Mollusc Characteristics
- Coelom reduced
- Most viscera concentrated in dorsal visceral mass
- Body covered by thick mantle (epidermis) which forms a cavity
- Mantle secretes calcium carbonate shell (or spicules)
- Large ventral muscular foot
- Radula (band of teeth in esophagus)
- Additional classes not covered in lab:
- Aplacophora
- Monoplacophora
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Class Polyplacophora — Chitons
Characteristics
- Dorso-ventrally flattened and somewhat elongated
- 8 dorsal shell plates (valves)
- Mantle forms thick lateral girdle (and sometimes covers plates)
- Lack eyes, antennae
- Marine
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Conspicuous Chiton, Stenoplax conspicua, CA
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Lined Chiton, Tonicella lineata, CA
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Black Chiton, Katharina tunicata, CA
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Dorsal view of gumboot chiton, Crytpochiton stelleri, the world's largest species (30 cm); CA
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Ventral view of gumboot chiton; CA
See also labeled photo.
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Class Gastropoda — Snails & Slugs
Characteristics
- Coiled, asymmetric shell (lost in many)
- Visceral mass (gut, nervous system) becomes twisted 90-180°
- Muscular, flattened, creeping foot
- Head with eyes (may be reduced or lost), tentacles
- Mantle highly vascularized; becomes lung
- Marine, freshwater, and terrestrial
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Veliger (larval) stage of Slipper Limpet, Crepidula sp.; stained whole-mount.
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Shell structure of a frogsnail, Bursa sp.
See also labeled photo.
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Dissection of a Garden Snail, Helix sp.
See also labeled photo.
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Giant Keyhole Limpet, Megathura crenulata (Subclass Prosobranchia); CA
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Chestnut Cowry, Cypraea spadicea (Subclass Prosobranchia); CA
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Flamingo Tongues, Cyphoma gibbosum (Subclass Prosobranchia); Belize
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Kellet's Whelk, Kelletia kelletii (Subclass Prosobranchia); CA
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Dogwinkles, Thais lapillus (Subclass Prosobranchia); ME
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Scaled Worm Snail, Serpulorbis squamigerus (Subclass Prosobranchia); a tube-dwelling snail that captures food using sticky strands of mucus
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Yellow Porostome, Dendrodoris fulva (Subclass Opisthobranchia); CA
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Navanax, Navanax inermis; (Subclass Opisthobranchia); LaJolla, CA
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Sea Hare, Aplysia californica (Subclass Opisthobranchia); LaJolla, CA
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Hopkin's Rose, Hopkinsia rosacea (Subclass Opisthobranchia); CA
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Unidentified Blue Land Snail (Subclass Pulmonata); CA
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African Giant Snail, Achatina fulica (Subclass Pulmonata), a large (10-15 cm) terrestrial species; Kenya
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Bladder Snail, Physa sp. (Subclass Pulmonata), a small (8 mm) fresh water species.
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Banana Slug, Ariolimax columbianus (Subclass Pulmonata); note pneumostome; CA
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Unidentified slug (Subclass Pulmonata); ME
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Class Bivalvia — Clams, etc.
Characteristics
- Body and foot laterally compressed
- Shell with two hinged valves
- Reduced cephalization
- Edges of mantle usually fused to form siphons
- Radula lost
- Marine and freshwater; mostly filter-feeders
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Flat-tipped Piddocks, Penitella penita, CA
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Giant Clam, Tridacna sp.
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Left Valve of a Northern Quahog, Mercenaria mercenaria.
See also labeled photo.
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Swimming Scallop, Chlamys sp.
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California Mussels, Mytilus californianus; CA
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Class Scaphopoda — Tusk Shells
Characteristics
- Single tubular, tapered shell
- Shell open at both ends
- Anterior adhesive tentacles
- Benthic marine environments
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Tusk Shell, Dentalium sp.; shell only
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Class Cephalopoda — Squid, etc.
Characteristics
- Shell chambered (if present), reduced, or absent
- Prehensile tentacles surround mouth
- Mouth with radula and beak
- Muscular siphon provides jet propulsion
- Well developed brain, eyes
- Closed circulatory system
- Marine
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Pacific Giant Octopus, Enteroctopus dofleini (Subclass Coleoidea; Order Octopoda)
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Chambered Nautilus, Nautilus pompilius (Subclass Nautiloidea)
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Dissection of a Squid, Loligo sp.
See also labeled photo.
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Broadclub Cuttlefish, Sepia latimanus (Subclass Coleoidea; Order Sepioida)
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