FOOD CHAIN AND FOOD WEB

What is food chain?

Transfer of energy from one trophic level to another  trophic level is called food chain.
Trophic Levels:
The trophic level of an organism is the position it holds in a food chain.

1. Primary producers (organisms that make their own food from sunlight and/or chemical energy from deep sea vents) are the base of every food chain - these organisms are called autotrophs.
2. Primary consumers are animals that eat primary producers; they are also called herbivores (plant-eaters).
3. Secondary consumers eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals that eat both animals and plants).
4. Tertiary consumers eat secondary consumers.
5. Quaternary consumers eat tertiary consumers.
6. Food chains "end" with top predators, animals that have little or no natural enemies.

 For getting better understanding please see this video

Food Web

A network of many food chains is called a food web.

What is the difference between food Chain and a food web?

Food chains follow a single path as animals eat each other.

EXAMPLE:            

The sun provides food for grass

The grass is eaten by a grasshopper

The grasshopper is eaten by a frog

The frog is eaten by a snake

The snake is eaten by a hawk.

Food webs show how plants & animals are interconnected by different paths.

EXAMPLE:

Trees produce acorns which act as food for many mice and insects.

Because there are many mice, weasels and snakes have food.

The insects and the acorns also attract birds, skunks, and opossums.

With the skunks, opposums, weasels and mice around, hawks,

foxes, and owls can find food.

They are all connected! Like a spiders web, if one part is removed, itcan affect the whole web.

Food webs show how plants and animals are connected in many ways toHelp them all survive. 

Food chains follow just one path of energy as

Animals find food.

Learning Activity:  FOOD CHAINS & FOOD WEBS

FOOD CHAINS AND FOOD WEBS – Worksheet

¨       Food Chain:

A food chain is the series of organisms showing feeding relationships.

A food chain almost always begins with a green                   (producer) which is eaten by an                          (consumer).

The arrow means ‘is eaten by’, and shows the flow of matter and energy along the food chain.

There are no                                                 in a food chain because they are so widespread and are not specific to just one food chain.

¨       Example of a Food Chain

Grass(Producer)        Grasshopper(1^st order Consumer)      Kookaburra(2^nd order Consumer)

¨       Producer – usually a green plant that produces its own food by                   

¨       First-order Consumer (also called the primary consumer) – the organism that eats the                                           

¨       Second-order Consumer (also called the secondary consumer) – the organism that eats or derives nutrients from the                                                                  

¨       Herbivore –                                                                                                           

¨       Carnivore – an organism that obtains nutrients from an                                  blood or flesh

¨       Omnivore – an organism which eats both                                                    

¨       Scavenger – an consumer that eats                          animals (e.g. crab)

¨       Detritivore – a consumer that obtains its nutrients from detritus

¨       Decomposer - an organism such as                                      or fungi that breaks down dead organisms and their wastes

¨       Trophic Level – A trophic level is each level in a food                                  . Matter and energy are always ‘lost’ as urine, faeces and heat energy at each trophic level.

¨       Food Web – a                                 of interrelated food chains in a given area