Trophic levels show us how energy moves through different living things in an ecosystem. Each trophic level tells us what place an organism has in a food chain. A food chain is organized into several layers:

1. Producers (Trophic Level 1): These are mainly plants and tiny ocean plants called phytoplankton. They make their own energy using sunlight through a process called photosynthesis. Only about 1% of sunlight gets turned into energy by these producers.

2. Primary Consumers (Trophic Level 2): These are herbivores, which are animals that eat plants. They get around 10% of the energy from the plants they eat. This is known as the Rule of 10%.

3. Secondary Consumers (Trophic Level 3): This level is made up of carnivores that eat the herbivores. They only receive about 1% of the energy from the sunlight that the producers originally captured.

4. Tertiary Consumers (Trophic Level 4): These are top predators that eat the secondary consumers. They get just about 0.1% of the original sunlight energy.

At each level, energy is lost for various reasons, like breathing, digesting food, and generating heat. Usually, only around 10% of energy moves from one level to the next. This leads to less energy and less living matter (or biomass) as you go higher in the levels. For example:

• If producers start with 1000 kcal of energy, primary consumers will get roughly 100 kcal.
• Secondary consumers will have about 10 kcal, and tertiary consumers will get only about 1 kcal.

This shows how energy flow in ecosystems is not very efficient. That's why food chains usually have only four or five trophic levels.