1. Page 5 In Your Unit 7 Notebook
Trophic Levels
Page 5 In Your Unit 7 Notebook

2. What is a trophic level?
- A trophic level is a level of nourishment in a food chain.
- Food chains are made up of 4 trophic levels. They show how energy passes from one level to the next.

3. 1st Trophic Level
The trophic level at the bottom of the food chain is called the primary producer.
These organisms are autotrophic – they make their food using the energy of the sun.
Examples include plants, phytoplankton, algae, and kelp.

4. 2nd Trophic Level
The trophic level that eats the primary producers is called the primary consumer.
These organisms are herbivores – they get their energy by eating non-animal organisms.
Examples include cows, caterpillars, deer, and bees.

5. 3rd Trophic Level
The trophic level that eats the primary consumers is called the secondary consumer.
These organisms are small carnivores and omnivores – they get their energy by eating non-animal organisms and small herbivores.
Examples include doves, finches, bears, and foxes.

6. 4th Trophic Level The final trophic level is called tertiary consumer.
These organisms are larger carnivores or top predators.
Examples include killer whales, hawks, lions, or sharks.

7. Energy Transfer
As energy moves up the food chain, most of the energy gets lost as heat.
Only about 10% of the energy from prey is gained by the predator. This is called the Rule of 10.
So to feed 1 (kilogram) kg of top carnivore (tertiary consumer), you need 10 kg of primary carnivore (secondary consumer) – like in the energy pyramid to the right.