OCEAN ZONES• ZONES OF THE WATER COLUMN

• FEATURES OF THE OCEAN FLOOR• OCEAN BIOMES

Pelagic

Abyssal

Intertidal

Benthic

Four Zones of

Interest

ZONES OF THE WATER COLUMN

• Intertidal: the area between high tide and low tide. Sometimes covered, sometimes exposed, a very tough habitat to live in. Subjected to drying and submersion, temperature extremes, the pull of the waves, and sea and land predators. Animals often burrow or have hard shells that can be sealed to prevent water loss. Plants usually cling to hard bottoms.

Intertidal zone creatures

High Tide

Low Tide

Another view– zones in zones

Zones of the Water Column• Pelagic zone: Open ocean zone.

Usually sub-divided by depth or amount of sunlight. The upper pelagic receives sunlight, so there are many phytoplankton for photosynthesis. Zooplankton, jellyfish, squid, and fishes of all sizes make up the food chain. The lower reaches receive less or no sunlight, so there are no plants and animals are often bioluminescent (make their own light).

Pelagic Zone

Inhabitants of the Pelagic Zone

A Pelagic Food Web

BENTHIC PELAGIC

Zones of the Water Column• Abyssal: The midnight zone of the ocean–

no light penetrates. The pressure at 10,000 ft. would be like you having 5 jumbo airliners on your back. Animals are adapted to withstand the dark, the cold (near freezing), and the tremendous pressure. That’s why they usually don’t survive the trip to the surface. Most are dark or nearly transparent in color, and are bioluminescent. They don’t move much, and usually eat what falls from above. Jaws are big to swallow large objects whole.

Monsters of the Abyss

The Abyss

Increasing Cold Increasing Pressure

A very hostile environment

Fantastic Denizens of the Deep

ZONES OF THE WATER COLUMN• Benthic: a term meaning bottom, is the ocean

zone ranging from the deepest part of the ocean to the shore. Many kinds of organisms live in the benthic zone– plants, anemones, sponges, fish, skates and rays, octopus, mollusks, crabs, sea stars, corals and worms. Most are scavengers. In the deep ocean, there are special benthic communities around hydrothermal vents whose energy comes from chemical reactions rather than from the sun.

Benthic Zone– from the shore to the depths

BENTHIC PELAGIC

Intertidal Benthic Coral Reef

Hydrothermal vent

Hydrothermal Vents

In 1977, the submersible Alvin

found seafloor vents that were gushing hot mineral-rich water in the midnight depths of the ocean.

Cold sea water seeps into cracks in the Earth’s crust and is superheated by the magma in the mantle. The hot water with dissolved minerals from the magma rises and spews out like an undersea geyser .

Cold water and chemical reactions cause mineral deposits to settle out as vent chimneys.

Fantastic communities of organisms that live by chemosynthesis thrive around these “black smokers”, using energy from chemical reactions withminerals in the water to live.

OCEAN ZONES• ZONES OF THE WATER COLUMN

• FEATURES OF THE OCEAN FLOOR• OCEAN BIOMES

• What do you think the ocean floor looks like?

Is it flat? Saucer-shaped? Mountainous?

• The same mountains, valleys, plains, trenches, and pits we see on land are also on the ocean floor.

Features of the Ocean Floor

The tallest mountains, the deepest valleys, and the flattest plains on earth are all on the ocean floor!

Features of the Ocean Floor• Continental shelf: surrounds the continent as

a shallow extension of continental crust extending out to the continental slope.

• Continental slope: steep drop-off at the end of the continental shelf that connects the continental crust to the oceanic crust.

• Together, they make up the continental margin.

Features of the Ocean Crust• Abyssal plains: are the flattest areas on earth.

• Ocean ridges: are long mountain ranges formed when magma seeps or erupts between pieces of the Earth’s crust (tectonic plates).

• Trenches: are the deepest part of the ocean and are formed when one tectonic plate is forced under another tectonic plate.

• Seamounts: isolated volcanic mountains which erupt under the ocean. Large ones are islands.

• Guyots: are extinct volcanoes with eroded flat tops.

The highest mountain on Earth is Mauna Kea, Hawaii, a seamount

Ocean ridges form a mountain chain 40,000 miles long through all the oceans

The average depth of the ocean is 12,200 feet (3,720 m.)

Trenches form where tectonic plates (chunks of the Earth’s crust) are forced under another plate.

The Mariana Trench in the western Pacific is the deepest point on Earth– 36,198 ft. (11,033 m.)

Trieste and the Mariana Trench

In 1960, the US Navy sent a

small submersible (mini-sub)

to see how far down it

could go. It sat on the

bottom at 35,838 ft.

(10,923 m.) The sailors had

7 miles of water over their

heads!

OCEAN ZONES• ZONES OF THE WATER COLUMN

• FEATURES OF THE OCEAN FLOOR

• OCEAN BIOMES

Ocean Biomes• Can be divided by zones: intertidal,

pelagic, and abyssal. Benthic organisms are the bottom dwellers in each zone.

• Each zone requires different adaptations for survival. Organisms are specialized to live in a particular zone.

• Like in land biomes, similar types of flora and fauna live in similar types of biomes across the world oceans.

Intertidal

Pelagic

Abyssal Benthic

Other Aquatic Biomes• “Aquatic” means water.

• Other aquatic biomes besides the ocean (marine biome) are freshwater and estuarine.

• Freshwater is water with no salt, and includes rivers, lakes, ponds, etc.

• Estuaries are environments where salt water and fresh water meet. The salinity (amount of salt) varies with the tides and the seasons.

• Estuaries are often warm, shallow, protected places that serve as nurseries for marine organisms.

Marine

Freshwater

Estuary

For Help:

AMSTI-GLOBE The GLOBE Programwww.amsti.org/globe www.globe.gov

Judy Reeves Lynn VaughanAMSTI-GLOBE AMSTI-GLOBEResource Specialist Resource Specialistjudy@amsti.org lynn@amsti.org

Robin Nelson Jerry CobbsAMSTI-GLOBE AMSTI-GLOBEAdministrator Technology Specialistrobin@amsti.org jerry@amsti.org