Showcase with the hexacoralls
The first showcases contain unicellulates represented mostly by pictures and moulds. Examples of deep-water “giant” foraminifers are shown, as well.
Among sponges displayed, of special interest are a Hexactinellid sponge, the Venus's Flower Basket, and a Cornacuspongid sponge, the Neptune's cup.
Coelenterates are represented quite broadly, with skeletons of reef-building stony corals of most bizarre forms taking special place.
Diversity of the roundworms
Flatworms and roundworms do not look much attractive, but provide an opportunity to get acquainted with the creatures, which are usually not paid attention. Total preparations, i.e. the whole animals fixed in alcohol, are complemented by explanatory diagrams showing their complex life cycles.
Among annelids, a preparation of giant earthworm from the karst caves of France should be noted.
The snow crab (Chionoecetes opilio)
In the part of exhibition displaying crustaceans (subphylum Branchiata of the phylum Arthropoda), attention should be paid to the decapod crustaceans such as crayfish, lobster, shrimps, hermit crab, king crab, the typical crabs, fiddler crabs. Obviously, the most ancient arthropods, like crustaceans, inhabited the seas, where they are quite diverse and numerous presently.
Showcase with the bivalve mollusks
Examination of one of the most diverse groups, namely the mollusks, begins with the chitons, whose shell is a dorsal plate divided into separate transverse segments, covering each other like shingles. In some chitons, their shell is completely hidden in the body (Cryptochiton).
The inner surface of the shell in many bivalve mollusks (pearl oyster, some other oysters) is covered by a layer of shimmering (but not containing color pigments) mother-of-pearl. Note the drastic simplification of the bivalve body (exemplified by an opened scallop show no head, a strong reduction of the feet, etc.) associated with the filtering feeding mode and, respectively, with sedentary (freshwater mussels) or completely motionless (sea mussels) way of life. The Giant Tridacna is the largest bivalve mollusk.
Examination of the class of gastropods is advisable to start with Abalones (Abalone and Abalone Rainbow Drive), known for their beautiful mother-of-pearl and tasty meat. Unlike bivalves, gastropod shell is wrapped into a more or less elongated spiral (trumpeter, trochids), which is sometimes almost completely obscured by the latest heavily overgrown turnover (the cowries). In the latter case, the shell of live mollusk is covered by the mantle petals.
Completing familiarity with the mollusks is advisable by observing representatives of the class of cephalopods.
In the vast majority of cephalopods (squid, cuttlefish, octopus), the outer shell has disappeared, and its small vestige is hidden in the mantle thickness. The only cephalopod preserving the ancestral outer calcareous shell is Nautilus, while the one in Argonaut is a secondary phenomenon. Mineralized remains of shells in the extinct cephalopods, such as ammonites (ancestors of the Recent cuttlefish) and belemnites, or “bloody fingers” (ancestors of the Recent squid), suggests that all ancient cephalopods had a well-developed outer shell like most of the Recent mollusks.
Showcase with the sea
Members of the phylum of echinoderms, which are starfish, sea urchins and sea cucumbers, look very different from each other. The body of the vast majority of the sea stars is radially symmetric (Asteria, Crossaster). These animals, in spite of a very complex internal structure, are known for their superior ability for regeneration, i.e. restoration of the lost body parts.
The sea urchins typically have a rigid exoskeleton, more or less spherical in its shape, their needles (sharp not in all urchins) not only protect them from predators, but also serve for locomotion. One of the most dangerous animals in the shallow tropical seas is Cidaris (tiara), whose needles are very sharp and brittle and easily penetrate unprotected skin, where they break down and are recovered with great difficulty.
One can also note a very interesting sample of preparations of the deep sea cucumbers. Some of them live in deep trenches at depths greater than 10,000 meters.
This invertebrate exhibition is finished with a small sample of the hemichordates, that are tunicates and salps. These slow-moving creatures have certain structural features showing their relation to the chordates (fishes, amphibians, reptiles, birds and mammals).