| UNIT
2Myths and Facts About This Apex Predator
These lessons and activities will teach students how important sharks
are to the marine environment, maintaining the balance of the entire marine
ecosystem. Students will understand the vital importance of sharks from
a broad, worldwide perspective and power the media has had in coloring
our perspectives of this apex predator.
Lesson 1: Create a Shark
Background Information
Sharks are an apex predator, which means they are at the very top of the
food web. They have no natural predators.
Students often assume all shark species are voracious predators with
sharp teeth, prominent dorsal fins, and large hydrodynamic bodies, but
this is far from true. There are over 375 known species of sharks swimming
the oceans today. They exhibit extreme diversity in form, behaviors, and
the habitats they occupy. They come in all sizes, from the 15 meter whale
shark to the 21 cm dwarf dogshark. They bear young in more ways than any
other group of fishes: some are viviparous (bearing live young), some
are oviparous (bearing eggs), some are ovoviviparous (hatching eggs internally
and expelling live young). There are sharks that roam the deep oceans,
sharks that prefer shallow waters, sharks that migrate across oceans,
and sharks that remain inshore. Some sharks swim constantly, some rest
quietly on the bottom. There are sharks that eat large fish, sharks that
eat crabs and urchins, and sharks that eat only plankton. Far from being
the feared deep ocean predator, sharks are unique and fascinating creatures.
This activity lets students use their imaginations to create their sharks
that can survive in given habitats. Students will learn that sharks come
in all different shapes and sizes and they have a variety of adaptations
that allow them to fit into their niche.
Objectives
Students will be able to:
think creatively and work to solve problems
discover a variety of sharks they may never have heard
of
name 3 specific adaptations sharks have to fit various
lifestyles
understand that these adaptations are inherent to a
shark’s survival
Materials
Colored pens, pencils, crayons
Paper, colored paper
Scissors
A variety of books with pictures of sharks (see suggestions below)
Shark Examples
Goblin Shark: length – 14 feet. Very rare, deep-water sharks. It
is guessed that they are fish
eaters, but little is known about them.
Cookie-cutter Shark: length – 1 ½ feet. Eats bites of large
whales, elephant seals (and other
large seals), dolphins, marlin, tuna
Megamouth Shark: length – 15 feet. Eats plankton.
Horn Shark: length – 4 feet. Eats sea urchins.
Angel Shark: length – 6 feet. Eats small fish and crustaceans.
Cigar Shark: length – 9 inches. Eats squid, small fish.
Wobbegong: length – 10 feet. Eats crabs, lobsters, octopus, small
fish.
Basking Shark: length – 48 feet. Eats plankton.
Saw Shark: length – 4 feet. Eats small fish, invertebrates and
crustaceans in the sediment
Zebra Shark: length 11 feet. Eats shellfish and small fish
Vocabulary
pelagic
habitat
apex predator
carnivore
niche
consumer
adaptation
plankton
producer
Procedure
**This activity works best if there is a wide variety of shark species
for students to choose from. Include some pelagic carnivorous sharks (tiger
shark, bull shark), large plankton feeders (whale shark, megamouth shark),
bottom dwellers (nurse shark, angel shark), small sharks (dwarf dogfish,
cigar shark). Choose sharks with unusual names and ones with which students
will hopefully not be familiar. There are over 375 species of sharks from
which to choose, so have fun! Refer to the resources and links for ideas.**
1. Discuss what organisms need to survive – food, protection, shelter,
etc. Discuss the concept of “adaptations” – that animals
have a variety of shapes, forms, and behaviors depending on what it eats,
how it protects/defends itself, and where it lives. Few creatures show
such a wide variety of adaptations as do sharks.
2. Explain that there are over 375 species of sharks. What would happen
if they all lived in the deep ocean or all ate the same type of fish?
Most of them would quickly die out. Because of this, each shark has evolved
to fit a specific type of habitat or niche.
3. Assign each student a shark, tell them only its name, maximum length,
and what it eats.
4. Using their imaginations, being as creative or outrageous as they want,
they have to create a shark that fits the given criteria. If their shark
eats plankton, it most likely would not have big serrated teeth. If it
lives in shallow water, it’s not going to be wide and tall.
5. Allow plenty of time for brainstorming and finalizing copies of their
sharks. Once they’re done they have to introduce their shark to
the class explaining how it survives with the adaptations they’ve
given it.
6. After they have created their shark, have them research the actual
shark, find a picture of it, and write a report comparing the actual shark’s
adaptation to their creative ones.
