1. Section 3: Mollusks
Mollusks are coelomates with a muscular foot, a mantle, and a digestive tract with two openings. K
What I Know W
What I Want to Find Out L
What I Learned

2. Essential Questions What is the importance of the coelom to mollusks?
What is the function of the mantle and what are its adaptive advantages to mollusks?
What is the importance of mucus and the muscular foot to mollusks?
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Mollusks

3. Vocabulary Review New herbivore mantle radula gill
open circulatory system
closed circulatory system
nephridium
siphon
Mollusks
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4. Body Structure
Part of phylum Mollusca, include slugs, snails, scallops, and squid.
May be the first coelomates
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Mollusks

5. Body Structure
Have bilateral symmetry, a soft internal body, a digestive tract with two openings, a muscular foot, and a mantle – a membrane that surrounds the internal organs
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Mollusks

6. Body Structure Feeding and digestion
Many mollusks use a radula, a tonguelike organ with rows of teeth, to scrape food into their mouths.
Other mollusks, such as clams, filter feed and do not have radulas.
Have a complete gut with digestive glands, stomach, and intestines
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Mollusks

7. Body Structure Respiration
Most mollusks have gills, respiratory structures that consist of filamentous projections with lots of surface area for gas exchange.
Land snails and slugs remove oxygen from the air using the lining of their mantle cavities.
Gills also function in filter feeding.
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Mollusks

8. Body Structure Circulation
Most mollusks have an open circulatory system, where blood is pumped out of vessels into open spaces surrounding the body organs.
Some mollusks have a closed circulatory system, where blood is confined to vessels as it moves through the body.
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Mollusks

9. Body Structure Excretion
Mollusks get rid of metabolic wastes from cellular processes through structures called nephridia.
After nephridia filter the blood, waste is passed out through the mantle cavity.
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Mollusks

10. Body Structure Response to stimuli
Mollusks have a nervous system that coordinates movement and behavior.
More highly evolved mollusks, such as octopuses, have brains.
Most mollusks have simple eyes.
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Mollusks

11. Add link to animation from page 740 (Figure 17) here.
Visualizing Movement in Mollusks
Animation
FPO
Add link to animation from page 740 (Figure 17) here.
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Mollusks

12. Body Structure Movement
Mollusks with two shells can clap their shells together for rapid bursts of swimming.
Snails and slugs move along a trail of mucus produced by their muscular foot.
Octopuses and squids take water into the mantle cavity and expel it through a tube called a siphon.
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Mollusks

13. Body Structure Reproduction Mollusks reproduce sexually.
All mollusks share similar developmental patterns.
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Mollusks

14. Diversity of Mollusks Gastropods
Gastropoda, or stomach-footed, is the largest class of mollusks.
Most species of gastropods have a single shell, such as snails and limpets.
Other gastropods have no shell, such as slugs and nudibranchs.
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Mollusks

15. Diversity of Mollusks Bivalves
Bivalves are two-shelled mollusks, such as clams and oysters.
All aquatic, most marine
Filter-feeders
Burrow or attach to hard surfaces such as rocks
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Mollusks

16. Diversity of Mollusks Cephalopods
Cephalopods are the head-footed mollusks, such as octopuses and squid.
Most cephalopods have an internal shell, with the exception of the chambered nautilus.
The cephalopod foot is divided into arms and tentacles with suckers.
Octopuses are considered to be the most intelligent mollusk, are capable of complex learning
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Mollusks

17. Ecology of Mollusks
Important to marine and terrestrial food webs as predators, herbivores, scavengers, and filter feeders
Can be keystone species, a species who’s health influences the health of the entire ecosystem
Filter feeders are important for cleaning aquatic ecosystems
Filter feeders can also serve as environmental monitors as they accumulate toxins in their tissues
Some snails produce toxins with pharmaceutical promise
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Mollusks

18. Review Essential Questions Vocabulary
What is the importance of the coelom to mollusks?
What is the function of the mantle and what are its adaptive advantages to mollusks?
What is the importance of mucus and the muscular foot to mollusks?
Vocabulary
mantle
radula
gill
open circulatory system
closed circulatory system
nephridium
siphon
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Mollusks