2.  The student will construct a trophic level pyramid and use the ten percent rule to calculate the energy flow.
    Theme 2.3:  Everything is organized a related systems within systems.

A food chain is a transfer of energy from one organism to another. It generally begins with the sun's energy being changed into chemical energy by green plants or producers. Consumers eat (get energy from) the producers. Finally, decomposers break down dead or waste matter and return nutrients to be used again by the producers. Arrows in a food chain
represent the direction of movement of the energy.

             Sun's Energy -> Producer -> Consumer -> Decomposer

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The Ocean Food Chains

Most ocean food chains begin with very tiny floating plants called phytoplankton. These are found near the ocean's
surface where there is plenty of sunlight for photosynthesis (food-making).

Phytoplankton are eaten by floating animals called zooplankton. These are tiny animals or larvae of crabs,
jellyfish, corals and worms.

Zooplankton are food for fish. Bigger fish or mammals eat smaller fish. These bigger fish might include cod,
herring, flounder and sharks. Mammals that eat fish would include seals and various types of toothed whales.

Dead plankton, fish and waste materials fall to the ocean floor to be recycled by decomposers such as bacteria.
Creatures feeding on the ocean bottom (scavengers) include lobsters, crabs, prawns, starfish, sea slugs and worms.
Bottom feeding fish include rays, halibuts, turbots, and gurnards.

One type of zooplankton found here is krill. Krill are tiny shrimp-like creatures. They eat phytoplankton and even
other zooplankton.

Krill are the staff of life for many animals around Antarctica. They also swarm--millions of them swim together.
This makes for an easy, nutritious meal for seals, fish, squid or a large baleen whale.
 
 

                                              Sun's Energy -> Phytoplankton -> Krill -> Humpback Whale

                                                               (A Simple Antarctic Ocean Food Chain)

The concept of biomass is important. It is a general principle which states that the further removed a trophic level is from its source (detritus or producer), the less biomass it will contain (biomass refers to the combined weight of all the organisms in the trophic level). This reduction in biomass occurs for several reasons:

   1.  Not everything in the lower levels gets eaten.
   2.  Not everything that is eaten is digested.
   3.  Energy is always being lost as heat.

It is important to remember that the decrease in number is best detected in terms or biomass. Numbers of organisms are
unreliable in this case because of the great variation in the biomass of individual organisms. For instance, squirrels feed on
acorns. The oak trees in a forest will always outnumber the squirrels in terms of combined weight, but there may actually be
more squirrels than oak trees. Remember that an individual oak tree is huge, weighing thousands of kilograms, while an
individual squirrel weighs perhaps 1 kilogram at best. There are few exceptions to the pyramid of biomass scheme. One occurs
in aquatic systems where the algae may be both outnumbered and outweighed by the organisms that feed on the algae. The
algae can support the greater biomass of the next trophic level only because they can reproduce as fast as they are eaten. In this
way, they are never completely consumed. It is interesting to note that this exception to the rule of the pyramid of biomass also
is a partial exception to at least 2 of the 3 reasons for the pyramid of biomass given above. While not all the algae are
consumed, a greater proportion of them are, and while not completely digestible, algae are far more nutritious overall than the
average woody plant is (most organisms cannot digest wood and extract energy from it).

A generalization exists among ecologists that on average, about 10% of the energy available in one trophic level will be passed
on to the next. This is primarily due to the 3 reasons given above. Therefore, it is also reasonable to assume that in terms of
biomass, each trophic level will weigh only about 10% of the level below it, and 10 times as much as the level above it.  It is useful in terms of human diet and feeding the world's population.  Consider the following: If we all ate corn, there would be enough food for 10 times as many of us as compared to a world where we all eat beef (or chicken, fish, pork, etc.). Another way of looking at it is every time you eat meat, you are taking food out of the mouths of 9 other people, who could be fed with the plant material that was fed to the animal you are eating.

2.  Diagram an Antarctic Ocean Food Chain. Show producers, consumers and decomposers. Visit Antarctica via the internet.

3.  Research zooplankton. What exactly is included in this group of  animals?

4.  Create a trophic level pyramid with labels for producers and consumers.  Be sure to use the 10% rule to calculate the
      number of calories available at each level.  Use 80,000 calories as the producer level.
 

You will be assessed on your creativity,  accuracy, and presentation for activities 1-4 listed above.

Decomposer:  an organsim that eats dead or decaying plants and animals; examples include scarab beetles and bacteria

Producer:  an organism that makes its own food; includes green plants and some types of bacteria