1. FOOD WEBS

1.1 What a Food Web Is

A food web is a big network showing who eats whom in an ecosystem. It connects multiple food chains together so you can see how every plant and animal depends on others.

• Shows complex connections between organisms

• Explains how energy and nutrients move

• Helps us understand how nature stays balanced

• Shows how one species affects the whole system.

1.2 Basic Groups in a Food Web

1.2.1 Producers (Plants & Algae)

These legends make their own food using sunlight.

• Grass

• Trees

• Algae

• Small freshwater plants

They’re the foundation because everything else depends on them.

1.2.2 Herbivores (Plant-Eaters)

These creatures get their energy straight from plants.

• Deer

• Rabbits

• Caterpillars

• Grasshoppers

They pass the plant energy to the next level.

1.2.3 Carnivores (Meat-Eaters)

These animals eat herbivores or other carnivores.

• Foxes

• Frogs

• Snakes

• Wolves

They control population sizes and keep balance.

1.2.4 Top Predators (Apex Predators)

These are the final bosses—nothing hunts them.

• Tigers

• Sharks

• Eagles

• Lions

They maintain order at the highest level.

1.2.5 Decomposers

The cleanup crew that recycles everything back into the soil.

• Bacteria

• Fungi

• Earthworms

Without them, nature would drown in waste.

1.3 Why Food Webs Matter

• They show how all organisms depend on each other

• Help scientists predict what happens if a species vanishes

• Show how energy spreads through an ecosystem

• Reveal how ecosystems stay balanced

2. ENERGY FLOW

2.1 What Energy Flow Means

Energy flow explains how energy moves from the sun → plants → animals → top predators.

It always moves in one direction and never gets recycled.

2.2 Levels of Energy Flow (Trophic Levels)

2.2.1 Level 1 — Producers

• Capture sunlight

• Make glucose through photosynthesis

• Store the most energy in the whole system

2.2.2 Level 2 — Primary Consumers (Herbivores)

• Eat plants

• Transfer plant energy into movement & growth

• Lose some energy as heat

2.2.3 Level 3 — Secondary Consumers (Small Carnivores)

• Eat herbivores

• Get less energy than herbivores got

• Still essential for population control

2.2.4 Level 4 — Tertiary Consumers (Big Carnivores)

• Eat other carnivores

• Have even less energy available

• Often fewer in number

2.2.5 Level 5 — Apex Predators

• Highest energy level

• Very few individuals

• Control the entire balance of the ecosystem

2.3 The 10% Rule

Only 10% of energy gets passed from one level to the next.

• Plants → 10% goes to herbivores

• Herbivores → 10% goes to small carnivores

• Small carnivores → 10% goes to big predators

That’s why:

• More grass exists than cows

• More cows exist than tigers

• Top predators are rare

2.4 Why Energy Flow Is Important

• Shows why ecosystems can’t support too many predators

• Helps predict population sizes

• Explains why plants are the base of all life

• Shows how energy is lost as heat at every step.