Food Web
Prepared By: Maria Johanna Baguio Testa
Food Web
A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system.
- Producers (Plant)
- Consumers (Plant or an animal)
- Decomposers (bacteria or fungus)
Producers
- Producers are organisms that produce their own food from the non-living components (soil, minerals, sunlight, CO2) in their environment.
- Green plants are producers. They can produce sugars and starch from carbon dioxide and water, using energy from sunlight by a process called photosynthesis.
Consumers
- Consumers are organisms that eat other organisms or their products.
- Animals cannot make their own food. They depend on plants or other animals for food. Therefore all animals are consumers.
- 1st Primary consumer is usually a herbivore. (Eat Plants)
- 2nd Secondary consumers animals which feed on primary consumers.(eat the primary consumers: ex rats, mantis)
- 3rd Tertiary Consumers are even larger animals which feed on secondary consumers.
Decomposers
- Are organisms that break down dead animals and plant materials into simpler substances which can be used again by green plants.
Examples of decomposers:
- Bacteria
- Fungi
Food Chain
The feeding relationship between producers and consumers can be written in a series of levels called food chain.
Most organisms eat more than one type of food. Therefore, food chains are interconnected.
When a food chains are interlink, a food web is formed. A food web helps to maintain a balanced ecosystem by controlling the number of organisms at each level of a food chain.
Pyramid of Numbers
A pyramid of numbers is a diagram that shows the relative number of organisms at each level of a food chain.
Energy Flow in a Food web and the Pyramid of Number
A food chain or a food web also shows how the energy is transferred from one organism to the another.
Imbalanced food web is when one population in a food web is missing or decreases in number, it will affect the other organisms.
Suppose the snakes in the figure move out of the paddy field for some reasons. The number of rats increase because they have less predators (snake). The number of hawks that feed on the snakes will decrease because these is less food for them.
Bioaccumulation
Bioaccumulation - is the accumulation of toxins by organisms in concentration through food chains.
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost by catabolism and excretion.
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