The Molluscs
• General Features
• Protostomes
• 2nd largest phyllum, > 80,000 species
The Molluscs
• All Molluscs possess some or all of the following characteristics:
• A muscular foot
• a visceral mass
• a mantle
• a radula
• a special respiratory gill
• a shell
The Bivalves
• General
• aquatic, mostly marine
• suspension or deposit feeders
• 2 valves
• epi & infauanalBivalves
• Burrowing
• Muscular foot allows burrowing to occur
• Function of the shell - hold in place
Bivalves
• Feeding
• suspension feeding using gills
• siphons, fused mantle tissue => infaunal supension feeders
• labial palps near mouth (gather food from gills)
Bivalves
• Valve Mechanics
• closing => aductores
• elastic ligament for openingBivalves
• Life Modes
(1) infaunal burrowers
(2) epifaunal => byssaly attached, cemented, free lying
(3) swimmers => pectens
(4) borers
Bivalves
• Shell Features
• Muscle scars
• Pallial line and sinus
• Right versus left valves
• dentition