Activity Background Information
Our sun is the ultimate source of all energy. Green plants, called PRODUCERS, contain the pigment chlorophyll. They are able to convert the sun's energy into plant material by the process of photosynthesis.
Green plants may serve as a source of food for animals like the cottontail rabbit. Animals that are primarily plant eaters are called HERBIVORES. Herbivores eat plants and, as a result, are able to produce animal tissue that may server as food for meat eating animals such as the gray fox.
Animals that are primarily meat eaters are called CARNIVORES. (Carnivores may be further designated based upon the specific kinds of animals they eat. For example, INSECTIVORES are carnivores that chiefly eat insects.) Most Pinelands carnivores have diets that are relatively broad; therefore, food preferences for these animals may change seasonally as the amount and availability of foods vary. ( As an example, a gray fox may eat mice when they are numerous, then eat rabbits when mice become scarce, eat berries when they are in season, and switch to grasshoppers in the fall.) Many carnivorous animals of the Pinelands would be better classified as OMNIVORES, animals that eat both plants and animals.
All plants and animals eventually die. Those animals and plants that are responsible for the rotting or decay of dead plant and animal material are called DECOMPOSERS. Decomposers are an important part of all food webs because they return nutrients to the soil or water where they may be reused by the producers, green plants. Examples of decomposers are microscopic plants and animals known as bacteria and fungi, earthworms, and insect larvae such as maggots (fly larvae) and grubs (beetle larvae).
Procedure:
Part
I:
Give each student a copy of the "Energy Flow" worksheet. Ask
students to cut out each shape and ask them to arrange them to show the
way food (energy) flows from one organism to another. The shape at the
base of the form is the ultimate form of energy. It should be noted that,
when arranged correctly, the four shapes form a pyramid. This representation
of the flow of energy from one organism to another is called a food pyramid.
Ask students why they believe that the shape of a pyramid is appropriate
for this concept. (Answer: According to the Second Law of Thermodynamics,
as energy changes its form, there is a loss of available energy with each
transformation. For example, as energy flows from the sun to plants to
animals there is a loss of energy with each transformation. With less
available energy at each level, the number of organisms at each level
is reduced. The narrowing of the pyramid from base to tip graphically
represents this loss. It should be noted that not all food pyramids have
four levels-some have more, and some have less. Sun to rice to man would
be a three level pyramid, while sun to grain to grasshopper to frog to
trout to man would be a six level pyramid.
Part
II:
Give
each student a copy of the "Pinelands Animal Classification"
worksheet. Have students place each of the animals listed under the herbivore,
carnivore, or omnivore headings. Students should be prepared to justify
their placement of an animal by giving examples of the food that they
might eat.
Part
III:
Assign each student on or more 3 x 5 cards with an animal's name printed
on the front. You can take animal names from the list of "Dominant
or Distinctive Vertebrates of the New Jersey Pine Barrens" linked
to above. Have the students research what their animal's primary food
sources are, as well as what other animals might eat this animal as a
food source.
Part
IV:
The next day the teacher will place on the chalkboard the words SUN and
GREEN PLANTS. The sun represents the ultimate energy source, and green
plants represent producers. Have each student place his/her animal's name
on the board. When all the animal's names have been placed on the board,
draw arrows to show how energy flows to and from each organism (example:
sun to plant to animal). It is recommended that you have students assigned
herbivores place their animal names on the board before any others as
this will help to clarify the complex interrelationship between many animals,
i.e. rabbits (herbivores) might be eaten by both owls and timber rattlesnakes
(carnivores). This graphic representation that you will develop on the
board is known as a food web. Discuss how man fits into this food web.
Note that man is an omnivore that eats both plants like blueberries and
cranberries as well as animals like deer. Discuss how man's activities
like housing developments, pollution, farming, pesticides, etc. influence
the food web where man lives.
EVALUATION:
Question students to ascertain their understanding of the terms producers, herbivores, and carnivores and the relation of these roles to each other. Students should be able to explain how the sun can be regarded as the ultimate source of energy for an ecosystem, and the role that decomposers play in returning nutrients back into the ecosystem. You may want to consider assigning students an essay based on man's influence on Pinelands food webs. Points that should be touched upon in the essay are: man's role in the food chain as an omnivore, the influence of man's activities (housing, farming, pollution, insecticides, etc.) on Pinelands food webs, how Pinelands development is subject to study of the impact of a project on the food web, and how man can be beneficial to the food web (habitat preservation).
Follow Up Activities:
1.Have students construct food webs for specific locations such as their backyards, the school yard, or a local pond or park. You might consider having students look at the web over a span of one or two seasons, to determine how, for example, the food web of summer is different from the food web of winter. Students should be encouraged to speculate on how the seasonal food web influences the fact that certain animals are only found at certain times of the year
2. Have students set up an aquarium or terrarium. In the planning process, be sure to have the students keep in mind the need for energy (sunlight), producers, herbivores, and carnivores. If the aquarium or terrarium is well planned, it is possible that it will be maintenance free and could remain viable throughout the entire school year. Students should keep observations of the project in a notebook, and report on changes they notice during the school year.
This lesson will introduce the students to the following vocabulary words:(Click on a word to see its definition-use your browser's BACK button to return to this page)
carnivore, decomposer, food pyramid, food web, herbivore, insectivore, producer
Science standards:
5.1-All students will learn to identify systems of interacting components and understand how their interactions combine to produce the overall behavior of the system.
5.6-All students will gain an understanding of the structure, characteristics, and basic needs of organisms.
5.7-All students will investigate the diversity of life.
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