What is the difference between oceans and seas

The oceans represent large expanses of salty water that are part of the planet’s hydrosphere. Oceans cover most of the earth’s surface and separate some continents. Historically, four oceans have been considered, until in 2000, the International Hydrographic Organization added the Southern or Antarctic Ocean to this list, so that currently five oceans are considered on Earth :

• Atlantic Ocean : this ocean is found separating the continents of America, Europe and Africa. It occupies an area of ​​approximately 106 million km ² and reaches a maximum depth of 7,750 meters. It is the most important ocean of the five from the point of view of trade flows, both export and import.
• Pacific Ocean : it is the largest ocean in extension of the five, occupying approximately 180 million km ² and a maximum depth of 10,000 meters. It is situated between the continents of Asia, America and Oceania.
• Indian Ocean : it occupies about 74 million km ² between Africa, Asia and Oceania.
• Arctic Ocean : it occupies about 14 million km ² in the Northern Hemisphere.
• Antarctic Ocean : it occupies about 22 million km ² in the Southern Hemisphere.

Seas are large expanses of salty water that may or may not be connected to an ocean , although they usually are. They are generally smaller than the oceans and are shallower than the oceans. The seas do not usually have natural outlets and are close to the Earth. They usually connect the land to the oceans. Unlike the oceans, its waters form waves. The main seas of the planet are:

• Mediterranean Sea : it is the largest sea in the continental interior of the planet, with an approximate extension of 450 thousand km ² and is located between Africa and Asia.
• Baltic Sea : it is a sea in the northeast of Europe and has an area of ​​approximately 420 thousand km ² .
• Aral Sea : It is a sea located in Central Asia and has an area of ​​68 thousand km ² .
• Sea of ​​the Antilles or Caribbean Sea : it is a sea located between Central and South America and has an area of ​​2.7 million km ² .
• Caspian Sea : it is a sea located in southeastern Europe and has an area of ​​371 thousand km ² .
• Dead Sea : it is a sea located in the Middle East and has an area of ​​650 km ² .
• Black Sea : it is located between Europe, Anatolia and the Caucasus and has an area of ​​436 km ² .
• Red Sea : it is located between Africa and Asia and has an area of ​​450 thousand km ² .

The main difference between the two is their size, the seas are smaller than the oceans . In addition, the seas are closed, located between the land and the oceans, while the oceans are open, deeper and with strong ocean currents. Also, there are seas that, due to their size, are considered large saltwater lakes. In this group, the Caspian Sea, the Dead Sea and the Aral Sea can be included.

Due to their greater depth, the oceans reach lower temperatures than the seas , approximately 4 degrees at any point. On the other hand, because the seas are closer to the land masses, they receive greater solar radiation and reach higher temperatures than the oceans, although this is variable between the different seas. Thus, for example, the waters of the Mediterranean Sea are warm and those of the Dead Sea are cold. Precisely, due to their proximity to land, the seas suffer greater desertification with increasing global warming, while the oceans have increased their volume of water due to the melting of the poles and glaciers.

In terms of life, the seas have a greater biodiversity in number of species than the oceans, due to the greater solar radiation they receive, while the oceans are home to fewer species, but more adapted to the depths and low temperatures. The seas, on the other hand, are more exposed to environmental pollution than the oceans and, as a consequence, to a higher mortality of species.