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Chapter 14 – Ocean ZonesChapter 14 – Ocean Zones
Exploring the OceanExploring the Ocean
Exploring the OceanExploring the Ocean
• Because of the darkness, cold, and extreme pressure, scientists have had to develop new technology to enable them to study the deep ocean floor.
Exploring the OceanExploring the Ocean• A major advance in ocean floor
mapping was the invention of SONAR.
• It is a system that uses sound waves to calculate the distance to an object.
• SONAR stands for:
SOund NAvigation Ranging
Exploring the OceanExploring the Ocean
• The sonar system on
a ship sends out
pulses of sound that
bounce off the ocean floor.
• The equipment then measures how quickly the sound waves return to the ship.
Exploring the OceanExploring the Ocean
• Sound waves return quickly if the ocean floor is close.
• Sound waves take longer to return if the ocean floor is farther away.
Features of the Ocean FloorFeatures of the Ocean Floor
• The continental shelf is a gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent.
• Its width ranges from a few kilometers to 1,300 km from shore.
Features of the Ocean FloorFeatures of the Ocean Floor
• The continental slope marks the true edge of a continent.
• It is where the rock that makes up the continent stops and the rock of the ocean floor begins.
Features of the Ocean FloorFeatures of the Ocean Floor
• A seamount is a mountain whose peak does not break the surface.
Features of the Ocean FloorFeatures of the Ocean Floor
• The abyssal plain is a smooth, flat region.
• It is covered with thick layers of sediment, formed by the sunken remains of dead organisms from the surface.
Features of the Ocean FloorFeatures of the Ocean Floor
• The mid-ocean ridge is a continuous range of mountains that winds around Earth.
• It is almost 80,000 kilometers long.
Features of the Ocean FloorFeatures of the Ocean Floor
• On the other side of the mid-ocean ridge is a deep ocean trench.
Life at the Ocean’s EdgeLife at the Ocean’s Edge
Living ConditionsLiving Conditions• Some physical factors determine
where marine organisms can live include:
1. Salinity2. Water temperature3. Light4. Dissolved gases5. Nutrients6. Wave action
Living ConditionsLiving Conditions
• Scientists classify marine organisms according to where they live and how they move.
Living ConditionsLiving Conditions
• Plankton are tiny algae and animals that float in the water and are carried by waves and currents.
Living ConditionsLiving Conditions
• Nekton are free-swimming animals that can move throughout the water column.
• Examples:
– Octopus, squid, most fish, whales, dolphins, etc.
Living ConditionsLiving Conditions
• Benthos are organisms that inhabit the ocean floor.
• Example:
–Crabs, starfish, lobsters, sponges, anemones.
The Rocky ShoreThe Rocky Shore
• The intertidal zone stretches from the highest high-tide line on land out to the point on the continental shelf exposed by the lowest low-tide.
The Rocky ShoreThe Rocky Shore
• Organisms that live in the rocky intertidal zone must be able to tolerate:1. Wave Action
2. Changes in salinity
3. Temperature
4. Being exposed to both air and under water
The Rocky ShoreThe Rocky Shore
The Rocky ShoreThe Rocky Shore
• When the tide goes out some of the water remains in depressions among the rocks called tide pools.
• As the water in the tide pool is warmed by the sun it begins to evaporate causing the remaining water to become saltier.
Where River Meets OceanWhere River Meets Ocean
• Brackish water is salty sea water that has been mixed with freshwater.
• Estuaries are coastal inlets or bays where freshwater from rivers mixes with salty ocean water.
Where River Meets OceanWhere River Meets Ocean
• Along the United States coasts, most coastal wetlands are either salt marshes or mangrove forests.
Where River Meets OceanWhere River Meets Ocean• A salt marsh oozes with smelly mud that
is rich in nutrients.
• Mosquitoes swarm over the water, which moves slowly through the tall grasses.
• Cordgrass dominates the marsh.
• Tidal channels run through the Cordgrass (waves break up)
Where River Meets OceanWhere River Meets Ocean
• Mangrove forests grow well in brackish water.
• They provide a rich and sheltered area for organisms to grow.
• Fringe the coast of southern Florida.
The Neritic The Neritic & &
Open-OceanOpen-OceanZonesZones
What is the Neritic Zone?What is the Neritic Zone?
