How do energy and nutrients flow through an ecosystem?
Let me tell you a short story ;D
The sun shines on a field of grass and gives it energy to grow. A rabbit comes hopping along, stops to nibble on the grass, and gets energy from the meal. Hiding behind a bush, a fox comes out and tries to catch the rabbit. The rabbit sees the fox and tries to escape. The fox chases the rabbit. the chase ends when the fox catches the rabbit, and it becomes food for the fox, which in turn gets energy from this meal.
This is how energy and nutrients transfer from one organisms to another.
Energy and nutrients are transferred from producers to consumers to decomposers.
Producers :
- produce food not only for themselves but for all other organisms, either directly or indirectly
eg. when the rabbit eats the grass, it gets the food energy stored in the plants directly, but when the fox eats the rabbit, the fox gets the plant food energy indirectly through the rabbit.
Consumers :
- cannot make their own food, and obtain energy by feeding on other organisms
1) Herbivores(plant-eaters)
- feed directly on plant(producers) to gain energy, hence they are known as primary consumers
2) Carnivores(meat-eaters)
- feed on meat to gain energy BUT,
i) those that feed on herbivores are known as secondary consumers
ii) those that feed on carnivores are known as tertiary consumers
3) Omnivores
- feed on both plant(producers) and animal(consumers) to gain energy
4) Decomposers
i) obtain energy by :
- breaking down the remains of dead plants and animals into nutrients
- break down the waste materials of living organisms
ii) allow materials to be used again by green plants
Food chain
- a food chain is like a ladder, with animals at each step
- series of organisms through which energy is transferred in the form of food
- each organism in a food chain feeds on the organism before it and provides food for the organism after it
- each step is known as a trophic level(usually not more than 4 levels) :
Producer ---> Primary Consumers ---> Secondary Consumers ---> Tertiary Consumers
(green plant) (herbivore) (carnivore) (carnivore)
- A FOOD CHAIN ALWAYS BEGINS WITH A PRODUCER
Food web
Ever ponder over this?
What would it be like if animals in the wild ate the same thing day after day?
Not only would their life lack variety, but it would also be precarious.
What would happen if lion could eat only zrbras?
If a natural disater wiped out the entire zrbra population in an area, the lions that live there would lose their only food source.
Soon, they too would die out.
- food chains combine together to form a food web
- food chains are interrelated because animals do not eat the same food every meal
Lets use a spider web as an example
if a couple of strands are broken, a spider web can still keep its shape.
but if too many strands break, the whole web is in danger of collapsing
jus lik a food web, when one population dies out, the other populations can still depend on other food sources to survive as they do not eat the same food every meal right?
but if too many populations dies out, the whole community might 'collapse'
