introduction to the oceans

how the oceans formed

When Earth formed 4.6 billion years ago, it would not have been called the water planet. There were no oceans then. In fact, there was no liquid water at all. Early Earth was too hot for liquid water to exist. Earths early years were spent as molten rock and metal.

ancient oceans

Earths crust consists of many tectonic plates that move over time. Due to plate tectonics, the continents changed their shapes and positions during Earth history. As the continents changed, so did the oceans. About 250 million years ago, there was one huge land mass known as Pangaea. There was also one huge ocean called Panthalassa. You can see it in Figure 14.2. By 180 million years ago, Pangaea began to break up. The continents started to drift apart. They slowly moved to where they are today. The movement of the continents caused Panthalassa to break into smaller oceans. These oceans are now known as the Pacific, Atlantic, Indian, and Arctic Oceans. The waters of all the oceans are connected.

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water on early earth

Over time, Earth cooled. The surface hardened to become solid rock. Volcanic eruptions, like the one in Figure 14.1, brought lava and gases to the surface. One of the gases was water vapor. More water vapor came from asteroids and comets that crashed into Earth. As Earth cooled still more, the water vapor condensed to make Earths first liquid water. At last, the oceans could start to form.

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zones based on distance from shore

There are three main ocean zones based on distance from shore. They are the intertidal zone, neritic zone, and oceanic zone. Distance from shore influences how many nutrients are in the water. Why? Most nutrients are washed into ocean water from land. Therefore, water closer to shore tends to have more nutrients. Living things need nutrients. So distance from shore also influences how many organisms live in the water.

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zones based on depth of water

Two main zones based on depth of water are the photic zone and aphotic zone. The photic zone is the top 200 meters of water. The aphotic zone is water deeper than 200 meters. The deeper you go, the darker the water gets. Thats because sunlight cannot penetrate very far under water. Sunlight is needed for photosynthesis. So the depth of water determines whether photosynthesis is possible. There is enough sunlight for photosynthesis only in the photic zone. Water also gets colder as you go deeper. The weight of the water pressing down from above increases as well. At great depths, life becomes very difficult. The pressure is so great that only specially adapted creatures can live there.

how salty is ocean water

Have you ever gone swimming in the ocean? If you have, then you probably tasted the salts in the water. By mass, salts make up about 3.5 percent of ocean water. Figure 14.5 shows the most common minerals in ocean water. The main components are sodium and chloride. Together they form the salt known as sodium chloride. You may know the compound as table salt or the mineral halite. The amount of salts in ocean water varies from place to place. For example, near the mouth of a river, ocean water may be less salty. Thats because river water contains less salt than ocean water. Where the ocean is warm, the water may be more salty. Can you explain why? (Hint: More water evaporates when the water is warm.)

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ocean zones

In addition to the amount of salts, other conditions in ocean water vary from place to place. One is the amount of nutrients in the water. Another is the amount of sunlight that reaches the water. These conditions depend mainly on two factors: distance from shore and depth of water. Oceans are divided into zones based on these two factors. The ocean floor makes up another zone. Figure 14.6 shows all the ocean zones.

makeup of ocean water

You know that ocean water is salty. But do you know why? How salty is it?

why is ocean water salty

Ocean water is salty because water dissolves minerals out of rocks. This happens whenever water flows over or through rocks. Much of this water and its minerals flow in rivers that end up in the oceans. Minerals dissolved in water form salts. When the water evaporates, it leaves the salts behind. As a result, ocean water is much saltier than other water on Earth.

oceans and climate

Coastal areas have a milder climate than inland areas. They are warmer in the winter and cooler in the summer. Thats because land near an ocean is influenced by the temperature of the oceans. The temperature of ocean water is moderate and stable. Why? There are two major reasons: 1. Water is much slower to warm up and cool down than land. As a result, oceans never get as hot or as cold as land. 2. Water flows through all the worlds oceans. Warm water from the equator mixes with cold water from the poles. The mixing of warm and cold water makes the water temperature moderate. Even inland temperatures are milder because of oceans. Without oceans, there would be much bigger temperature swings all over Earth. Temperatures might plunge hundreds of degrees below freezing in the winter. In the summer, lakes and seas might boil! Life as we know it could not exist on Earth without the oceans.

oceans and living things

The oceans provide a home to many living things. In fact, a greater number of organisms lives in the oceans than on land. Coral reefs, like the one in Figure 14.4, have more diversity of life forms than almost anywhere else on Earth.