Assessment
Portfolio Item 1 – Shark picture and report. Self and teacher assessment
questions: Do the adaptations they’ve given the shark allow it to
survive its lifestyle? Did they think carefully and take seriously the
effects of adaptations on a shark’s lifestyle? Were they clear and
confident when explaining their created shark? Were their reports well
thought out and organized?
Resources
- A Look Inside Sharks and Rays. Joshua Morris Publishing, New
York. 1995.
- Ellis, Richard. The Book of Sharks.
- MacQuilty, Miranda. Eyewitness Books – Shark. Alfred A.
Knopf, New York. 1995.
- Perrine, Doug. Sharks Voyageur Press, Inc., Vancouver, B.C.,
1995.
- Simon, Seymour. Sharks. Harper Collins, New York. 1995.
- Springer, Victor and Gold, Joy. Sharks In Question. Smithsonian
Institution Press, Washington D.C., 1989.
Reference Links
Whale
sharks – http://www.njscuba.com/Eco/WhaleSharks/index.html
Shark
Gallery – http://www.shark.ch/Gallery/gallery1.html
Fiona’s
Shark Mania – http://www.oceanstar.com/shark/
Richard
Ellis’ Shark Page – http://www.postmodern.com/~fi/sharkpics/ellis/ellis.htm
Discovery
Channel Sharks: http://dsc.discovery.com/convergence/sharkweek2002/sharkweek2002.html
The
Ultimate Shark Web Site: www.ncf.carleton.ca/%7Ebz050/HomePage.sharklinks.html
Shark Research Institute: www.sharks.org
South African White Shark
Research Institute: www.whiteshark.co.za
Shark Foundation: www.shark.ch/home.shtml
^^back to the top
of the page^^
Lesson 2: How Big is That Shark?
Background Information
Sharks are notorious for being ruthless, mindless hunters who prowl the
ocean depths looking for anything to satisfy their insatiable appetites.
Movies, television and books have long portrayed sharks as bloodthirsty
monsters. In truth, sharks range in size from the 15 meter whale shark,
the largest fish in the ocean, to the 20 cm dwarf dogfishes. All sharks
have preferred feeding strategies and foods for which they are finely
adapted. Among them include large plankton feeders, small carnivores,
and Carcharodon megalodon, the extinct large carnivore that is the ancestor
of the great white. The plankton feeders, including the whale and basking
sharks can reach their immense sizes due to the abundance of plankton
in the water and how often they feed. Because it is more difficult to
support their diet, the carnivores are smaller; their maximum size is
limited by the amount and frequency with which they can feed. This helps
explain why Carcharodon megalodon is extinct.
While sharks do exhibit a wide variety of feeding strategies and food
preferences, none includes humans among the regular items in its diet!
Of the over 375 species of sharks, only about 30 have been known to “attack”
humans only 4-6 are truly considered dangerous – the great white,
bull, tiger, oceanic whitetip, and mako. Annually, there are an average
of 50-75 shark attacks around the world, and only 10-15 are fatal. More
people are killed every year by lightning in Florida, by pigs in Iowa,
by pit bulls in New York City, bees, and hippos than are killed by sharks.
In contrast, we harvest over 100 million pounds of shark meat every year,
the equivalent of approximately 1.5 million fifth graders. Yet our lack
of information and understanding about sharks and their behavior has left
them shrouded in mystery and created a widespread and unfounded fear towards
this misunderstood animal.
Often, when students are asked to think of sharks, they only picture
the great white, made famous by the movie Jaws. They automatically assume
that the great white is the largest and most voracious shark in the ocean.
This activity introduces the wide variety of feeding strategies employed
by the over 375 species of sharks and compares the length of the shark
to its feeding habits and preferences. It also gives students a “real”
idea of how big most sharks really are.
Objectives
To show the wide variety of feeding strategies used
by the different shark species
Students will be able to name the feeding strategies
and preferences of at least 5 different sharks
They will understand that not all sharks are voracious
predators
They will learn that most species of sharks are under
6 feet long
Materials
Index cards with the name of a shark on one side, and the maximum length
and what its diet consists of on the other side (see examples below)
Tape measure that extends to at least 60 feet
Books with pictures of the sharks you’re studying
An outdoor area (parking lot or playground) or long indoor space
Procedure
1. If going outside, discuss safety issues and behavioral expectations.
2. Begin with a discussion to get an idea what the students think about
the size of these animals and what they eat. Which sharks do they think
are the biggest? Why do they think that? How many sharks out there are
larger than us? What kind of things do sharks eat? Do all sharks eat the
same things? If they wanted to be a large shark in the ocean, what would
their food of choice be?
