We have five oceans and they are the Pacific, Atlantic, Indian, Arctic and Southern. There are also many seas. Seas are often partly closed by land. The largest seas are the South China Sea, the Caribbean Sea and the Mediterranean Sea. The oceans cover 71% of the Earth’s surface and contain 97% of the Earth’s water.
We need the earth’s oceans to moderate temperature. They do this by absorbing solar radiation, which is then stored as heat energy. The currents then distribute this heat energy around the world.
The Oceans are all connected and until recently, we had only four recognized Oceans – The Pacific Ocean, The Atlantic Ocean, The Indian Ocean and The Arctic Ocean. In the year 2000, The International Hydrographic Association decided to delimit a new ocean – The Southern Ocean.
An ocean is divided in to five zones according to how far down sunlight penetrates.
• The epipelagic, or sunlit zone is the top layer of the ocean. Enough sunlight penetrates so plants can carry on photosynthesis.
• The mesopelagic, or twilight zone is a dim zone where some light penetrates, but not enough for plants to grow.
• The bathypelagic, or midnight zone is the deep ocean layer where no light penetrates.
• The abyssal zone is the pitch-black bottom layer of the ocean. The water here is almost freezing and its pressure is immense.
• The hadal zone is where water is found in the ocean´s deepest trenches.