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the oceans influence

Oceans cover more than 70 percent of Earths surface and hold 97 percent of its surface water. Its no surprise that the oceans have a big influence on the planet. The oceans affect the atmosphere, climate, and living things.

oceans and the atmosphere

Oceans are the major source of water vapor in the atmosphere. Sunlight heats water near the sea surface, as shown in Figure 14.3. As the water warms, some of it evaporates. The water vapor rises into the air, where it may form clouds and precipitation. Precipitation provides the freshwater needed by plants and other living things. Ocean water also absorbs gases from the atmosphere. The most important are oxygen and carbon dioxide. Oxygen is needed by living things in the oceans. Much of the carbon dioxide sinks to the bottom of the seas. Carbon dioxide is a major cause of global warming. By absorbing carbon dioxide, the oceans help control global warming.

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instructional diagrams

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This diagram represents the layers of the ocean. The oceans are divided into two broad realms; the pelagic and the benthic. Pelagic refers to the open water in which swimming and floating organisms live. Organisms living there are called the pelagos. From the shallowest to the deepest, biologists divide the pelagic into the epipelagic the mesopelagic the bathypelagic the abyssopelagic and the deepest, the hadopelagic. The last three zones have no sunlight at all. The Habitat zone is formed by 5 mini zones: Abbysal, Bathyal, Hadal, Neritic, and Oceanic. One-third of the Earth is made up of the Abbysal zone. It is very cold and dark in this zone. In the Bathyal zone, the food and temperature easily fall into the deepest zones of the ocean. The Hadal zone is the deepest zone in the ocean. It has high-pressure conditions and it's really cold. The Neritic zone is rich in plants, animals, and nutrients that are carried by currents of land. In the Oceanic zone, there is an abundant life of plankton.

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This diagram shows the ocean floor. Like land terrains, the ocean floor also has ridges, valleys, plains and volcanoes. The seabed (also known as the seafloor, sea floor, or ocean floor) is the bottom of the ocean. The oceanic zone begins in the area off shore where the water measures 200 meters (656 feet) deep or deeper. It is the region of open sea beyond the edge of the continental shelf and includes 65% of the ocean's completely open water. The photic zone or sunlight zone is the depth of the water in a lake or ocean that is exposed to such intensity of sunlight which designates compensation point. The aphotic zone is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1% of sunlight penetrates. The abyssal zone is the layer of the pelagic zone of the ocean. At depths of 4,000 to 6,000 metres (13,123 to 19,685 feet), this zone remains in perpetual darkness and never receives daylight. The continental shelf is the area of the seabed around a large landmass where the sea is relatively shallow compared with the open ocean. This is geologically part of the continental crust. Studying the ocean floor is difficult because the environment is so hostile but scientists have discovered good ways to study the ocean floor through the years. Some ways are by using a sonar and special vehicles (some of which can even be done remotely).

questions

Sources of water vapor in Earths very early atmosphere included

-->  a. volcanic eruptions.

b. precipitation.

c. the oceans.

d. the moon.

What percent of the Earth is covered in salt water oceans?

a. 82%

-->  b. 71%

c. 65%

d. 49%

Gases the oceans exchange with the atmosphere include

a. oxygen.

b. carbon dioxide.

c. water vapor.

-->  d. all of the above

Coastal areas have a milder climate than inland areas because

a. water does not change temperature as rapidly as land

b. currents move warm and cold water around

c. breezes blow between land and sea

-->  d. all of these

Ocean water everywhere has a relatively moderate temperature because

-->  a. water flows throughout all the worlds oceans.

b. water warms up and cools down more quickly than land.

c. landmasses protect the oceans from temperature changes.

d. all of the above

Compared with shallow water, deeper water is

-->  a. saltier and colder

b. saltier and warmer

c. less salty and colder

d. less salty and warmer

Salt in the oceans comes from

a. deep-sea hydrothermal vents

b. near shore salt deposits

-->  c. river inflow

d. mid-ocean ridges

Some ocean zones are based on

a. distance from the equator.

-->  b. depth of water.

c. longitude.

d. two of the above

Which ocean zone receives a lot of sunlight and nutrients?

a. oceanic zone

b. aphotic zone

-->  c. neritic zone

d. benthic zone

The ocean zone that is always covered by water, but is fairly shallow in depth is the

-->  a. intertidal zone

b. oceanic zone

c. photic zone

d. neritic zone

Earths present oceans include the

a. Antarctic Ocean.

b. Tethys Ocean.

c. Indian Ocean.

-->  d. two of the above

Most nutrients enter ocean water from the

-->  a. land.

b. ocean floor.

c. aphotic zone.

d. atmosphere.

The oceans influence Earths atmosphere.

-->  a. true

b. false

Fewer organisms live in the oceans than on the land.

a. true

-->  b. false

Early Earth was too cold for liquid water to exist.

a. true

-->  b. false

The Dead Sea is extremely saline due to high evaporation.

-->  a. true

b. false

Oceans cover more than 70 percent of Earths surface.

