FISH STUDY
BL - 06
MATERIALS:
•A set of shape cards for each pair of students.
•Laminated photos of fish/use with shape cards
•Plastic cut-away model of a fish showing external body parts and internal organs
•Feeding levels (niche poster) with Velcro attachments/laminated colored fish
photos with Velcro backing
•Salmon head (optional) — for gills, tongue, teeth, nostril and eyes (you supply)
•Various preserved specimens found in the bay, whole and skeletons
•Photos in these books:
Robins, Richard C.
American Nature Guides – Saltwater Fish, Smithmark Pub., N.Y. 1992
Parker, Stevens
Fish – An Eyewitness Book, A.A. Knopf, 1990
•Clean-up equipment (only if using fresh fish head):
-Container of water, sponge, paper towels, Baby Wipes, fresh lemons (you
supply)
FISH STUDY
BL-06
page 1
FISH STUDY
BL - 06
SOURCE:
Mary Asazawa
Fall 1993
OBJECTIVES:
•Learning to work with partner(s)
•Identify fish by its shape
•Understanding the influence of shape on behavior and niche adaptation
SCIENCE THEMES:
Scale and structure, systems and interactions
PROCESS SKILLS:
Observing, comparing , categorizing, relating, applying
GRADE LEVELS:
K—2
FOCUS WORDS:
Oxygen
Caudal fin
Streamlined
Reproduction
Scales
Pelvic fin
Predator
Tapered
Brood pouch
Gastrointestinal
Pectoral fin
Swim bladder
Elongated
Friction
Gill raker
Dorsal fin
Fertilize
Protective
Parasites
Suffocate
Anal fin
Hydrodynamic
Camouflage
Operculum
Oxygen
BACKGROUND INFORMATION:
A fish that is long compared to its girth, and pointed on both ends is capable of swimming fast.
Most pelagic fishes (travelers of the mid-oceans) such as tuna, have this shape. They are always
traveling, and need fast spurts of speed to capture prey. Schooling fish often have this shape. They also
need spurts of speed to avoid being captured.
FISH STUDY
BL-06
page 2
BACKGROUND INFORMATION: (continued)
Fish such as salmon that travel up raging rivers to spawn must be fast enough to jump waterfalls.
This is a streamlined shape, and does not use the fishes' energy by causing turbulence. These fish may
live at any depth, and may change depths to be where the food is.
The streamlined shape, the laterally compressed (deep body but flat sides) is the shape of the
surfperch. The streamlined herring, anchovies, sardines, and other plankton eaters form schools on the
surface where the photosynthesis of the sunlight causes the plankton to thrive. These fish are usually
dark colored on the back so the seabirds can't see them readily against the darkness of the depth. They
are silvery or white on the underside so the predator fish below them can't see them readily against the
brightness of the sky.
The flyingfish has the same dark above and light below coloration but it also escapes predators by
flight. It is streamlined, and a very fast swimmer. It also has large broad pectoral fins that actually act
like wings. The flyingfish is more like a glider than a bird. This fish leaves the water on the crest of a
wave at very high speed. It then glides on its enlarged wing-like pectoral fins as far as it can until it
gets back near the surface. Then, without reentering the water it propels itself again up to flying speed
with the elongated lower lobe of its tail, like a propeller pushes a boat, as it touches the water.
Many fish have shape and color patterns to camouflage themselves. The seahorse and the pipefish
are two examples of this shape. These fishes remain motionless in the seaweed and look so much like
the seaweed that it is difficult for the predator to find them. Papa sea horse and papa pipefish do all
the raising of the children. The female deposits eggs in a kangaroo-like pouch in the male's stomach,
where the eggs become fertilized. They hatch while still in this brood pouch.
The rockfish (erroneously called rock cod and red snapper) approximates streamline, but is husky
for its length. It relies on stalking its prey and then, with a short sudden lunge, captures it. It is often
brightly colored, even though in the depths of its habitat there is often little or no light to show off its
color. These fishes are protected by spiny rays on the dorsal and anal fins and often sharp points on
their heads.
Some fish can change their shape when frightened. When a predator is near a balloonfish or a
porcupinefish it inflates itself with water to become a spherical shape, much bigger than normal. These
fish also have spines, like the quills of a porcupine. When they are inflated they resemble a beach ball
with a tail and long hard points sticking straight out all over it. Few predators would take a mouthful
of those needles.