• The neritic zone is the part of the ocean that extends from the low tide line out to the edge of the continental shelf.
What is the Open-Ocean What is the Open-Ocean Zone?Zone?
• The open-ocean zone is beyond the continental shelf.
The Neritic ZoneThe Neritic Zone
• The neritic zone is home to the largest variety of organisms found in the ocean.
• Most of the world’s major fishing grounds are located in the neritic zone.
The Neritic ZoneThe Neritic Zone
• Why is the neritic zone home to so many living things?
– Shallow water receives lots of sunlight.
– Steady supply of nutrients from the land.
The Neritic ZoneThe Neritic Zone
• The light and nutrients allow giant algae (kelp) to grow.
• The algae serve as a food source and shelter for other organisms.
The Neritic ZoneThe Neritic Zone
• The neritic zone has two habitats:
1. Kelp forests
2. Coral reefs
Neritic Zone: Kelp ForestNeritic Zone: Kelp Forest
• Kelp is a large, heavy algae.
Neritic Zone: Kelp ForestNeritic Zone: Kelp Forest
• Kelp requires a solid, rocky bottom to anchor their stalks.
• A bundle of rootlike strands called a holdfast attaches the algae to the rocks.
Neritic Zone: Kelp ForestNeritic Zone: Kelp Forest
• The kelp use sunlight and dissolved gases in the neritic zone to produce their own food.
• Large collections of growing kelp is called a kelp forest.
• Kelp forests grow along the Pacific Coast from Alaska to Mexico.
Neritic Zone: Coral ReefsNeritic Zone: Coral Reefs
• Coral reefs are made of lots of tiny coral animals, not much larger than the size of a pencil eraser.
Neritic Zone: Coral ReefsNeritic Zone: Coral Reefs
• Coral animals produce a hard structure that surrounds their soft bodies.
• After the coral animal dies, the empty structure remains.
• New coral animals attach and grow on top of it.
Neritic Zone: Coral ReefsNeritic Zone: Coral Reefs
• Most of the coral reefs that exist today were begun about 5,000 to 10,000 years ago.
• Coral animals feed on algae that live with the reef.
• Coral reefs only grow in tropical, shallow waters.
Neritic Zone: Coral ReefNeritic Zone: Coral Reef
• In areas where the seafloor is sinking, a reef may develop over time into an atoll.
• An atoll is a ring-shaped reef surrounding a shallow lagoon.
Neritic Zone: Coral ReefsNeritic Zone: Coral Reefs
• Coral reefs protect the coastline from violent storms and erosion.
Neritic Zone: Coral ReefsNeritic Zone: Coral Reefs
• Coral reefs can be damaged:
– Touching the coral
– Breaking pieces off
– Changes in water temperature
– Changes in clarity
• Can be a major problem as reefs only grow a few centimeters a year.
The Open-Ocean ZoneThe Open-Ocean Zone
• Light from the sun only penetrates to a depth of less than 200 meters.
• Differs from the neritic zone:– small portion receives sunlight– Fewer dissolved nutrients
• Supports fewer organisms
The Open-Ocean ZoneThe Open-Ocean Zone
• The open-ocean zone is divided into parts:
1. The surface zone
2. The deep zone
The Open-Ocean Zone: The Open-Ocean Zone: The Surface ZoneThe Surface Zone
• The surface zone extends as far as sunlight reaches below the surface.
• The surface zone is the only part of the open-ocean zone that receives enough sunlight to support the growth of algae.
The Open-Ocean Zone: The Open-Ocean Zone: The Deep ZoneThe Deep Zone
• Few organisms live in the deep ocean due the very cold temperatures and great amounts of pressure.
The Open-Ocean Zone: The Open-Ocean Zone: The Deep ZoneThe Deep Zone
• Many deep sea organisms produce their own light which is called bioluminescence.
• This allows them to find food in the dark.
The Open-Ocean Zone: The Open-Ocean Zone: The Deep ZoneThe Deep Zone
• A hydrothermal vent is an area where ocean water sinks through cracks in the ocean floor, is heated by the underlying magma, and rises again through the crack.
The Open-Ocean Zone: The Open-Ocean Zone: The Deep ZoneThe Deep Zone
• Many of the deep sea creatures live around hydrothermal vents.
• The chemical nutrients in the heated water support the unique group of organisms that are found in around a hydrothermal vent.