3. Hold up the tape measure and ask one student to take one end of it
and walk out the length they believe the longest shark to be. Once they
stop, check the measurement, and ask another student to take the tape
and show how long they think the largest shark is. Most students will
not walk out 50 feet, if they do, modify the steps accordingly. Ask another
student to take the tape and walk slowly backwards until you tell them
to stop. Stop them between 50 and 55 feet and explain that there is a
type of shark that gets to be that big. Does anyone know what it is? Don’t
discuss what they think it eats yet.
4. Lay down the measuring tape and have all the students come together
again.
5. Give each student an index card, telling them to read their card but
not to show anyone else the information on it. If the class is very large,
divide them into groups or have students work in partners.
6. Have students find the appropriate length of their shark on the measuring
tape and stand alongside it.
7. Tell them to look around, notice where the majority of the students
are standing and who is in front and behind them. Gather them together
in a circle in order. The largest shark will end up sitting next to the
smallest shark
8. In turn, starting with the largest shark, ask each student to tell
the class what shark they are, how big they are, and what they eat.
Discussion/Assessment
Discuss any trends the students noticed – did similar sized sharks
have similar diets? What did the largest sharks eat? The smallest one?
How can a shark that eats plankton get to be so big? Why are the carnivorous
sharks smaller? Why are most sharks small?
Information for Shark Cards
Bull Shark: length – 10 feet
eats – fish, other sharks, dolphins, sea turtles, antelope, small
dogs, hippos (this shark can live in fresh water!)
Nurse Shark: length – 12 feet
eats – crab, lobsters, clams, small fish, sea urchins
Lemon Shark: length – 9 feet
eats – fish, stingrays, crabs, lobsters, clams, seabirds
Spiny Dogfish: length –5 ½ feet
eats – small fish, squid, worms, invertebrates
Cookie-cutter Shark: length – 1 ½ feet
eats – bites of large whales, elephant seals (and other large seals),
dolphins, marlin, tuna
Cigar Shark: length – 9 inches
eats – squid, small fish
Whale Shark: length – 51 feet
eats – plankton!
Basking Shark: length – 48 feet
eats – plankton!
Great White Shark: length – 20 feet
eats – seals, sea lions, other sharks, whales, fish, anything dead
or dying
Tiger Shark: length – 25 feet
eats – just about anything (pieces of cars have been found in their
stomachs)
Great Hammerhead Shark: length – 18 feet
eats – fish, other sharks, crabs, lobsters, stingrays
Bonnethead Shark: length –5 feet
eats – crabs and lobsters, clams, small fish
Horn Shark: length – 4 feet
eats – sea urchins
Blue Shark: length – 14 feet
eats – small fish, squid
Megamouth Shark: length – 15 feet
eats – plankton
Collaborative activities
Further Exploration
Create a shark menu -- give the student the name of a shark and its maximum
length. Have them design a menu of top choice ocean delicacies for this
animal.
Resources
- A Look Inside Sharks and Rays. Joshua Morris Publishing, New
York. 1995.
- MacQuilty, Miranda. Eyewitness Books – Shark. Alfred A.
Knopf, New York. 1995.
- Perrine, Doug. Sharks Voyageur Press, Inc., Vancouver, B.C.,
1995.
- Simon, Seymour. Sharks. Harper Collins, New York. 1995.
- Springer, Victor and Gold, Joy. Sharks In Question. Smithsonian
Institution Press, Washington D.C., 1989.
Links
Whale
sharks – http://www.njscuba.com/Eco/WhaleSharks/index.html
Shark
Gallery – http://www.shark.ch/Gallery/gallery1.html
Fiona’s
Shark Mania – http://www.oceanstar.com/shark/
Richard
Ellis’ Shark Page – http://www.postmodern.com/~fi/sharkpics/ellis/ellis.htm
Discovery
Channel Sharks: http://dsc.discovery.com/convergence/sharkweek2002/sharkweek2002.html
The
Ultimate Shark Web Site: www.ncf.carleton.ca/%7Ebz050/HomePage.sharklinks.html
Shark Research Institute: www.sharks.org
South African White Shark
Research Institute: www.whiteshark.co.za
Shark Foundation: www.shark.ch/home.shtml
^^back to the top
of the page^^
Lesson 3: The Power of “Jaws”
Background Information
Sharks have always been hunted for their meat, skin, and rich liver oil.
Recently, they have also been killed for their valuable fins, used for
making shark fin soup, and cartilage, which purportedly has a variety
of medicinal uses. Fear of sharks, exacerbated by movies such as Jaws,
has created a large shark sport-fishing industry.