-->  a. true

b. false

Earths oceans have always had the same configuration.

a. true

-->  b. false

Coastal areas always have colder climates than inland areas.

a. true

-->  b. false

Ocean water is saltier than any other water on Earths surface.

-->  a. true

b. false

Most nutrients in the ocean are washed in from the land.

-->  a. true

b. false

The amount of salt in ocean water is the same everywhere on Earth.

a. true

-->  b. false

About 250 million years ago, there was one world ocean known as Pansea.

a. true

-->  b. false

The climate of inland areas is affected by oceans.

-->  a. true

b. false

The water may be very deep in the neritic zone.

a. true

-->  b. false

Nutrients may be scarce in the oceanic zone.

-->  a. true

b. false

Temperature and pressure increase as you go deeper below the oceans surface.

a. true

-->  b. false

ocean zone that is closest to shore

a. aphotic zone

b. benthic zone

-->  c. intertidal zone

d. neritic zone

e. oceanic zone

f. sodium chloride

g. carbon dioxide

dissolved gas in ocean water

a. aphotic zone

b. benthic zone

c. intertidal zone

d. neritic zone

e. oceanic zone

f. sodium chloride

-->  g. carbon dioxide

open ocean beyond the continental shelf

a. aphotic zone

b. benthic zone

c. intertidal zone

d. neritic zone

-->  e. oceanic zone

f. sodium chloride

g. carbon dioxide

ocean zone on the ocean floor

a. aphotic zone

-->  b. benthic zone

c. intertidal zone

d. neritic zone

e. oceanic zone

f. sodium chloride

g. carbon dioxide

ocean zone where sunlight does not reach

-->  a. aphotic zone

b. benthic zone

c. intertidal zone

d. neritic zone

e. oceanic zone

f. sodium chloride

g. carbon dioxide

main salt in ocean water

a. aphotic zone

b. benthic zone

c. intertidal zone

d. neritic zone

e. oceanic zone

-->  f. sodium chloride

g. carbon dioxide

ocean zone that lies over the continental shelf

a. aphotic zone

b. benthic zone

c. intertidal zone

-->  d. neritic zone

e. oceanic zone

f. sodium chloride

g. carbon dioxide

diagram questions

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Identify the abyssal zone in this picture

a. R

-->  b. T

c. A

d. Y

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In the following diagram which label refers to the ocean's photic zone?

a. Y

b. J

-->  c. C

d. X

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Identify the photic zone in the following image:

a. X

-->  b. C

c. A

d. Y

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Where's the Benthic zone?

a. Y

b. C

c. A

-->  d. X

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Which label refers to high water?

-->  a. C

b. V

c. P

d. Y

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Which letter represents Abyssalpelagic?

-->  a. J

b. E

c. S

d. K

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Which label shows Bathypelagic?

a. C

b. H

-->  c. A

d. F

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Which Letter represent the Aphotic Zone?

-->  a. T

b. J

c. R

d. X

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Which letter represents the Pelagic Zone?

a. R

-->  b. J

c. X

d. T

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Where is the continental rise?

a. C

-->  b. Y

c. D

d. M

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Which letter represents the Aphotic Zone?

a. H

-->  b. A

c. D

d. U

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Which label shows the Mid-Water zone?

a. L

-->  b. D

c. K

d. U

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Which letter represents pelagic?

a. A

-->  b. L

c. D

d. U

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The Hadalpelagic Zone is also known as what?

a. The Twilight Zone

b. The Sunlight Zone

-->  c. The Trenches

d. The Abyss

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What is the area between 19,700 ft to 23,00 ft below sea level called?

-->  a. Ocean basin

b. Bathypelagic Zone

c. Hadalpelagic Zone

d. Abyssopelagic Zone

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What part of the ocean floor lies between the continental rise and the continental shelf?

-->  a. continental slope

b. ocean basin

c. hadalpelagic zone

d. bathypelagic zone

question_image

How many zones are there in the sea?

-->  a. 5

b. 4

c. 3

d. 6

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How many zones define the distinct major depth ranges for the earth's ocean floor?

a. 9

-->  b. 5

c. 4

d. 12

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What happens when humans dive at the abyssopelagic zone?

a. there will be increase in body temperature

b. nothing

-->  c. eardrums may be damaged due to high pressure

d. pressure will drop there

question_image

Which zone does the sunlight stop going through?

a. Mesopelagic

-->  b. Bathypelagic

c. Epipelagic

d. Abyssopelagic

question_image

Identify the part of the ocean floor nearest to the edges of continents.

