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GENERAL CHARACTERISTICS
• Lifestyle- Variety, bottom feeders, borers, burrowers,
parasites, predators
• Economics- food, pearls, gardeners, hosts, sewers, predators, cleaning
• Bilateral symmetry
• Unsegmented, but has a definite head(cephalization)
• Locomotion- muscular foot
• Nervous system- Nerve cords, sensory nerve endings that sense touch, smell, taste, equilibrium, vision in some, and ganglia
• Respiration- O2/CO2 exchange through body surface and gills or lungs
• Circulatory system •Open system in most•Closed system in cephalopods
• Digestion - complex and specialized in different molluscs
- True coelom - Radula a hard tongue
• Excretion- Specialized system with a pair of kidneys for osmoregulation
• Reproduction- Most are dioecious, some are hermaphroditic or monecious
Bivalvia (continued)
• Filter feeders (*no radula*)
• No cephalization
• Reproduction- dioecious with external fertilization
• Development- 3 larval stages trochophore larva spat
BivalviaShells divided into two parts. Gills are used for feeding and gas exchange.Example: Clams, oysters
Bivalvia (continued)
• Respiration- gills in mantle
• Nervous system- 3 pair of ganglia with 2 pair of nerve cords
• Sense organs- chemoreceptors statocysts in foot (balance)
Examples• Snails• Limpets• Slugs• Welks• Conchs• Sea slugs
CharacteristicsClass: Gastropoda----Large foot
Class: Gastropoda
• Largest and most diverse class of mollusca 2nd largest class overall 40,000 living species 15,000 fossils
• Most have shells
• most are bilateral/torsion causes asymmetry
Class: Gastropoda
• Mostly herbivours, some scavengers living on the dead and some carnivours
• Digestion- enzymes, extracellular and intracellular
(chemical / mechanical)• Respiration- By gills in the mantle
Terrestrial has lungs
Class: Gastropoda
• Nervous system- 3 pairs of ganglia
• Reproduction- Dioecious Monecious, but self fertilization rarely occurs
• Sense organs- Tentacles on head which may have eyes Statocysts in foot
Class: Cephalopoda
• Most complex class• *Most advanced invertebrate brain*• All are predators• All are marine• 2cm-30cm normal / Giant squid 18m• Ink production for protection
• Chromatophores pigment cells in skin controlled by nervous system and hormones allow cephalopods to change colors
Class: Cephalopoda• Locomotion-expelling water from mantle
• Reproduction- dioecious internal fertilization
• Circulatory system- Closed with capillaries to organs• Respiration- Gills
Class: Cephalopoda• Nervous system- Central with large brain Nerves with ganglia and buccal ring• Sense organs
•Eyes•Statocysts•chemoreceptors