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Presentation on theme: "PHYLUM MOLLUSCA."— Presentation transcript:


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

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