Types of Organisms in an Ecosystem (Leaving Cert Biology): Revision Notes

Types of Organisms in an Ecosystem

Organisms can be split into two categories:

1. Producers (autotrophs): organisms that make their own food using simple molecules e.g. green plants photosynthesise.
2. Consumers (heterotrophs): organisms that cannot make their own food and use food made by others.

Types of Consumers

Primary consumers	Feed on producers. e.g. rabbit, caterpillar
Secondary consumers	Animals that feed on primary consumers. e.g. fox, frog.
Tertiary consumers	Feed on secondary consumers. Generally, the top of the food chain. e.g. hawk, lion.

Herbivores	Organisms that eat plants. e.g. Rabbit
Omnivores	Organisms that eat both plants and animals. e.g. human, pig.
Carnivores	Organisms that eat animals. e.g. hawk, wolf.
Decomposers	Organisms that feed on dead, organic matter. e.g. fungi, bacteria.