Transcript Chapter 15 Section 2 Mollusks and Annelid Worms

Chapter 15
Section 2 Mollusks and Annelid Worms
Bellringer
Unscramble the following words and write a
sentence that uses all of the words.
• gluss
• isalns
• sdusqi
• klomssul
Write your sentence in your science journal.
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Chapter 15
Section 2 Mollusks and Annelid Worms
Objectives
• Explain how mollusks eat, control body functions, and
circulate blood.
• Describe the four body parts that most mollusks have
in common.
• Describe the three kinds of annelid worms.
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Chapter 15
Section 2 Mollusks and Annelid Worms
Mollusks
•Most mollusks fit into three classes:
• The gastropods include slugs and snails.
• eat with radula, a toungelike organ
covered in teeth
• The bivalves include clams and other
shellfish with two shells.
• use gills to filter tiny plants, bacteria,
and other particles from the water.
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Chapter 15
Section 2 Mollusks and Annelid Worms
Mollusks, continued
•The cephalopods include squids and
octopuses.
• grab food with tentacles and place it
in their powerful jaws
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Chapter 15
Section 2 Mollusks and Annelid Worms
Mollusks, continued
• Ganglia and Brains All mollusks have
complex ganglia.
•control breathing, movement, and
digestion.
• Cephalopods, such as octopuses, have large
brains that connect all of their ganglia.
• Most advanced nervous system of all
invertebrates..
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Chapter 15
Section 2 Mollusks and Annelid Worms
Mollusks, continued
• Pumping Blood
• open circulatory system, a simple heart
pumps blood through blood vessels that
empty into sinuses, or spaces in the
animal’s body.
• Most mollusks have an open
circulatory system.
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Mollusks Pumping Blood , continued
• closed circulatory system, a heart pumps
blood through a network of blood vessels that
form a closed loop.
• Squids and octopuses
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Chapter 15
Section 2 Mollusks and Annelid Worms
Mollusks, continued
• Mollusk Bodies
• Foot – muscular foot for moving
• Visceral Mass – gills, gut, and other
organs are in visceral mass
• Mantle – covers visceral mass and
produces shell
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Chapter 15
Section 2 Mollusks and Annelid Worms
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Chapter 15
Section 2 Mollusks and Annelid Worms
Annelid Worms
• bodies have segments. A segment is almost
an identical, repeating body part.
• bilateral symmetry
• closed circulatory system
• complex nervous system with a brain.
• Annelid worms live in salt water, fresh water,
or on land. They eat plant material or
animals.
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Annelid Worms
• 3 Major groups
• Earthworms
• Marine Worms
• Leeches
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Chapter 15
Section 2 Mollusks and Annelid Worms
Annelid Worms, continued
• Earthworms
• Each earthworm has 100 to 175
segments.
• Their castings, or waste, improves soil
quality.
• Tunnels allow air and water to enter soil
• use stiff hairs, or bristles, on the sides of
their bodies to move.
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Chapter 15
Section 2 Mollusks and Annelid Worms
Annelid Worms, continued
• Marine Worms
• Polychaete – many bristles
• live in the ocean.
• eat mollusks, other small animals, or filter
food from the water.
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Annelid Worms, continued
• Leeches
• Some leeches are parasites that suck
other animals’ blood.
• Other leeches eat dead animals or hunt
insects, slugs, and snails.
• Secrete a chemical to keep blood flowing
and not form clots
• Used for medical purposes
• Doctors use leeches to prevent swelling.
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