What the Bay HINGES on!
Observations, on the half Shell
Subject Areas: Science
Setting: Classroom
Duration: One Classroom Period
Skills: Research, critical thinking, observation, writing, public speaking
Vocabulary: Adaptation, shell, oyster, hard clam, quahog, scallop, mussel, whelk,
bivalve, gastropod, hinge, taxonomy, classify, dichotomous key, scientific name,
common name, organism, little neck, cherrystone, top neck, chowder, seed
Correlation to Core Curriculum Standards:
Science: 5.1 (A,B), 5.2 (A), 5.3 (A,C,D), 5.10 (A,B);
Language Arts: 3.1(G,H), 3.2 (A,B,C,D), 3.3 (A,B,C,D), 3.4 (A), 3.5 (A,B,C);
Life Skills: 9.2 (A)
Arts: 1.2 (D)
Objectives:
1. Observe and identify differences among shells
2. Understand adaptation and the advantage of shells
3. Understand the importance of shellfish to humans
4. Analyze specimens and create dichotomous keys
Materials: Edible Shell Board, pencil and paper or student journal, optional: hand lens,
From Seed to Market Board
Background:
Most shellfish are bivalves, mollusks that have two shells connected by a hinge. These
shells protect their soft bodies from damage, and are left behind when the organisms
die. Looking at shells we see on the beach can tell us what shellfish live in the nearby
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What the Bay HINGES on!
water. This activity uses visual aides to show students the many kinds of edible
shellfish, and point out differences between organisms and their shells, including the
adaptations used by different shellfish.
Procedure:
Show students the Edible Shellfish Board. Allow students to look at and touch the
various kinds of shells on the board. Ask them to carefully look at the differences
between different types of shell, stressing that size and color may not be the best judge
of difference, as they can change more than texture, number of openings, or overall
shape. Point out the parts of the different shells for the students.
Ask the students which of the edible shellfish they have ever tried. Have them make a
list of all of the different ways they’ve heard of eating shellfish. Discuss how useful the
shell can be to humans for cooking and eating, once we open it up. Have students think
of other things that humans use shell for (driveways/roads, arts and crafts, etc).
Procedure: Activity - Short Term/Younger Grades
Have the students write down and draw their observations about each shell. They
should be taking objective, notes based on what they see and touch. Describe the hinge
and valves of a bivalve, and the spiral of a gastropod. Have them describe how the
parts they learned are different on the different shells. Have them guess how the
differences in shell affect the organisms inside.
If this lesson will be used in a language arts setting, have students also look at the
shells and write descriptively about them, rather than scientifically. Have them use
metaphor to describe what the shell looks and feels like, or write a poem about the
shells.
Discuss adaptation – how characteristics can help organisms survive. Discuss the
advantages of being a gastropod versus being a bivalve. How does each type of shell
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What the Bay HINGES on!
protect its inhabitant? Why do shellfish have shells, unlike squid (another mollusk) –
why don't squid need shells to protect them (they are mobile, and have other defenses).
Have students draw the different shells and label their characteristic differences in a
journal. Have them summarize how the adaptation of a shell is useful.
Procedure: Activity - In-Depth/Older Grades
In addition to the above, examine a hard clam or surf clam shell. The ridges present on
these shells are markers of how the clams have grown over time. By examining them,
we get a general idea of how long a clam has lived, similar to the rings in a tree. Have
students study the ridges on different shells to determine how old they are. Rather than
try to find a definite age, discuss older versus younger, and slow versus fast growth,
based on the thickness of each individual band. Use the From Seed to Market Board to
illustrate the range of growth for hard clams. Note that we have different
“classifications” for different sized clams as a seafood product.
Growth rings of a hard clam. B shows a cross section of the clam above. Excerpted from Rice, 1994.
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What the Bay HINGES on!
If in the field, collect shells and other “clues” to who lives and visits the area. Discuss
with students. Make a Shell Board for the class to keep by gluing down and labeling
each different kind of shell you find. Try to find whole specimens in good physical
condition.
Extension: Taking it further
Have the students use the shells to write a short dichotomous key, using observations
they make about the shells different morphology. A dichotomous key uses a series of
paired statements to systematically identify organisms (see example below). After
identifying all of the organisms, group them by shared characteristics, for instance, all of
the organisms have shells, many of them have two shells joined by a hinges, etc.
Have the students research the biology and classification of the organisms on the
board, to see how close their classification was to scientific classes and orders (i.e. did
they separate the whelk from the bivalves?) See “Classification is the KEY” for more
information. Are there any managed shellfish in NJ that are missing from the board?
(Soft Shelled Clam, Ocean Quahog). Have them learn about these species as well.
Assessment:
Assess student journal entries
Test on shell differences
Crossword puzzle completion
Assess dichotomous keys
Class Participation
Also see:
Secret Word Puzzle, Shellgo from Beneath the Shell, NJDEP.
Seashell homes from Discovering Barnegat Bay
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What the Bay HINGES on!
Observations on the Half Shell Crossword Puzzle
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What the Bay HINGES on!
Observations on the Half Shell Clues
Across
1.
A feature of an organism that helps it to survive
4.
Word describing a shelled animal that lives in water, especially if edible
6.
A type of shellfish that has two joined shells is a ____.
8.
A whelk, like a snail, is a ______.
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This whelk is the state shell of NJ
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Shellfish known by its wavy shell
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Perhaps the biggest predators of shellfish, harvest in large numbers
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The point at which a bivalve shell opens and closes
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Another name for the Hard clam, from "poquauhock" in Native American
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The powerful muscles that keep bivalve shells closed
Down
2.
A key that lists characteristics in paired statements.
3.
This famous local crab eats shellfish, as well as being an important food source itself
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The most important commercial shellfish species in Barnegat Bay (has a space)
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The science of classifying things.
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Often, oysters build up over time and form this kind of structure.
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This shellfish likes to settle on hard surface, often growing on its own kind.
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Another name for the Whelk
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What the Bay HINGES on!
Observations on the Half Shell Crossword Key
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A D A P T A T
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G A S T R O P O D
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Q U A H O G
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A D D U C T O R
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