Mollusks

1
Mollusks

• Read 530-535
• HW pg 535 1,2,4
• Arthropod lab due next class

2
Mollusks

• Soft-bodied
• Bilateral
• 2 opening digestive tract (sometimes coiled to
  increase length)
• Feed by filter feeding or using beaklike jaws
• Simple nervous system (except for class of
  cephalopoda)
• Open circulatory system (except for cephalopoda)

3
Mollusk anatomy

• Mantle a soft outer tissue layer that sometimes
  forms a protective shell
• Muscular foot used for locomotion or attachment
  to stationary objects
• Visceral mass a grouping of most internal
  organs heart, gonads, and stomach.

4
Mollusk reproduction

• Mostly sexual
• Can be internal or external depending on species
  and environment (aquatic vs terrestrial)

5
Major Classes

• Evolutionary Milestones protostomes
• Major classes
• Polyplacophora
• Gastropoda
• Cephalopoda
• Bivalvia

6
Polyplacophora

• Also known as Chitons
• Have 8 shell plates
• Mostly aquatic, ranging from intertidal zone to
  deep ocean.

7
Gastropoda

• Also known as snails and slugs
• Includes both aquatic and terrestrial organisms
• Can smell, see, and touch but have no hearing
• Contain both a central nervous system and
  peripheral nervous system

8
Cephalopoda

• Includes squids, octopi, nautilus, and cuttlefish
• Considered most intelligent invertebrates and
  have a large brain
• Have advanced vision

9
Bivalvia

• Have a 2 part shell
• Only aquatic
• Has a simple nervous system (and no brain)