Transcript Ocean Zones - Lower Dauphin School District

Chapter 5
Exploring the Ocean
People 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 Floor
sonar (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
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
the
Earth’s Layers
 The Earth consists of the following layers:
 the core – Earth’s center
 the mantle – the thick molten layer between the core
and the crust
 the crust – the thin,
rocky, outer layer of
Earth
Earth’s Plates
 plates – the pieces of Earth’s crust, along with parts
of the upper mantle
 Plate 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 Zones
 Ocean zones include:
 the intertidal zone

the highest high-tide line
on land
 the 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 Ocean
 Scientists 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
Webs
Food 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 Zone
Organisms 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 plantlike 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 Ocean
 Estuaries – 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 Forest
Kelp forests grow in somewhat
cold neritic waters where the
ocean has a rocky floor.clip
Conditions in the
Open Ocean
 The 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:
The Surface Zone (Sunlight)
2. The Transition Zone (Twilight)
3. The Deep Zone(Midnight)
1.

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 Ocean
 People 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 Resources
 Some nonliving ocean resources include:
 Water
 Fuels (oil)
 Minerals
 Nodules – black lumps
formed when metals
concentrate around pieces
of shell
Ocean Pollution
 Although 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