Chapter 14 Ocean Zones Exploring the Ocean Exploring

Chapter 14 – Ocean Zones

Exploring the Ocean

Exploring 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 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 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 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 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 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 Floor • A seamount is a mountain whose peak does not break the surface.

Features 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 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 Floor • On the other side of the mid-ocean ridge is a deep ocean trench.

Life at the Ocean’s Edge

Living Conditions • Some physical factors determine where marine organisms can live include: 1. 2. 3. 4. 5. 6. Salinity Water temperature Light Dissolved gases Nutrients Wave action

Living Conditions • Scientists classify marine organisms according to where they live and how they move.

Living Conditions • Plankton are tiny algae and animals that float in the water and are carried by waves and currents.

Living Conditions • Nekton are free-swimming animals that can move throughout the water column. • Examples: – Octopus, squid, most fish, whales, dolphins, etc.

Living Conditions • Benthos are organisms that inhabit the ocean floor. • Example: – Crabs, starfish, lobsters, sponges, anemones.

The 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 lowtide.

The 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 Shore

The 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 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 Ocean • Along the United States coasts, most coastal wetlands are either salt marshes or mangrove forests.

Where 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 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 & Open-Ocean Zones

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 Zone? • The open-ocean zone is beyond the continental shelf.

The 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 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 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 Zone • The neritic zone has two habitats: 1. Kelp forests 2. Coral reefs

Neritic Zone: Kelp Forest • Kelp is a large, heavy algae.

Neritic 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 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 Reefs • Coral reefs are made of lots of tiny coral animals, not much larger than the size of a pencil eraser.

Neritic 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 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 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 Reefs • Coral reefs protect the coastline from violent storms and erosion.

Neritic 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 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 Zone • The open-ocean zone is divided into parts: 1. The surface zone 2. The deep zone

The Open-Ocean Zone: The 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 Deep Zone • Few organisms live in the deep ocean due the very cold temperatures and great amounts of pressure.

The Open-Ocean Zone: The 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 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 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.