Water Biome: Saltwater

Most of the earth is covered by ocean.
Oceans give us food and a place to play.
Oceans help keep the air temperature steady.
On the ocean bed there are mountains, valleys and even volcanoes.

The watery planet
Nearly three quarters of the earth's surface is covered by water. About 97% of that water is ocean. The rest is frozen in glaciers and icecaps, or in lakes, rivers or in the air.


What the ocean gives us
The ocean provides us with food, energy and minerals. It allows us to swim, sail in boats, surf and other activities. The ocean helps regulate the air temperature and supplies moisture for rainfall.

Under the ocean
The bottom of the ocean has high mountains, wide plains and deep valleys. There are even volcanoes on the ocean floor. Mostly the ocean is about 4000 metres deep, but is deeper in places. The deepest known point is in the Mariana Trench, north of New Guinea. The Mariana Trench is stretches for about 2,500 km, and ranges in width from 70km to 338km. The deepest point of the Mariana Trench is called Vitjazdepth and is 11,035 metres deep. This is the deepest part of Earth that we know about.

Salty water
Oceans are salty, mostly from sodium chloride, or the salt we use on our food. Minerals and salts come from rocks on land, which get washed down into the ocean. Rain falls on the land and the water filters through rocks and sand and collects salts as it makes its way into the ocean. Salts are also released by underwater volcanoes. The sun evaporates water, which turns into vapour and becomes part of the air, leaving the salt behind. So the oceans become saltier and each time freshwater from rain or rivers goes into the ocean, it becomes salty . There is more evaporation in tropical areas, so the ocean is saltier there. However, close to the equator there is a great deal of rain, which returns lots of fresh water to the ocean. Therefore, around the equator, the ocean is less salty.

Sections of the ocean
Continents divide the ocean into sections. The largest is the Pacific Ocean, then the Atlantic Ocean and the Indian Ocean. Each ocean has smaller parts called seas, gulfs or bays. These are at the edges of oceans.Where the Pacific, Atlantic and Indian Oceans meet near the continent of Antarctica, the waters are called the Antarctic or Southern Ocean.

Food from the ocean
Food provided by the ocean is fish, shellfish, and seaweed. Kelp, a kind of seaweed, provides algin, which is used as a thickening in ice cream, salad dressing and cosmetics.

©[2008] Jupiterimages Corporation

Fish farming, or aquaculture, is increasing in western countries. It has been practiced in Asian countries for hundreds of years. Fish farmers raise fish, shellfish and seaweeds in special ponds or along the seashore.

©[2008] Jupiterimages Corporation

Energy from the ocean
Oil and natural gas are the main energy resources provided by the ocean.

any creatures live in the ocean, from tiny organisms to the largest mammal, the blue whale. Many other creatures spend much of their time in or near the ocean, such as penguins and seals.

How does the ocean get salty?

More ocean information:
Some Ocean Facts Australia's Great Barrier Reef Animals that live in oceans

Water Biome: Freshwater

Water - what is it? The Water Cycle

Find out about other biomes:

rainforest tundra desert
deciduous forest grassland taiga

If you use any part of this in your own work, acknowledge this source in your bibliography like this:
Sydenham, S. & Thomas, R. Water Biome: Saltwater [online] www.kidcyber.com.au (2000)

April 2013 copyright © kidcyber

 Please contact kidcyber if you find broken links etc. that need repair.


Back to Planet Earth
 Map courtesy of ITA's Flags of All Countries used with permission.