What zone is the deepest and darkest?

What area is between the high-tide line and the low-tide line?

These are cracks in the ocean floor where there are jets of hot water.

This type of region serves as natural water filters and provide flood protection and erosion control.

Which zone is richer in plant and animal life?

Factors that affect ocean organisms include:

Ponds, lakes, streams and rivers make up what kind of ecosystem?

The ocean makes up what percentage of the Earth's surface?

This area is the part of a river where fresh water meets the sea.