Ocean Depth Zones
Understand that the ocean has different zones depending on depth and light: the sunlight zone near the surface where most life lives, the twilight zone where light fades, and the midnight zone of total darkness
What a learner can do afterwards
- Name the three main ocean zones: sunlight, twilight, and midnight
- Explain that light decreases with depth until it disappears completely
- State that most ocean life is found in the sunlight zone because plants need light to grow
The lesson
You already know the ocean is full of many different animals living at many different depths. That is because the ocean is not just one big space. It has layers, like floors in a very tall building, but this building goes down instead of up. Each layer gets a different amount of sunlight.
Imagine a research submarine sinking straight down from the surface. At first, everything outside is bright and easy to see. That is the sunlight zone. Soon the water turns dim and blue. That is the twilight zone. Deeper still, it turns pitch black. That is the midnight zone, and the submarine needs its own lights to see anything at all.
Most ocean plants and animals live in the sunlight zone. Tiny floating plants in the water need light to grow, just like plants on land do. Since only the sunlight zone gets enough light, that is where the most life crowds together.
The ocean has three light zones, sunlight, twilight, and midnight, and life crowds near the top where the light is.
Watch it
Where it sits
Learn first
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.