Exploring the Open Ocean: Zones and Life Forms, Study notes of Earth Sciences

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THE OPEN OCEAN

Grade 3 Unit 2 Lesson 1

The ocean is the world’s largest habitat.

It covers about 70% of the Earth’s surface.

The ocean floor is not flat; it has valleys (canyons) and

mountains (seamounts) just like those on land.

Use 3-D red/blue glasses to view this image.

Scientists divide the ocean into two zones:

benthic zone

pelagic zone

Photic Zone

Photic Zone is the top layer, nearest the surface of the ocean and is

also called the sunlight layer. In this zone enough light penetrates

the water to allow photosynthesis.

photic zone Disphotic Zone The Disphotic Zone is found just below the Photic Zone and is known as the twilight layer. In this zone only a small amount of light penetrates the water. Plants do not grow here due to the insufficient amount of light.

The whale shark, like most marine organisms, is typically found in the sunlight layer or photic zone of the open ocean layers.

Animals that live in the disphotic zone , like many types of squid, are adapted to life in near darkness, cold water, and high pressure.

Name That Open Ocean Zone!

Photic zone

(sunlight zone)

Name That Open Ocean Zone!

Aphotic zone

(darkness layer)

Name That Open Ocean Zone!

Photic zone

(sunlight zone)

Disphotic zone

(twilight layer)

Name That Open Ocean Zone! Nice work!

Aphotic zone

Photic zone

Disphotic zone