Ocean Habitat

March 23, 2021

From outer space Earth looks like an awesome blue marble. That’s because most of Earth’s surface—more than 70 percent—is covered by oceans.

EARTH UNDERWATER

Oceans are areas of salty water that fill enormous basins on the Earth’s surface. Even though Earth has one continuous body of saltwater, scientists and geographers divide it into five different sections. From biggest to smallest, they are the Pacific, the Atlantic, the Indian, the Antarctic (sometimes called the Southern), and the Arctic Oceans.

Oceans are deep as well as wide. On average an ocean is a little over two miles deep. But about 200 miles southwest of Guam in the Pacific Ocean, the water in the Mariana Trench is almost seven miles deep. That’s the deepest part of the ocean.

CLIMATE CONTROL

Oceans help keep Earth’s climate habitable. By moving water around the globe, the oceans help to keep places from getting too hot or too cold.

Oceans also help keep the planet warm. In the same way that hot water in a bathtub stays warm longer than hot chocolate in a small cup, the vast amount of warm water stores heat in the ocean. Then ocean currents carry that heat around the planet. Without oceans, the Earth would be an icy rock.

OCEAN OR SEA?

The words “ocean” and “sea” are often used to mean the same thing. A sea, however, is a small area of an ocean, usually with land on several sides. The Mediterranean, nestled between Africa and Europe, the Baltic in northern and central Europe, and the Caribbean between North, Central, and South America are all seas.

OCEAN LIFE

Scientists estimate that about one million species of animals live in the ocean. But most of them—95 percent—are invertebrates, animals that don’t have a backbone, such as jellyfish and shrimp. The most common vertebrate (an animal with a backbone) on Earth is the bristlemouth, a tiny ocean fish that glows in the dark and has needlelike fangs.

WATERY HABITATS

Temperature, ocean depth, and distance from the shore determine the types of plants and animals living in an area of the ocean. These regions are called habitats.

Other ocean habitats aren’t actually in the ocean, such as estuaries. Estuaries are areas where rivers and oceans meet and have a mix of saltwater and freshwater. Oysters, crabs, and many birds like great herons and egrets live in estuaries.

Scientists estimate that we’ve only explored 5 percent of the ocean. Maybe you’ll be the next person to discover a new species of fish or a deeper underwater trench!