On the bottom of the bays and open ocean live the flat fish. There are many species of flat fish, from
a 700-pound specimen of a halibut to the tiniest sanddab. These fish are somewhat diamond shaped,
although they could be oval shaped, as in the case of the tonguefish. The flatfish starts life with a
normal fish shape, eyes where they belong and a straight mouth. Shortly after birth things start to
happen; one eye starts to migrate to the other side of its head until both eyes are on the same side. The
mouth of some flat fish stay in the birth position, but on some the mouth becomes twisted. They are a
dark or sandy color on top as camouflage when they lay on the bottom with both eyes looking up.
Sometimes they cover themselves with sand waiting for a hapless fish to swim too close.
Another group of flattened fish are the skates and rays; they belong to the same family as the
sharks. Most of these fish could be considered kite shaped. Their shape comes from their large pectoral
fins that join their ventral fins and are referred to as "wings." They have a long, whip like tail often
without fins. They use their wings to move through the water much like a gull flies through the air.
FISH STUDY
BL-06
page 3
Nearly all of these fish are bottom dwellers. Two exceptions to this are the manta and the mobula
which are pelagic and filter feeders. These rays are very large; the manta can weigh as much as 2,300
pounds.
There is a group of fishes that feels safer out of the water than in it. The mudsucker of the
Indopacific is one example. It actually climbs out of the water on mangrove or other tree roots that
grow into the water. It climbs the roots by pulling itself along with its pectoral fins. If danger comes
from above, it returns to the water with one quick flip.
BACKGROUND INFORMATION: (continued)
The wrasse is a small fish and would be a tasty morsel for bigger predators, but this fish makes
friends with them by cleaning them of parasites. It swims around, over and under these larger fish
picking off the parasites without fear of being eaten. The wrasse even cleans the inside of the
predators’ mouths.
The surgeonfish has a scalpel-like spine on either side of its tail. When flaying this tail around it
can inflict serious incisions on other fish.
ACTIVITIES:
TIME:
Introduction to "What Is A Fish?" – 5 Minutes
Matching Shapes – 10 Minutes
Summary – 5 Minutes
NOTE: Optional using fresh fish salmon head with kindergarten, first or second graders. Some of
this material may be too involved for some young children. Use your discretion in what to present.
The main focus of this activity are what is a fish, how do fish shapes help us know where they are
found in the water and improve their chances for survival.
SAY: We will now try to determine what a fish is. We have some fish preserved in liquid
and we have some dried skeletons of fish.
ASK: What do all fish share that is the same?
RESPONSE: They all have eyes.
They all have a mouth.
They all have fins.
They all have a tail.
They all have gills.
They all have scales. (NOTE: If you have a catfish point out that this fish and some
other fish do not have scales.)
They are all slimy.
(Allow as many similarities as the students can find. Add a few of your own if you
can.)
DO: Give time for responses.
ASK: What are the differences?
RESPONSE: Allow as many differences as the students can find. They may be "This fish has both
eyes on the same side."
"This fish is long and skinny."
"This fish is kind of round." (Could be a surfperch.)
ASK: Is a shark a fish?
DO: Show the preserved shark specimen
FISH STUDY
BL-06
page 4
EXPLAIN:
A shark is a fish. It has most of the features that are common to all fish. But it does not
have bones.
ASK: Do all sharks look alike?
EXPLAIN: There are many different species of sharks. Many of them have the typical shark shape,
but some sharks look quite different. See North American Fish book for some photos of
sharks and other fish.
For Your Information:
•The angel shark is flat with large pectoral fins which resemble wings.
•One shark is called the guitar fish because his body resembles a guitar.
•The hammerhead has eyes spread far apart on a head that resembles a hammer.
•The thrasher shark looks like the typical shark except the top half (lobe) of its tail is as
long as its entire body.
ASK:
EXPLAIN:
Are all sharks dangerous?
Only a few of the larger sharks are dangerous. But the largest of all sharks, the Whale
shark, will not harm anything larger than the smallest of shrimp.
DO: If you use the fresh salmon head, you can use it to show the following external features,
or use the plastic relief model of the fish.
ASK: Why does a fish die when taken out of water?
EXPLAIN: As soon as a fish is taken out of the water the gills can no longer gather enough oxygen,
and the fish suffocates. Explain suffocation.
DO: Point out the scales and the operculum on the fresh fish head, or plastic model, also the
dried scales.
ASK: How can you tell the age of fish?
