Sea and Ocean
Sea and ocean are both water bodies yet they share many differences and similarities among them. We may think that both just contain water in them and what might be the possible difference, but still, there are major differences, facts, and points about both that separate them from each other.
What is an Ocean?
Oceans are water bodies that incorporate more than 70% of the earth’s surface. There are five oceans in the world. Namely the Pacific Ocean, Indian Ocean, Arctic Ocean, Atlantic Ocean, and the Southern Ocean. Oceanography or oceanology is the study of physical and biological characteristics and features of the ocean and its organisms. The ocean water is alkaline and makes them unfit for drinking. The rivers have carried the minerals, rocks, and soil from the land and brought them to the ocean, which makes the ocean salty. The minerals are mostly sodium and chloride which make up the common salt.
It can be seen that oceans are not bordered or separated by any landmarks. Hence, all the oceans combine to make a single large water body on the earth’s surface. To our convenience, we have grouped the ocean based on its location. The Arctic ocean is named after the arctic region likewise the Indian ocean is named after India which is approximate to the ocean.
It is observed that the oceans that approximate the north and the south poles are less saline in nature than the oceans which are situated more towards the equator. This is because the tropical region receives more sunlight than the poles. So the water in those regions evaporates faster and concentrates on the water.
The color of the ocean is mostly blue as perceived. It would be fascinating as we have learned that water does not have any color yet we perceive oceans and seas in blue color. This is because the sunlight that is emitted on the water bodies has different wavelengths of light. The red part of the sunlight is absorbed resulting in the blue color of the light being reflected back to the atmosphere.
Tides
Tides are the rising and falling of water in the ocean and other water bodies. It is mainly seen in large water bodies like oceans and seas. The tides are caused due to the exertion of the moon’s gravity on earth. Since the moon revolves around the earth, it exerts a gravitational pull towards the earth’s surface. Since the earth rotates around its axis, the side facing the moon experiences a high tide which is a bulge in the ocean. Which keeps changing as the earth keeps rotating. On the day of a full moon and new moon, the earth and sun and moon align with one another causing a maximum bulge in the ocean. These are called High Tides. And the area opposite to the earth’s surface will experience low tides. Hence, oceans keep experiencing high tides and low tides frequently throughout the time of rotation and revolution.
Waves
Waves are the motion of water in oceans caused by the wind. The wind shifts some of the energy to the water molecules when it moves over the surface of the ocean. This causes water to move in oceans and seas. It may seem that waves are moving in a horizontal direction, but they just move vertically.
What is a Sea?
Seas are the water bodies that are smaller than the ocean, and partially landlocked on either of the sides. There are few seas that are fully landlocked saltwater lakes like the Caspian Sea or the Dead Sea which is technically a lake but still called Sea. There are also seas that contain freshwater, one example is the Sea of Galilee.
The seas also have similar features as that of the oceans. It also consists of waves, tides, and water currents. Sea currents are the flow of the water within the sea which travel in different directions based on geography, temperature, wind, and ocean currents. The salinity of the sea is measured with the unit of parts per thousand (%), the normal seawater is very alkaline. It normally ranges about 35%, but the seas like the Mediterranean Sea are about 38%. In landlocked saltwater lakes, the density of the salt in water is too high ranging about 300% given an example of the dead sea.
A water cycle is the main event that takes place in almost all the water bodies. The water from the seas, oceans, lakes and other water bodies evaporates into the sky forming clouds. The clouds become denser and start cooling down eventually, causing the water to come back to the earth in the form of rain. This event is very important as rainwater plays a major role in plant growth, agriculture, and many other events.
Coasts
Coasts are an important feature of seas. It is the point where the land meets the water body. The coastline is the total length of the area that surrounds the land, particularly when we look into the geography of a land. Beaches are areas covered with sand and rocks near the sea where people may come to relax for a vacation.
Creatures of the Sea
Marine life are extremely important for the survival of the biosphere, as the carbon cycle is regulated by the creatures of the sea and ocean. The range of creatures living in the sea is abundant. It can start from small phytoplankton to large whales. Here marine life is divided into coastal habitats and open water habitats. The coastal habitats range from the coastline of seawater and may go up to the continental shelf whereas the open water inhabitants live in the center of the sea or ocean.
