Mollusca Notes
- 1. Phylum Mollusca - From mollus meaning “soft”
- 2. Classification Kingdom- Animalia Phylum- Mollusca 4 classes:
- 3. 1. Class- Gastropoda - “stomach foot” Has one shell or none Ex. Snails, slugs, sea slugs Snail Conch Slug Whelk Abalone
- 4. 2. Class Bivalvia - “Two Shells” Ex. Clams, mussels, oysters, scallops Clam Mussel Scallop Oyster
- 5. 3. Class Cephalapoda - “head foot” No shell or one Ex. Squid, octopus, nautilus, cuttlefish Octopus Squid Nautilus
- 6. 4. Class Polyplacophora - “many plates” Mantle made of 8 dorsal plates Ex. Chitons
- 7. Characteristics Eucoelomate - True body cavity Hollow body cavity, Lined with peritonium (endodermis) Bilateral symmetry Most have Mantle Secretes shell - grows with organism Site of Respiration in terrestrial mollusks
- 8. Habitat Aquatic- Marine: Sea slugs (Nudibranchs), clams, oysters, scallops, mussles, conch, whelk, squid, octopus, cuttlefish Fresh water: Clams, mussles, snails Terrestrial - Snails, slugs
- 9. Organization Tripoblastic - 3 tissue layers Many Organ systems well-defined circulatory, respiratory, excretory, and digestive systems
- 10. Respiration Aquatic- gills Terrestrial- mantle and some with primitive lungs
- 11. Digestion Complete digestive tract mouth and anus Radula Rasping “file” with hundreds of tooth like structures Feeding Patterns - filter feeders, herbivores, carnivores
- 12. Circulation Some - Open Circulatory System Blood flow doesn’t always stay in vessels Ex. Gastropoda and bivalvia Some - Closed circulatory system Blood flow stays within the vessels Ex. Cephalopoda All have hearts
- 13. Cephalization Brain with nervous system Gastropoda and Cephalopoda Exception Bivalvia no head=no brain Sensory cells All have - Touch, smell, taste, balance Some have - True eyes Cephalopoda and some Gastropoda
- 14. Locomotion Muscles are present Some sessile (mussels and oysters) Some use foot to burrow, crawl/ drag Some use tentacles to creep Some swim Some flutter away (scallops)
- 15. Reproduction Almost all dioecious Some release sperm or eggs into water Some use internal fertilization
- 16. Ecological Roles Food for many Destruction *can destroy engines and docks Cuttlebone used for parakeet beak health Jewelry / Decoration Abalone - mother of pearl Pearls - necklaces, rings, earrings Medical research - black pearls don’t get cancer