Oceans and seas splash on the same square kilometers of the earth’s surface, and because the use of the two terms could coincide, you need to know some facts that will help you distinguish them.
What is a sea?
The most popular definition is ‘the sea is a part of the ocean, separated by land or islands’. Yes, a sea is a part of the World Ocean. It can be separated from it by the features of the sea floor (like in the case of the Sargasso sea), by archipelagos or series of islands (like in the case of the South China Sea or the Baffin Sea) and by peninsulas or outlines of continents (like in the case of the Arabian or Mediterranean seas). Due to the obstruction of the sea's connection with the ocean, they tend to have their own separate hydrological regime, temperature, salinity, transparency, current systems, flora and fauna.
There are 63 seas in the world today. All of them are divided into 2 groups according to their degree of isolation from the parent ocean; the first division includes the seas that are widely open to the open ocean at the surface, while the second includes the marginal seas.
The widely open seas are deeply embedded in the mainlands. Examples are the Mediterranean, Marble, Black or Baltic Seas. They are connected with their ocean by a system of straits and have pronounced differences in the level of salinity and endemicity of the living organisms that inhabit them.
Marginal seas are located along the coasts of the continents. They have a smaller degree of isolation from the ocean, and the waters of both objects are actively mixed. Examples of such seas are the Tasman Sea, the Norwegian or East China sea.
The Saragossa sea is special because it generally does not have any shores. It is located in tropical latitudes, in the middle of the Atlantic Ocean. There are also certain water bodies called seas that are not really seas, examples are the Caspian sea and the Dead sea. According to the usual set of characteristics, these two water bodies are more like lakes.
What is ocean?
The ocean is a water space covering most of the earth's surface and surrounding continents and islands. The ocean is part of the world’s ocean. In total, there are four different oceans according to the national classification - Pacific, Atlantic, Indian and Northern Arctic. Children in a number of foreign schools also learn about the Southern Ocean - one that surrounds Antarctica and is limited by the course of the Western winds.
In some other countries, it is said that the Arctic Ocean is not an ocean, but only a giant sea belonging to the Atlantic Ocean. Each of the oceans has its own unique floor, temperature regime, salinity and flow system. At the same time, there is a wide exchange of water amongst them and one can travel from one ocean to another because they form a continuous, inseparable ‘body’. The borders of the oceans are the continental slopes, separate islands and meridians, lowered from the extreme points of South America, Africa and Australia to Antarctica.
The four different oceans put together occupy 71% of the earth's surface, and based on this fact, a lot of people have developed the opinion that the earth is not properly named, because it is more logical to call it the Ocean or Aqua, which would reflect the large distribution of water masses on the planet better.
What is the difference between an ocean and a sea?
- The sea is a structural unit of an ocean. The latter is part of a single World Ocean, occupying two-thirds of the earth.
- The ocean is much larger than any sea.
- There are only 4 oceans and about 63 seas on earth.
- In the ocean there are both warm and cold surface flows, but seas usually have either warm or cold surface flows.
- The oceanic crust serves as the ocean floor, while the sea shelf is the continental shelf; except in the case of Philippine and Sargasso.
The difference between a sea and an ocean is not well known to everyone, most people just choose to call some parts of the water areas the seas, and others the oceans. In general, only specialists seem to know the difference between them, however now you do too!
Which sea do you dream to visit? Or do you like the ocean more? Share your answers in the comment section below!