Freshwater
Marine
Transitional
100

This is where a river or stream begins.

What is the waterhead?

100

These organisms produce much of Earth’s oxygen in marine ecosystems.

What are marine algae and phytoplankton?

100

These are areas where water covers the soil or is near the soil surface for part or all of the year.

What are wetlands?

200

Only about this percent of Earth’s water is freshwater.

What is 2.5%?

200

These tiny animals build coral reefs.

What are coral polyps?

200

These wetlands are dominated by grasses and non-woody plants.

What are marshes?

300

This river is the longest river in the world.

What is the Nile River?

300

This zone includes all open ocean water not near the bottom or intertidal zone.

What is the pelagic zone?

300

These wetlands are dominated by woody plants like trees and shrubs.

What are swamps?

400

This is the deepest lake in the world.

What is Lake Baikal?

400

This process happens when stressed corals turn white.

What is bleaching?

400

These ecosystems act as protective buffers and provide environmental services.

What are estuaries?

500

This Amazon animal can produce electricity.

What is the electric eel?

500

This deepest known point of the seabed is about 10,935 meters deep.

What is Challenger Deep?

500

This type of water forms when freshwater mixes with saltwater.

What is brackish water?

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