food chains and predator-prey cycles

Every food chain starts with a producer. In most food chains the produces is a green plant e.g grass—> rabbit—→ fox

In the sea the producer could be an algae such as seaweed.

Producers are important in food chains because they synthesise complex molecules.

Producers are the source of all the biomass in a community which is very important.

Organisms that eat the producers are called primary consumers. The primary consumer is then eaten by another animal—> these animals are called secondary consumers.

So secondary consumer is an animal that eats the primary consumer.

The secondary consumer is eaten by a bird of prey.

—> A tertiary consumer eats a secondary consumer.

Consumers that kill and eat other animals are called predators.

The animal that is being eaten is the prey.

The numbers of predator and prey rise and fall in cycles. For e.g imagine that one year, the population of rabbit increases, it could be a warm summer so there is plenty of grass for rabbits to eat this mean more of rabbits offspring survive and rabbit population increases. And now the foxes have more rabbits to kill and eat so after some time the foxes population increases. However because there are more foxes this means more rabbits will be eaten. Now the population of rabbits falls. Now foxes have fewer rabbits to kill and eat so after some time the population of foxes also falls. Because of this more rabbits will survive and reproduce so population of rabbits now increase. Now there are more rabbits for foxes to kill and eat the population foxes increases again. —→ THIS IS ONLY TRUE IN A STABLE COMMUNITY. stable community is when all of the biotic and abiotic factors are in balance.

If something changed in the community for eg a drought happens or a new predator arrives then predator-prey cycles would start to change.