Phytoplanktons produce almost half of the world’s oxygen and are the primary producers of the marine ecosystem.
Difference Between Ocean and Sea
Human uses of the Ocean Bodies
Ocean waters are one of the greatest resources known to mankind. It offers a very large supply of energy by means of the ocean waves, tides, salinity differences, and ocean temperature differences which have been in the recent decades actively harnessed to meet the growing energy needs. Offshore wind power is captured by wind turbines placed out on the ocean to generate electricity. It has the added advantage because wind speeds are higher in the oceans than on land, even though the cost of such offshore constructions can be very high in these wind farms. The ocean floors also have a huge deposit of conventional fuels like petroleum, crude oil, and natural gas, in rocky ocean floors.
Throughout history, these water bodies have served a wide variety of purposes, including navigation and exploration, naval warfare, travel, shipping and trade, food production (fishing, seaweed farming, and aquaculture), leisure (sailing, scuba diving, etc.), power generation and many more.
Threats to Marine Biodiversity
The greatest threat to marine life forms is from humans and unchecked human exploitation of marine resources. The constant buildup of unwanted foreign matter such as marine debris and microplastics, along with overfishing, ocean acidification, etc., have had adverse effects of climate change on oceans.
Marine Pollution
Marine pollution refers to the type of pollution in which substances used or discarded by humans, such as industrial, agricultural, and residential waste, particles, noise, excess carbon dioxide or invasive organisms enter the ocean waters by intentional dumping or accidental release and cause harmful effects there.
FAQs on Difference Between Sea and Ocean
1. How do We Define a Sea Differently from an Ocean? Explain with Examples.
On a geographical scale, seas are smaller water bodies than the mighty oceans. Even though sometimes used interchangeably, the terms “sea” and “ocean” are not the same. Both possess a great expanse of salty water in them, but seas are comparatively less dense saltwater bodies and are often partly enclosed by land. Water from different seas combines into the vast oceans, which make up 70% of the Earth's surface.
2. Does Water from Different Oceans Mix, like Water in Other Bodies? If not, Why so?
It is an interesting fact to know that the waters of some oceans (the Pacific and Atlantic oceans in this case) do not readily mix (that is they are immiscible). This is accounted for by the difference in the salinity level creating a sort of halocline (i.e. a rapidly changing salinity in the ocean with the depth of a water column). Although contrary to the misconception, this might not be the case for all oceanic bodies.
3. Give a Brief Account of the Oceanic Habitat and the Animal and Plant Diversity found in Oceans.
It is a well-established fact today that the first life forms evolved through abiogenesis within the oceans. Ever since the marine diversity of these water bodies has greatly expanded. It consists of various plants, animals, prokaryotes, etc. Of these, many of the members of the animal kingdom such as cnidarians, sponges, etc. are exclusive to the brackish and saltwater of the oceans. Even in the great depths of the ocean, where life seems impossible to exist, the deep sea and ocean fishes inhabit the ocean floor. From the gregariously growing phytoplanktons to the largest animal on the Earth, the blue whale, oceans support more than half of the life forms found on Earth.
4. What is the Role of Oceans in the World Ecosystem (Biosphere)?
The oceans play a vital role in the world ecosystem as it is closely associated with many biochemical cycles and phenomena of the Earth. These produce half of all the atmospheric oxygen available to living beings. This is because of the phytoplankton growing in the photic zone of the ocean; which absorbs a significant amount of carbon dioxide and releases oxygen during photosynthesis. By absorbing carbon dioxide (acting as a carbon sink), the oceans play a key role in controlling Earth’s climate. However, the oceans are also the most exploited part of the ecosystem. Since oceans absorb carbon faster than land plants, there is a greater risk of ocean acidification and a negative impact on marine life. To know more download the Vedantu app!
5. How is Seawater made Potable in the Current Times? Explain in Brief.
Mankind has recently made many innovations in the field of science and technology, especially to combat the scarcity of fresh water in many regions of the world. We know that saline water is not potable (cannot be used for drinking purposes). But with the use of the principle of reverse osmosis, saline water can be converted to fresh drinking water. For this purpose, large filtering devices called the Inflatable Solar still, etc., are employed in sea waters which work through thermal distillation and membrane separation to meet the growing demands for potable water.
