The Food Web
The food chain consists of four main parts:
- The Sun, which provides the energy for everything on the planet
(except organisms living near the hydrothermal vents).
Producers: these include all green plants. These are also
known as autotrophs, since they make their own food. Producers are
able to harness the energy of the sun to make food.
In the ocean, the producers are the phytoplankton. It is estimated that
500 billion tons of phytoplankton are produced each year.
Consumers: In short, consumers are every organism that eats something
else. They include herbivores (animals that eat plants), carnivores
(animals that eat other animals), parasites (animals that live
off of other organisms by harming it), and scavengers (animals that
eat dead animal carcasses).
In the ocean food chain, the zooplankton eat the phytoplankton. These in
turn are eaten by larger zooplankton and then by fish. It is
estimated that for the 50 billion tons of zooplankton are produced each year
which support 200 million tons of fish. Thus, the oceanic food chain is has a low
efficiency, since much energy is lost through the 3 to 6 levels of
Decomposers: These are mainly bacteria and fungi that convert dead
matter into gases such as carbon and nitrogen to be released back into
the air, soil, or water. Fungi, and other organisms that break down
dead organic matter are known as saprophytes.
Decomposers are necessary since they recycle the nutrients to be used again