1. PHYLUM MOLLUSCA

2. Phylum characteristics • More species of mollusca than any other group in the ocean, 110,000 living species. • Bilateral symmetry • Complete digestive tract. • Respiration may be surface exchange, gills or lungs. • Nervous system is cephalized; ganglia • Soft body protected by a calcium carbonate shell which is secreted by a mantle.

3. CLASSES Bivalve Gastropoda Cephalopoda

4. Class Bivalve • EX. Clams, oysters, mussels, scallops • 2 shells joined by a ligament • Anterior & Posterior adductor muscles • Filter feeders • Lack Radula

6. Class Gastropoda • Largest group of mollusca • Torsion • Larvae start as bilateral but because of torsion become asymmetric. • Many have an operculum • Ganglion and eyes • Dioecious or hermaphroditic. Sperm-darts

7. Who are they? (conch, abalone, murex, cowrie, cones)

8. Class Cephalopoda • ‘Head-foot’ • Most complex brain of all invertebrates. • 90+ tentacles • Beak inside buccal cavity • May have internal shell or lack shell entirely. Only 1 in this class has an exterior shell. • Chromatophores

10. SQUID Dissection