1. Mollusks
Chapter 10 Section 1

2. Characteristics of Mollusks
Clams, oysters, scallops, snails, squids
Invertebrates with soft, unsegmented bodies
Often protected by hard outer shell (protects soft body)
Mantle: thin layer of tissue that covers internal organ, produces the hard shell
Foot: adapted for crawling, digging, catching prey
Characteristics of Mollusks

3. Mollusk: Body Structure
Bilateral symmetry
Digestive system, 2 openings
Internal organs located in one area
Mollusk: Body Structure

4. Body Structures

5. Mollusks: Circulatory System
Open circulatory system
Blood is not inside blood vessels
Blood sloshes over the organs and returns eventually to the heart
Mollusks: Circulatory System

6. Mollusks: Obtaining Oxygen
Mollusks that live in water have gills
Gills: organs that remove oxygen from the water
Cilia: tiny, hairlike structures that move water over the gills
Mollusks: Obtaining Oxygen

7. Three Major Groups of Mollusks
GASTROPODS
BIVALVES
CEPHALOPODS
Classified by… presence of shell, type of shell, type of foot, complexity of nervous system
Three Major Groups of Mollusks

8. Snails and slugs
Largest group of mollusks
Live everywhere on Earth
Single external shell or no shell at all
GASTROPODS

9. GASTROPODS: Obtaining Food
Herbivores
Eat only plants
Carnivores
Animals that eat only other animals
Scavengers
Radula: a flexible ribbon of tiny teeth that scrapes food from a surface
GASTROPODS: Obtaining Food

10. BIVALVES Oysters, clams, scallops, mussels
Mollusks that have two shells held together by hinges and strong muscles
NO RADULAS, strain tiny organisms from water with the use of their gills
Omnivores: eat both plants and animals
BIVALVES

11. Oysters and mussels attach themselves to rocks or underwater surfaces
Clams can burrow the mud by changing the shape of its foot
Grain of sand gets stuck between mantle and shell… PEARL!
BIVALVES (cont.)

12. CEPHALOPODS Octopus, squids, nautilus, cuttlefish
Ocean dwelling mollusk whose foot is adapted to form tentacles around its mouth
Carnivores
Use tentacles containing sensitive suckers to capture food
Suckers receive sensations of taste as well as touch
Don’t have to touch something to taste it
CEPHALOPODS

13. CEPHALOPODS (cont.) Large eyes Excellent vision
Most complex nervous system of any invertebrate
Large brains, can remember things they have learned
Jet propulsion
CEPHALOPODS (cont.)

14. An Escaping Octopus