MOLLUSCA (Molluscs)
The Mollusc Section of the WA Museum was founded in 1964 and is responsible for documenting the molluscs of the state. The collection includes marine, terrestrial and freshwater, "wet" and "dry" specimens, totalling approximately 270,000 lots.
Western Australia is one of the largest remaining areas where molluscs have not been sufficiently studied in scientific detail. Over 2000 species of molluscs are known to occur in Western Australian waters, with nearly 10% of these being endemic to our coast.
There are over 340 Holotypes in the mollusc collection of the WA Museum - a large portion of which are land snails and opisthobranchs. To aid in scientific research, over 23,000 specimen lots have so far been databased, with that number increasing every day! The opisthobranchs and camaenid & bulimulid land snails represent a significant proportion of those records databased thus far.
The emphasis of the collection is on Western Australian molluscs; with most of the marine collection ranging from the southern temperate to northern tropical (Indo-West Pacific) areas of the WA coast. The collection is mainly composed of various families of marine seashells and seaslugs, and the diverse and highly endemic land snails (particularly Camaenids and Bulimulids).
The collection also has records from various parts of the world, particularly the adjacent Indo-West Pacific regions.
Staff Members:
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Shirley Slack-Smith Interests: Bivalves; Land Snails and Scaphopods |
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Corey Whisson Interests: Micro land-snails; Freshwater & Estuarine Molluscs; Bivalves. |
What is a Mollusc?
Molluscs are typically soft-bodied, unsegemented invertebrates that possess an anterior head and a dorsal visceral mass. They are at least, partly enclosed by a fleshy layer called the mantle. In most molluscs this organ secretes a hard shell, however in some molluscs the shell has been reduced; incorporated into the body, or both. Many molluscs have a muscular ventral foot, which is primarily used for movement, and a rasp-like radula (a horny, band or ribbon that bears minute teeth on its dorsal surface) to tear up food and draw it into the mouth.
There are six different classes of Molluscs:
Bivalvia
(Clams, Oysters, Scallops, Mussels etc.)
Meaning "shell has two valves". Shell valves (halves) are dorsally hinged and formed from a large, two-lobed mantle. The shell completely encloses the body of the animal. Bivalves lack a defined head and radula. Most are filter feeders and live on minute particles of algae and detritus.
Gastropoda
(Seaslugs, Snails, Cowries etc.)
Meaning "belly-footed"., the gastropods make up the largest class in the phylum. Most gastropods have gills, and generally have a well-developed head with eyes and tentacles. When present, their singular shell is coil or cone-shaped and often sealed by a "trapdoor" called an operculum. Gastropods can be marine, freshwater or terrestrial.
Cephalopoda
(Squid, Cuttlefish, Octopus etc.)
Cephalopods have a well-developed head with complex eyes. They have a cluster of arms and/or tentacles that form a ring around mouth. They have a funnel that is derived from the foot, in fact, their name means "head-footed". The sexes of cephalopod species are separate.
Polyplacophora (Chitons)
Meaning "bearer of plates". Chitons possess eight separate plates that overlap to form a shell. Their bodies are generally oval-shaped; flattened back to front. The head lacks eyes and tentacles. A toothed radula is present. Chitons feed on algae and tiny organisms. All are marine; rock dwelling and found in shallow waters.
Scaphopoda (Tooth or Tusk Shells)
Scaphopods possess a slightly-curved, tapering, tusk-like shell that is open at both ends. The larger end remains anchored in the sand by a cone-shaped (digging) foot; hence their name which means: "spade-footed". Their mantle is a tubular (tooth-like) shape and they lack gills. All the members of this class are marine.
Aplacophora
Meaning "bearers of no shells". These molluscs are worm-like in appearance and belong to the smallest (and least-researched) class in the phylum. Their shells have been replaced by calcareous spicules (small rods). Many lack gills and a radula. All aplacophorans are marine.