Our misunderstandings, coupled with the global demand for shark meat,
skin products, liver oil, cartilage, and fins, have served to aide in
the decimation of most shark species. Compared to the 10-15 people killed
every year by sharks, humans kill over 100 million sharks annually and
many species face certain extinction. In the US alone, coastal species
seem to have declined 50-75 percent in just the last 20 years. Nearly
all shark species have been decimated to the point that they are threatened
or endangered. Most shark species take years to reach reproductive age
and so their depletion is particularly devastating.
Only recently researchers have come to understand the value of sharks
to the ecology of the oceans and have started working to reverse common
stereotypes people have about sharks. An apex predator, sharks act as
agents of natural selection by helping eliminate diseased and weak animals
and helping stabilize population fluctuations. We still don’t know
what all the consequences of losing this vital predator will be on the
environment, but we know that whatever affects one species, eventually
affects the entire ecosystem.
This lesson will help students understand the importance of sharks in
the ocean and the role of the media in shaping our opinions. They will
create a Save the Sharks campaign to educate their schoolmates and increase
awareness of the need for conservation.
Objectives
Students will:
Define the term apex predator and explain their significance
in the food pyramid
Name 5 reasons that sharks are harvested
Strengthen communication skills and creativity
Determine the elements of a successful political campaign
Materials
Paper, pens
Computers with internet access
Poster board, paints, crayons, markers
Informational books about sharks, with lots of pictures
Tape recorders
Shark teeth, jaws, other shark products
Vocabulary
apex predator
producer
conservation
primary consumer
cartilage
secondary consumer
Procedure
1. Ask: Are sharks really all that important? Draw a food pyramid and
have the students help you fill it in with producers, primary consumers,
secondary consumers, and apex predators. The shark is an apex predator
because it is at the top of the food pyramid and has no natural predators
(other than humans). Even though they are way at the top, are sharks still
important?
2. Demonstrate the vital role sharks play in maintaining the stability
of the food pyramid by erasing or covering up the top of the pyramid.
What happens to the level below it (the secondary consumers)? Their population
increases – draw that in. What then happens to the level below that
(the primary consumers)? Their numbers become depleted and can no longer
support the large population of secondary consumers, who subsequently
starve. Removing any organism from any level of the pyramid threatens
the stability of the entire ecosystem.
3. Ask students how many species of sharks there are (over 375). How many
do they think are dangerous? They can probably name the most dangerous
ones – great white, bull, tiger. Hammerhead sharks are no longer
considered as dangerous or unpredictable as they were once thought to
be. Give them the facts about animals and natural events that are more
dangerous than sharks.
4. Have students brainstorm and discuss reasons why we kill sharks, what
we use shark parts for, and why we fear sharks so much. Explain that while
only 10-15 people are killed every year by shark, hundreds of millions
of pounds of shark are harvested.
5. Tell them that they are going to be responsible researching different
aspects of sharks: their role in the ocean, human uses for, myth vs. fact,
etc. Divide the class into groups and assign each group a different shark
or topic to research.
6. When they have finished, bring them together to present their findings.
Discuss whether they believe it is important to work to educate others
and protect this valuable species?
7. If they agree with this statement, or vote as a class, tell them they
are responsible for creating a class “Save the Sharks” campaign
to educate their classmates and the community about the need to protect
these valuable animals.
8. Ask them to interview other students, family and community members
about their feelings and ideas about sharks to determine what education
is most needed.
9. When they have finished their research, they can choose to create posters,
write a newspaper editorial or article, write a script and record an informational
segment for a radio show or news program, or perform a skit or make up
a rap about shark roles or conservation. They should decide as a group
what they want to do and submit a short proposal for approval before they
begin. Make all the materials available for them and make sure everyone
has a job in creating the finished product.
Assessment
Each group should present their poster, article, skit, song, etc. to the
class, describing the research they did and what they learned that led
them to create what they did. Other classes should be invited for these
presentations, or the groups should schedule times to visit other classes
or do an all-school assembly.
Further Exploration
Present a Save the Sharks day for the school and/or community. Organize
letter writing campaigns requesting the need for laws protecting sharks.
Resources
Amato, Carol. The Truth About Sharks. Barron’s, New York.
1995.
Fowler, Allan. The Best Way to See a Shark. Children’s Press,
Chicago. 1995.
Levine, Marie. Great White Sharks. Raintree Steck-Vaughn, Austin,
Texas. 1998.
Links
Discovery
Channel Sharks: http://dsc.discovery.com/convergence/sharkweek2002/sharkweek2002.html
The Ultimate
Shark Web Site: www.ncf.carleton.ca/%7Ebz050/HomePage.sharklinks.html
Shark Research Institute:
www.sharks.org
South African White
Shark Research Institute: www.whiteshark.co.za
Shark Foundation:
www.shark.ch/home.shtml
^^back to the top
of the page^^
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