Perch in giant kelp forest Click on image for full size (425 Kb) Courtesy of NOAA

There are many different types of living things that call the ocean home. The smallest creatures are so tiny that they can only be seen with a microscope. The largest creatures are blue whales, which can be as long as three school buses.

There are many different ways to live in the ocean, too. Some animals travel through the water. Others stay in the same place on the ocean floor for their entire lives. Some dig beneath the sand. Others float near the surface.

The ocean is not the same everywhere.  The temperature of ocean water, the amount of sunlight, and the amount of nutrients change from place to place.  Different creatures can live with different conditions.

Almost all marine life lives in the top layer of the ocean where sunlight shines through. Living things like plants make their own food using sunlight through the process of photosynthesis. They are the start of most food chains in the ocean.

Ocean water closer to the poles is colder than ocean water that is closer to the equator. Water that is deep in the ocean is colder than water that is near the ocean surface. Many animals can only survive at certain temperatures.  Other animals in the ocean are able to survive at a range of temperatures and can live in more places in the ocean.

The links below describe four different environments in the ocean that living things call home. 

• Life in the Intertidal Zone
• Life in the Open Ocean
• Life in the Shallow Ocean
• Life in the Deep Ocean