[Article publié en novembre 2020]
As it stands, there are several criteria. The first is the most intuitive: what distinguishes an ocean sea, It is first of all a scale relationship. By definition, the ocean is more extensive. The area of the smallest of them, the Arctic, is 14.09 million square kilometers, while the largest sea, that of Arabia, covers 3.6 million square kilometers. A relationship from simple to quadruple.
The oceans are bordered by continents
The seas are distinguished by a lower area, but still? The nature of their ribs, the depth of their bottom and the salinity of their waters are also taken into account by oceanographers. By convention, the term ocean designates the largest expanses of salt water, bordered by the continents. There are five of them: Pacific, Atlantic, Indian, Arctic, Austral.
The seas are two main categories. On the one hand, the Bordersarranged along the outline of the oceans, and circumscribed by peninsulas, islands or high fonds. The Caribbean Sea, for example, bordering the Atlantic Ocean, is surrounded by a rosary of islands.
Be careful however, who says sea does not necessarily say “shallow”! That of the edges can be very high, above 2,000 meters, like the Norway Sea (maximum 4,000 m) or the sea of coral (maximum 9,140 m, located between Australia and new Caledonia). But these seas can also be located on continental platforms, less deep than ocean plates, and therefore not exceed 200 meters deep: this is the case of the English Channel or the North Sea.
Landlocked seas have its own characteristics
The second large category, the Annexed seasonscommunicate with the ocean only by a strait and are surrounded by almost all by emerged land. Like the Mediterranean, connected to the Atlantic by the Strait of Gibraltar. Suddenly, unlike the edges, their hydrological characteristics are very different from those of the ocean. Enloped, they are subject to a strong evaporation and are often more salty than the world ocean (the five oceans communicating with each other). While the salinity of the latter is worth 35 grams/liter, in the Mediterranean it varies from 38 to 39.5 g/l, goes up to 41 g/l in the Red Sea and caps at 275 g/L in the Dead Sea! However, in the Baltic, a sea fed by many rivers, it falls at 5 or 10 g/l.
Last difference: The seas display greater biological diversity than the oceans. The Mediterranean, for example, houses between 4 and 18 % of the planet's marine species when it represents less than 1 % of the surface of the world ocean!
According to Science & Vie QR n ° 20 “The sea & the oceans” – leaf through this number – Buy this number
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