-->  a. Continental shelf

b. Intertidal zone

c. Aphotic zone

d. Benthic zone

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What zone starts at 1000 meters down in the ocean?

a. Photic zone

b. Pelagic zone

-->  c. Aphotic zone

d. Continental shelf

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Which zone lies between the Intertidal zone and the Oceanic zone?

a. Photic zone

b. Abyssal zone

c. Pelagic zone

-->  d. Neritic zone

question_image

How many zones are there in the ocean?

a. 7

b. 10

c. 9

-->  d. 8

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What would be a good experimental method for mapping where the continental shelf ends and the benthic zone starts?

-->  a. Sonar

b. Seismic survey

c. Diving

d. Water sampling

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Which zone in the water receives sunlight?

a. benthic zone

b. aphotic zone

c. pelagic zone

-->  d. photic zone

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Which part of the pelagic zone extends from a depth of 200 to 1000 meters below the surface of the ocean?

a. Bathypelagic

b. Abyssalpelagic

c. Epipelagic

-->  d. Mesopelagic

question_image

What is the lowest layer of the ocean called?

-->  a. abyssalpelagic

b. mesopelagic

c. epipelagic

d. bathypelagic

question_image

What is the lowest level of the ocean?

a. muddy bottom

b. continental slope

c. continental shelf

-->  d. continental rise and deep ocean floor

question_image

Where are plants the best able to grow?

a. Near the ocean floor

b. Near the continental rise

-->  c. Near the continental shelf

d. Near the continental slope

question_image

What is the area between the continental shelf and the continental rise?

a. beach

b. neritic system

c. continental shelf

-->  d. continental slope

question_image

Up to what depth is light abundant for photosynthesis in the ocean?

a. 400 meters

-->  b. 200 meters

c. 300 meters

d. 500 meters

question_image

What is the area of seabed around a large landmass where the sea is relatively shallow compared with the open ocean?

-->  a. Continental Shelf

b. Oceanic System

c. Neritic System

d. Muddy Bottom

question_image

From the diagram, identify the zone that is found at a depth of 6000m to the bottom of the sea.

a. mesolelagic

-->  b. hadalpelagic

c. abyssalpelagic

d. bathypelagic

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How deep is the ocean in this diagram?

a. 1000 meters

b. 4000 meters

c. 200 meters

-->  d. More than 10,000 meters

question_image

How many meters down must you go to reach the Hadalpelagic division?

-->  a. 6000 meters.

b. 700 meters

c. 200 meters

d. 2000 meters

question_image

How many oceanic divisions are at least 2000m deep?

a. 1

-->  b. 2

c. 3

d. 4

question_image

This is the area that is not near the shore nor near the bottom.

a. Abyssal

b. Aphotic

-->  c. Pelagic

d. Littoral

question_image

What is the topmost layer of the ocean?

a. abyssalpelagic

b. mesopelagic

-->  c. epipelagic

d. bathypelagic

question_image

What zone represents the ocean surface?

a. Benthic zone

b. Abyssal zone

-->  c. Photic zone

d. Pelagic zone

question_image

How many oceanic zones are shown in the di5agram?

a. 4

b. 1

-->  c. 5

d. 3

question_image

How many zones are found in the diagram of the ocean floor?

a. 7

b. 8

-->  c. 5

d. 6

question_image

What is the portion of a lake or ocean where there is little or no sunlight?

a. Abyssal Zone

b. Photic Zone

-->  c. Aphotic Zone

d. Pelagic Zone

question_image

Which part is above 650 ft?

-->  a. Epipelagic

b. Abyssopelagic

c. Mesopelagic

d. Bathypelagic

question_image

What is between Mesopelagic and Abyssopelagic?

a. Epipelagic.

b. 200m or 650 ft.

-->  c. Bathypelagic.

d. Hadopelagic.

question_image

Which layer of the ocean is the most likely to be unexplored?

a. Epipelagic

b. Abyssopelagic

-->  c. Hadopelagic

d. Bathypelagic

question_image

How many pelagic zones are there?

-->  a. 5

b. 4

c. 3

d. 2

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What is the topmost layer of the ocean?

a. abyssopelagic

b. mesopelagic

c. bathypelagic

-->  d. epipelagic

question_image

What is the lowest zone of the ocean called?

a. Mid water zone

-->  b. Aphotic zone

c. Photic zone

d. Pelagic

question_image

How meters depth is the photic zone?

a. 1000m

b. 10000m

c. 500m

-->  d. 200m

question_image

Which is level of the ocean is located directly above the aphotic zone?

a. Photic zone

b. Pelagic

-->  c. Mid-water zone

d. Marianas trench

question_image

How many zones are there in the ocean depth as shown in diagram?

a. 4

b. 2

-->  c. 3

d. 5

question_image

Into how many zones is water under the ocean classified?

a. 4

b. 1

c. 2

-->  d. 3

question_image

Identify the photic zone

-->  a. U

b. A

c. D

d. L