1. MOLLUSKS

2. Defining Characteristics of Mollusk
Soft-bodies animals
Internal or external shell
Ex: snails, slugs, clams, squids, & octopi

3. Diversity Very diverse, but similar developmental stages
Trochophore: free-swimming larval stage
A: cillia
B: mouth
C: anus

4. Form and Function Body Plan:
Foot: flat structure for crawling
Mantle: thin tissue layer covering body
Shell: made by glands
Visceral mass: internal organs
Feeding: herbivores, carnivores, filter feeders, detritivores, or parasite
Radula: flexible tongue-like structure with 100’s teeth

5. Form and Function Circulation Respiration: gills or with mantle cavity
Open: blood pumped through vessels with a simple heart
Closed: transports blood quicker
Respiration: gills or with mantle cavity
Excretion: nephridia remove ammonia
Response to stimuli: large variance
Movement: jet propulsion & secrete mucus along base of foot

6. Groups of Mollusks
Gastropods: shell-less or single shelled, move by muscular foot
snails, slugs, sea butterflies
Bivalves: two shells held together by powerful muscles
Clams, oysters, mussels, & scallops

7. Groups of Mollusks Cephalopods: soft-bodied
Head: attached to a single foot
Foot: divided into tentacles or arms
Octopi, Squids