Animals get the nitrogen they need by eating plants or other animals that contain nitrogen. When organisms die, their bodies decompose bringing the nitrogen into soil on land or into ocean water. Bacteria alter the nitrogen into a form that plants are able to use.

Can animals use free nitrogen?

However, most organisms, including plants, animals and fungi, cannot get the nitrogen they need from the atmospheric supply. ... Certain types of bacteria are able to use the free nitrogen in the air to make nitrogen compounds through a process called nitrogen fixation.

What is the usable form of nitrogen for animals?

Nitrates can be used by plants and animals that consume the plants. Some bacteria in the soil can turn ammonia into nitrites. Although nitrite is not usable by plants and animals directly, other bacteria can change nitrites into nitrates—a form that is usable by plants and animals.