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