1. Snails, Clams, Mussels, Squid, and Octopi
Phylum Mollusca
Snails, Clams, Mussels, Squid, and Octopi

3. Lophophore- Ciliated tentacles around a mouth
Phylum mollusca
General Characteristics:
Triploblastic; Coelomate
Bilateral Symmetry
Protostomes
Lophotrochozoan
Lophophore- Ciliated tentacles around a mouth
Trochozoan- Ciliated larva

4. General Body characteristics
Foot- Muscular and used for locomotion and protection; Contains stomach in gastropods and head in cephalopods.
Mantle- Part of the foot that secretes the shell
Shell- Present in all but slugs; secreted by the mantle; provides protection and shelter
Radula- Teeth of the mollusk; one of the hardest substances known; NOT IN BIVALVES

5. RADULA
FOOT

6. General Body characteristics
Visceral Mass: Contains internal organs
Respiratory- Lung/ Gills- Depending on whether they are aquatic or terrestrial
Circulatory- Open circulatory system with true heart
Exception is Cephalopods have a closed circulatory system.
Excretory- Kidneys
Reproductive Organs
Digestive- Stomach & Intestine
Head- All mollusks have cephalization with cerebral ganglia and eyes to organize their external environment.
Eyes- Not present in most bivalves…
Tentacles- Not in Bivalves

7. Gastropods…. Snail Heart

8. Gastropod eyes

9. bivalve eyes

10. Cephalopod eyes

11. Three Major classes of mollusca
GASTROPODA
SNAILS, SLUGS, LIMPETS, NUDIBRANCHS
BIVALVIA
MUSSELS, CLAMS
CEPHALOPODA
OCTOPI, SQUID, CUTTLEFISH, NAUTILUS

12. GASTROPODA

13. GASTROPODS MARINE, FRESHWATER, AND TERRESTRIAL EXAMPLES
HERBIVORES, PARASITES, AND PREDATORS
MOVE BY SECRETING MUCOUS FROM FOOT
MONOECIOUS OR DIOECIOUS DEPENDING ON SPECIES
HAVE A LOVE DART FOR SPERM TRANSFER

14. INTERESTING….
Giant African Land Snail can weigh 2 pounds!
Land snails can lift ten times their own weight up a vertical surface
Snail blood is not contained w/in vessels; instead it washes over the body tissues

16. Snail torsion
Torsion is a process snails use to protect their visceral mass.
They can rotate body 180 degrees and retract their head first into shell. Their foot goes in last. Protects all vital organs and nerve tissue.

17. BIVALVIA

18. bivalvia MARINE AND FRESHWATER SPECIES MOSTLY FILTER FEEDERS
MOSTLY DIOECIOUS
HAVE MULTIPLE SENSORY ORGANS: STATOCYST AND CHEMORECPTORS
HAVE TWO SIPHONS FOR FILTERING FOOD PARTICLES
MUSCLES FOR OPENING AND CLOSING SHELL

19. Mussels are a great indicator of water quality. INTERESTING….
Largest bivalve is measured at 734 pounds and 4 feet long
Quahog can live to be 220 years old!
Mussels are a great
indicator of water
quality.

21. CEPHALOPODA

23. CEPHALOPODA Most intelligent invertebrates
Chromatophores- used for color change
Incorporate an ink for use in protection from predators
Siphon is used for movement and to distribute ink
Radula is modified as a beak
Dioecious
Shell is internal in squid and cuttlefish; absent in octopi
Active predators

24. Chromatophores Squid intelligence Other random stuff

25. Gills, heart = red
Caecum = yellow
Also note:
Arms
Siphon
Retractor muscle
Anus w/ “ink”
Mantle

26. Cephalopod systems
Digestive- Very high metabolic rate; Predatory and Carnivorous
Respiratory- Through gills
Circulatory- Closed circulatory system; Blood is in vessels
Nervous- Very large brain; Large advanced eyes; Chemoreceptors
Reproductive- fully developed reproductive system

27. INTERESTING…. SOME NAUTILUS SPECIES CAN LIVE 15 YEARS.
GIANT SQUID CAN GROW TO 400 POUNDS IN NATURAL HABITATS.
MOST CEPHALOPODS ONLY LIVE ABOUT 2 YEARS!
SOME SPECIES OF SQUID CAN REACH SPEEDS OF UP TO 25 MPH.
SOME OCTOPI CAN DISPLAY BIOLUMINESCENCE