1. MOLLUSCSMOLLUSCS

2. MOLLUSCSMOLLUSCS -

3. Molluscs Origin of the word mollusc: From the Latin word Mollis meaning soft Animals in this phylum include: Snails, Octopus, Squid, clams, Level of organization: Organ Symmetry: Bilateral Coelomate (inner body cavity coated by mesoderm)

4. General mollusc body plan

5. Characteristics of molluscs 1)Visceral mass: Soft body containing vital organs: -intestines -kidneys -nerve ganglia 2) Foot: strong, muscular organ used for locomotion 3) Mantle: Membrane or muscle that envelopes the visceral mass. Some secrete exoskeletons

6. Exoskeleton Exoskeleton: A hard structure secreted by the mantle. Function of exoskeleton: 1)Protection (clam) 2)Structural (squid) 3)Preventing waterloss (snails)

7. Three Major Classes of Mollusc 1)Gastropods : Gastro = stomach Pod = foot Stomach foots Common examples: abalone, nudibranchs, slugs and snails

8. Gastropod Characteristics: 1) Foot flattened ventrally 2) Move via muscle contractions in the foot 3) Have one valve (shell) or no valves 4) Breath via the capillary network in the mantle Gastropod reproduction: -Hermaphrodites but not capable of asexual reproduction

9. Three Major Classes of Mollusc 2) Cephalopoda: Cephal = head poda = foot head foot Common examples: Squid, cuttlefish, nautilus and octopus

10. Cephalopods Characteristics: 1) Tentacles used to capture prey 2) Sharp beak used to dismantle prey 3)

11. Cephalopods Characteristics: 1) Tentacles used to capture prey 2) Sharp beak used to dismantle prey 3) Radula (wrasping tonge) 4) Cephalization 5)Eyes: Contain lens and retina with photoreceptors. NOT RELATED TO EYES IN OTHER PHYLA

12. Cephalopods Characteristics: 1) Tentacles used to capture prey 2) Sharp beak used to dismantle prey 3) Radula (wrasping tonge) 4) Cephalization 5) Eyes: Contain lens and retina with photoreceptors. NOT RELATED TO EYES IN OTHER PHYLA 6) Brain consisting of fused ganglia 7) Move via jet propulsion

13. Three Classes of Molluscs 3) Bivalve: Valve = shell, Bi = in two pieces Common examples: Clams, Scallops, and Mussels

14. Bivalves Characteristics: 1)Shell made from two parts secreted by the mantle 2)Shell made from protein or calcium carbonate 3)Sessile filter feeder

15. Bivalve Anatomy

16. Function of Parts PartsFunction Footmovement, digging Gillgas exchange, catches particles and uses its cilia to move it to the mouth Adductor muscleKeep the shell closed StomachDigests food

17. Circulatory System Open Circulatory system: -Heart pumps water through the whole body cavity. No tubes carrying blood. -Less efficient then a closed circulatory system.

18. Nervous System -Contains three ganglia connected by nerves -Note: No cephalization in bivalves = no concentration of nerves in one area Digestive System - Consist of: esophagus, Stomach, intestine, labial palps, anus - Excretory system contains two kidneys

19. Assignment Vocab 635-638 Summary Table Check on Planaria