PHYLUM MOLLUSCA

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PHYLUM MOLLUSCA
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WHAT IS A MOLLUSK? Why are animals that look and
act so different grouped in the same phylum? It
is because they share developmental patterns.
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Characteristics of Mollusk 1. mantle 2. mantle
cavity 3. shell 4. true coelom 5. head,
muscular foot, visceral cavity 6. systems
circulatory, respiratory, digestive,
excretory, reproductive, and nerve
impulses
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Mollusks are well defined as soft bodied animals
that either have an external or internal
shell. Their name comes from the Latin word
molluscus meaning soft.
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Most mollusks are composed of 4 basic parts

• foot - flat surface adapted for locomotion and
  usually contains the mouth and other feeding
  structures
• mantle - covers most of the body and secretes the
  shell
• shell - composed of calcium carbonate
• visceral mass - contains the internal organ

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Unique features of most mollusks include

• Mantle
• ctenidia - special gill which are also used for
  filter feeding
• radula - rasping tongue-like structure used for
  scraping

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INTERNAL TRANSPORT
OPEN CIRCULATORY SYSTEM

• the blood is not always contained in vessels.
• there are no veins.

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What is a closed circulatory system?
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Excretion - All animals must remove waste
products. An open circulatory system will work
well for slow moving animals. Why is an open
circulatory system not adequate for fast-moving
animal