Chapter 13: Mollusks, Worms, Arthropods, Echinoderms

Mollusk Protection
If you’ve ever walked along a beach, especially
after a storm, you’ve probably seen
many seashells. They come in different colors,
shapes, and sizes. If you look closely, you
will see that some shells have many rings or
bands. In the following lab, find out what the
bands tell you about the shell and the organism
that made it.
1. Use a magnifying lens to examine a clam’s
shell.
2. Count the number of rings or bands on
the shell. Count as number one the large,
top point called the crown.
3. Compare the distances between the
bands of the shell.
4. Think Critically Do other students’
shells have the same number of bands?
Are all of the bands on your shell the
same width? What do you think the bands
represent, and why are some wider than
others? Record your answers in your
Science Journal.
Start-Up Activities
Preview this chapter’s content
and activities at
life.msscience.com
STEP 1
STEP 2
STEP 3
STEP 4
Invertebrates Make the following
Foldable to help you
organize the main characteristics
of the four groups of complex
invertebrates.
Draw a mark at the midpoint of a
sheet of paper along the side edge.
Then fold the top and bottom edges
in to touch the midpoint.
Fold in half from
side to side.
Turn the paper
vertically. Open and
cut along the inside
fold lines to form
four tabs.
Label the tabs
Mollusks, Worms,
Arthropods, and
Echinoderms.
Classify As you read the chapter, list the characteristics
of the four groups of invertebrates under
the appropriate tab.
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