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Ocean Zones/Floo
rChapter 5
Exploring the OceanPeople have studied the ocean since ancient times,
because the ocean provides food and serves as a route for trade and travel. Modern scientists have studied the characteristics of the ocean’s waters and the ocean floor. clip 1
Exploring the Ocean Floorsonar (SOund NAvigation and Ranging) – a major
advance in floor mapping which uses sound waves to calculate the distance to an object. clip 2
Features of the Ocean Floor If you could travel along the ocean floor, you would see:
the continental shelf gently sloping, shallow area of the ocean floor that extends outward from the edge of a
continent the continental slope
the steep edge of a continental shelf the abyssal plain
the smooth, nearly flat region of the ocean floor the mid-ocean ridge
a continuous range of mountains that winds around Earth
Trench a steep sided canyon in the ocean
floor
Seamount – a mountain on the ocean floor,
completely under water
Complete Diagram
Earth’s LayersThe Earth consists of the following layers:
the core – Earth’s centerthe mantle – the thick molten layer between the core
and the crustthe crust – the thin,
rocky, outer layer of Earth
Earth’s Platesplates – the pieces of Earth’s crust, along with parts
of the upper mantlePlate movements have shaped many of the most
dramatic features of Earth, both on land and under the ocean.
seafloor spreading – a process by which new rock is added to the ocean floor along the boundary between diverging plates (clip 3)
Seafloor spreading is slowly causing Earth’s plates to move together.
Seafloor Spreading
Ocean ZonesOcean zones include:
the intertidal zone the highest high-tide line
on landthe neritic zone
Extends from the low-tide line out to the edge of the continental shelf
the open-ocean zone the ocean beyond the edge of the continental shelf
Life in the OceanScientists classify marine organisms according to
where they live and how they move.Plankton – tiny algae and animals that float
in the water and are carried by waves and currents
Nekton – free-swimming animals that can move throughout the water column
Benthos – organisms that inhabit the ocean floor
Ocean Food WebsFood web – All of the
feeding relationships that exist in a habitat.
Note the importance of
Phytoplankton (algae)
and zooplankton
(microscopic animals) at
Its base.
Intertidal ZoneOrganisms that live in the shallow waters of the rocky
intertidal zone must be able to tolerate the constant pounding of the waves and changes in both salinity and temperature. They must also withstand periods of being underwater (wet) and periods of being exposed to the air. (dry) clip 4
Neritic Zone The somewhat shallow, warm water over the continental shelf
receives sunlight and a steady supply of nutrients washed from the land into the ocean. The light and nutrients enable large plant-like algae to grow. A large variety of plants and animals are found here. This zone houses the most life overall of all the zones.
Where River Meets OceanEstuaries – coastal inlets or bays where fresh water
from rivers mixes with the salty ocean water.Along the coasts of the United States, most
wetlands are either mangrove forests or salt marshes.
Mangrove forests are short, gnarled trees that grow well in brackish water.
Salt marshes consist of mud and cord-grass.
Coral Reef
A coral reef is another type of diverse habitat found in the neritic zone.
Coral reefs can form only in shallow, tropical ocean waters.
Life in a Kelp ForestKelp forests grow in somewhat
cold neritic waters where the ocean has a rocky floor.clip
Conditions in the Open OceanThe open ocean differs from the neritic zone in two
important ways. First, only a small part of the open ocean receives sunlight. Second, the water has fewer nutrients.
The three open ocean zones:1. The Surface Zone (Sunlight)
2. The Transition Zone (Twilight)
3. The Deep Zone(Midnight) Bioluminescence – the production of light by living things
Hydrothermal Vents Hydrothermal vents are places where ocean water
sinks through cracks in the ocean floor and is heated by the underlying magma. The heated water then rises again through the cracks. Water is filled with minerals.clip
Resources From the OceanPeople depend heavily on fishes and other ocean
organisms for food. Ocean organisms also provide materials that are used in products such as detergents and paints.
Aquaculture – the farming of saltwater and freshwater organisms
Nonliving ResourcesSome nonliving ocean resources include:WaterFuels (oil)Minerals
Nodules – black lumps formed when metals concentrate around pieces of shell
Ocean PollutionAlthough some ocean pollution is the result of
natural occurrences, most pollution is related to human activities.
It is important for humans to protect Earth’s oceans.clip
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