EXPLAIN: By counting the rings on its scale, just like tree rings.
Some fish do not have scales, so this method will not work.
ASK: How do scales help the fish survive?
EXPLAIN: Scales are small boney plates that attach to a fish like shingles on your roof. They
protect the fish from bumps and scratches. They also reduce the friction as the fish
swims through the water.
ASK: What are fins?
EXPLAIN: Some fish have more fins than others. The fins of different fish might be placed
differently from those on other kinds of fish.
The caudal fin is the tail fin; it is used for swimming.
The dorsal fin is the fin on the back of the fish, and the anal fin is underneath the belly
of the fish near the tail. These fins are used to keep the fish from turning over.
The pectoral fins are used for steering.
DO: Point to the fins as you discuss them.
ASK: Why do fish go to school? They don't really, but they do hang together in large groups
called schools.
EXPLAIN: Fish school (hang out together) for various reasons. Usually they school for breeding
and/or protection. When a predator fish sees a single fish, he can just gobble it up. But
when he sees a dense school, he cannot fix on a single fish, so he gets none.
DO: Show a photo of schooling fish.
Optional: (Skip this if the kids are getting too restless, or time is short and do the shape activity)
ASK: Do fish sleep?
FISH STUDY
BL-06
page 5
EXPLAIN:
Some do. If they can find a safe place in the rocks or some other protection they can
rest, and even sleep. They sleep with their eyes open because they have no eyelids.
ASK: How do fish use their swim bladders?
DO: Show the internal organs and the swim bladder is on the plastic relief model of a fish.
EXPLAIN: The fish has a little balloon in its stomach. He can blow it up more, or let some air out.
The fish must make himself a very little bigger or smaller by how much he blows up
that balloon. When he is the right size he can rest at whatever depth he is in without
either floating up or sinking down.
ASK: Do fish see color?
EXPLAIN: Boney fish do, but sharks do not.
Directions:
Divide students into pairs (or 3 if necessary).
Give each team a set of shape cards and one colored photo of a fish
They will match the fish photo to one of the shape cards
DO: Use a whole preserved fish and the laminated photos to show these different shapes.
Each team will match their photo to a specific shape card. Have them use the shape
cards to match each body shape you discuss below.
ASK: Which shape is streamlined for fast swimming?
RESPONSE: Allow enough time for responses about the shapes explained below.
EXPLAIN:
Tapered ends and slim, elongated body.
DO: Have each team choose the shape card for a streamlined fish.
ASK: Which shape slows swimming?
EXPLAIN: Kite shape of batray
Diamond shape of sole
DO: Have each team find the shape card that matches the ray and the sole.
ASK: Which shape is protective?
EXPLAIN: Spherical - - -Balloonfish (puffed up)
DO: Have each team find the shape card for the inflated balloonfish
ASK: How does shape determine the location of eyes and mouth?
EXPLAIN: Flat fish have eyes on top of body such as batray and halibut. Predators have eyes near
the front of their head to allow them to see their prey. Forage fish have eyes on the
sides of their head to watch for predators in all directions at the same time.
ASK: How can shape be used as camouflage?
EXPLAIN: Bay pipefish.
DO: Have each student find the shape card for the pipefish.
EXPLAIN:
Use the hand painted niche poster and the laminated photos with the Velcro backs
to stick up some of the kinds of fish eaters, or have the children help put them on the
poster. They can also decide the fish's shape. Or, you can have the poster set up
ahead of time.
Different fish eat different things:
-Scavengers (garbage eaters) eat anything they can find. They live on the bottom.
-Predators (meat eaters) catch live food. Some catch swimming fish, some feed on crabs,
worms, or clams. They are found at all levels of the water.
-Filter feeders (vegetable eaters) eat plankton. They take water in their mouths and spit
it out through their gill rakers. These fish are usually live on the surface because the
FISH STUDY
BL-06
page 6
plankton they eat needs sunlight to grow.
-Grazers nibble on coral, sponge or algae. They are found in the middle.
How does shape help a fish get what it likes to eat? If you were a fish, what shape
would you want to be and why?
ASK:
RESOURCES:
Robins, Richard C.
American Nature Guides – Saltwater Fish, Smithmark Pub., N.Y. 1992
Parker, Stevens
Fish – An Eyewitness Book, A.A. Knopf, 1990
Wilson, Josleen
North American Fish, National Audubon Society, 1991
FISH STUDY
BL-06
page 7