Content Outline for Teaching - Potosi School District - Home

17
Section 3
Content Outline
for Teaching
Mollusks and Segmented Worms
Invertebrate Animals
Underlined words and
phrases are to be filled
in by students on the
Note-taking Worksheet.
A. Characteristics of mollusks—invertebrates usually with shells protecting their
soft bodies, mantle, and muscular foot
1. Mantle—tissue that covers a mollusk’s soft body and that may produce a shell
2. Lungs or gills exchange carbon dioxide from the animal for oxygen in the air
or water.
3. Many mollusks use a radula,ascratchy tongue-like organ, to help them eat.
4. Some mollusks have an open circulatory system which washes blood over
organs and lacks blood vessels.
B. Types of Mollusks
1. Gastropods—most have one shell
a. Live in water or on land
b. Move by gliding their large muscular foot along a trail of mucus
2. Bivalves—have two shells
a. Large muscles open and close shell halves
b. Water animals that filter feed
c. Use gills to remove foot from water
3. Cephalopods—have no shell
a. Have a foot divided into tentacles with suckers
b. Move by using a mantle to quickly squeeze water through a funnel-like
siphon
c. Have a closed circulatory system with blood vessels
C. Segmented Worms—also called annelids,have repeating segments, a closed circulatory
system, and digest food in a complete system with two openings
1. Earthworms—have more than 100 body segments
a. Use external bristle-like setae and muscles to move
b. Eat organic material in soil
c. Exchange carbon dioxide and oxygen through mucus-covered skin
Invertebrate Animals 56