Today, they are being bred, in captivity, especially in Japan, where they are artificially stimulated to form pearls. Here let us add that a pearl can be created in every shellfish with sufficiently developed mother-of-pearl. When a foreign particle ends up between its two shells – such as a tiny stone or a parasite – the shellfish encircles it with the mother-of-pearl. In 1864, a well known Slovenian Nautilus Mother-of-pearl Shell Nautilus pampilius Pinctada maxima nature historian and collector found, in a stream near Borovnica, a shell of freshwater clam with a pearl inside it. Pearls, however, are no exception even in oysters, Mediterranean mussels and scallops.
Let us also mention the shells of gastropods from the group of cowries , Cypraeidae. You can have a look at their several species in the right display case, at the bottom right. They are of brown and white colours and of porcelain appearance. The last largest whorl runs over all the others. When a cowry is still alive, this beautiful shell is covered by a mantle full of warty, finger-like and thorny protuberances. This mantle secretes porcelain-like substance. Cowries have been always much sought-after by collectors, and once upon a time they were even used as money. In the Adriatic Sea, four cowry species can be found.
Left from the cowries, there are shells of gastropods equipped with mother-ofpearl. These are Haliotidae, commonly known as abalone shells or sea ears. They are easily recognised, for they indeed remind us of human ears. They live attached to rocks and exchange water through the small holes on the inwardly curved side of the shell. Their flesh apparently has a very pleasant flavour. In Japan, a species occurs that can grow so big that a single specimen can suffice as a meal for a whole family. But owing to their popularity and overgathering, many abalone shell species are threatened to become extinct. In the Adriatic Sea, a sea ear representative can be found as well, called Peter's ear or ear of St. Peter. This, however, is a small gastropod, living in the rocky coastal zone. It occurs only individually and plays no major role in human diet.