The 4 differences between sea and ocean, explained

A summary of the keys to distinguish between an ocean and a sea.

Water (H2O) in its liquid form is the most abundant fluid in the world, accounting for 525 million cubic kilometers of water, or 70% of the earth's surface.

Interestingly, the amount of water present in the planet's crust has neither increased nor decreased over the last 2 billion years: each of these molecules is transformed and forms part of the biogeochemical cycles of ecosystems, but does not disappear. Of all this percentage of terrestrial water, 20% is underground or forms part of atmospheric gases.

Over a period of 100 years, a molecule of H2O spends 98% of its time sailing the oceans, 20 months in the form of ice, 20 months in the form of ice, and 20 months in the form of water.20 months in the form of ice, 2 weeks in lakes and rivers and less than 7 days in the form of atmospheric gas. This entire hydrological cycle is outlined without taking into account that water also passes through the bodies of organisms, since we must not forget that 60% of an adult human being is this fluid.

This data is fascinating when put into perspective, as it shows that a water molecule makes a dizzying journey through each phase of the hydrological cycle, traveling distances that a human being cannot even conceive of. This interesting train of thought leads us to a basic question, but one that is difficult to resolve: What are the differences between the sea and the ocean?

The 4 differences between the sea and the ocean

Many times, when we find terminological conflicts in the Spanish language, it is worth asking ourselves what their meaning is in English and other languages. In this case, the word Ocean refers to the ocean in English, while the sea is called sea. In both languages this dichotomy is present, so some scientific and substantial differences must exist between the two terms. We explore them below.

1. Seas are smaller than oceans

The Real Academia Española de la Lengua (RAE) defines the sea as the mass of salt water that covers most of the earth's surface, each of the parts into which the sea or a lake of a certain extension is considered to be divided. On the other hand, this same organism argues that the ocean is a sea of great extension that separates two or more continents.

With these definitions, which are more linguistic than geological, the question is not resolved. However, the National Ocean Service (NOAA) gives us a much more convincing answer: seas are smaller than oceans, and are generally conceived of as the point of connection between the land (beach) and the deep ocean.. Typically, seas are partially bordered by land at their boundaries.

Take the Mediterranean Sea as an example. This sea (not ocean) is enclosed between continental land masses, and only communicates with the outside thanks to the Strait of Gibraltar. On the other hand, it is surrounded by Europe, Africa and Asia. Beyond its geographical situation, it should be noted that the Mediterranean Sea is divided into other sub seas, among which are the Lesser Sea, the Lesser Sea, the Libyan Sea and the Levantine Sea (of 15 total).

2. There are many more seas than oceans

Even if only because of their smaller size, it is not difficult to deduce that there will indeed be more seas than oceans on Earth. According to the International Hydrographic Organization (IHO) there are a total of 60 seasno more and no less. Some of them will surely ring a bell: the Baltic, the Caribbean, the Mediterranean (already mentioned), the Black, the Red, or the Andaman, among others.

On the other hand, we can only mention 5 oceans in the entire surface of the Earth.. We name them and tell you some of their characteristics in the following list:

• Antarctic Glacier: its adjacent continent is Antarctica and covers 20,327,000 square kilometers. It has a depth of 3,270 meters.
• Arctic Glacier: it is adjacent to North America, Asia and Europe. It occupies 14,056,000 square kilometers and has an average depth of 1,205 meters.
• Atlantic: it is in contact with America, Europe and Africa. It covers 106,500,000 square kilometers and is 3,646 meters deep.
• Indian Ocean: it borders Africa, Asia and Oceania. It occupies an area of 68,556,000 square kilometers and has an average depth of 3,741 meters.
• Pacific: the adjacent continents to this ocean are Asia, America and Oceania. It has an area of 155,557,000 square kilometers and a depth of 4,280 meters.

The same organization cited above estimates that, in these oceans, a total of 1,332 million cubic kilometers of water can be calculated. Summarizing this point, there are 12 times more seas than oceans in the world, but the oceans are much more vast and extensive.

3. There are seas that are lakes

It may sound counter-intuitive, but there are certain bodies of water enclosed in continental land that are called seas.. This does not happen in any case with the oceans: we remember that they are only 5 and collect most of the water of the earth's crust.

Some examples of this curious conflict of nomenclature are the Dead Sea, the Caspian Sea and the Aral Sea. For example, the Dead Sea (bordering Israel, the West Bank and Jordan) is a 605 square kilometer saltwater lake. It is famous for how easy it is to float when swimming in it (due to its very high salinity), but it also has a very special black mud, which stands out for its pharmacological properties.

4. Different climatic conditions and changes in biodiversity.

Due to their depth and extension, the oceans have much colder waters, with an average temperature of 4 degrees Celsius.The oceans, with an average temperature of about 4 degrees Celsius, are much colder. The living beings that inhabit these demanding places have developed different strategies to maintain heat, despite being unable to generate it at the metabolic level.

For example, the leatherback turtle (Dermochelys coriacea), a reptile usually classified as "cold-blooded", keeps its body 8 degrees above ocean water temperatures, due to thermogenesis produced by its muscular movement.

The oceans are very demanding ecosystems on a Biological level, since the living beings that live in them do not have the sea floor at their disposal and light does not reach them, so the trophic chain of the oceans is very complex.The food chain is greatly limited (as there are no plants or algae available). As you can imagine, in the seas things are very different, since the solar incidence (depending on the depth) is more present and temperatures can be a little higher.

Because of this, the fauna and flora in the seas is much more overwhelming than that of the oceans, since there are algae, invertebrates, fish, mammals (and even birds) that form food chains based on solar radiation and photosynthesis by algae. The areas where life is most prolific are hemipelagic, i.e., they are found on continental shelves.. This is where most of the marine biodiversity develops.

The oceanic water block can be divided into pelagic (light reaching), mesopelagic, bathyal and abyssal zones. Due to the lack of direct contact with other land sources, life here is much scarcer.

Summary

As you may have noticed, the main difference between a sea and an ocean is always the extension and location. A sea (usually) is shallower, covers less surface area and is surrounded on some of its boundaries by continental land masses. The oceans, on the other hand, are 5 deep, deep, unmanageable bodies of water, with abyssal levels and the capacity to hold most of the water present on the Earth's surface.

In other words, there are only 5 oceans, but each of the 60 seas are circumscribed around them. The seas act as bridges between the oceans and the Earth, but both are conceived within the general concept of intercontinental land masses.