Food Webs

Food webs describe the eating relationships between species within an ecosystem or a particular living place. When all food chains in a habitat are joined together in some way, they form a food web.
At each stage much energy is lost as heat, a fact that usually limits the number of steps in the chain to 4 or 5. They are normally several food chains all joined up together which may include the same predator or prey in more than one food chain. Every known food chain begins with a producer and ends with a tertiary consumer.

A food web starts with the primary energy source, usually the sun or boiling-hot deep sea vents. The next link in the web is an organism that make its own food from the primary energy source. An example are the photosynthetic plants that make their own food from sunlight, using a process called photosynthesis. These are called autotrophs or primary producers. Next come the organisms that eat the autotrophs. These organisms are called herbivores or primary consumers. An example is a rabbit that eats grass. The next link in the web is animals that eat herbivores. These are called secondary consumers. An example is a snake that eat rabbits. In turn, these animals are eaten by larger predators. The tertiary consumers are eaten by quaternary consumers. Each food web ends with a top predator and an animal with no natural enemies.

Definitions:
Producers: Producers are organisms, such as plants, that produce their own food are called autotrophs.
Consumers: All the organisms that can not make their own food are called heterotrophs. In an ecosystem heterotrophs are called consumers because they depend on others. They obtain food by eating other organisms. There are different levels of consumers.
Herbivores are those that eat only plants or plant products. Example are grasshoppers, mice, rabbits, deer, beavers, moose, cows, sheep, goats and groundhogs.
Carnivores on the other hand, are those that eat only other animals. Examples of carnivores are foxes, frogs, snakes, hawks, and spiders.
Omnivores are the last type and eat both plants also known as primary consumers and meat.


This is an example of a Marine Food Web:

external image arctic_marine_food_web_90.jpg


This is how a food web works:

external image FoodChain.gif

This is an example of a desert food web:

external image desert_chain.gif


This is an example of a forest food web:

external image tempweb.gif


Review Questions:

1. A green plant that makes its own food by photosynthesis is called a:
A. Parasite
B. Producer
C. Consumer
D. Carnivore

2. An organism that eats both plant and animal matter is called the:
A. Producer
B. Carnivore
C. Omnivore
D. Herbivore

3. An organism such as bacteria and fungi that breaks down dead organisms and their wastes is a:
A. Producer
B. Parasite
C. Decomposer
D. Consumer

4. Give some examples of carnivores.



Here is FUN crossword puzzle:
Crossword Puzzle
Answers are on the website!

Answers: 1-B, 2-C, 3-C, 4- Hawks, snakes, frogs, etc.


http://www.scienceclarified.com/Ex-Ga/Food-Web-and-Food-Chain.html
http://www.arcytech.org/java/population/facts_foodchain.html