pg. _____ Date _____________________
Reflection: The Ocean Foldable
Directions: Use The Ocean Foldable to answer each question.
1. Where in the ocean do you think water pressure is greatest? Explain why.
Water pressure is greatest at the bottom of the ocean because water pressure increases with
depth (there is more water above you to push down on you).
2. How do currents distribute heat around the globe?
Currents move warm water away from the equator and cool water away from the poles.
3. What factor do you think would cause a surface current to change direction?
A surface current would change direction due to a change in the direction the wind is blowing.
4. Describe the similarities and differences between surface currents and waves.
Similarity: Both surface currents and waves are caused by wind.
Difference: Currents move water, but waves move energy (not water).
5. How does the surface (photic) zone of the open ocean differ from the deep zone (aphotic)?
The surface zone has enough sunlight for organisms to carry out photosynthesis (like plankton),
and there are more living things in this zone than in the aphotic zone. The aphotic zone is dark
and cold because little sunlight penetrates beyond the top 200 meters of the ocean’s surface.
6. How do the continental slope and the continental shelf differ?
The continental shelf is the part of the ocean floor nearest the edges of continents. It slopes
gradually and the water here is shallow. The continental slope is a steep slope with a sharp drop
to the ocean floor, and it lies between the continental shelf and the abyssal plain.
7. Why does warm water stay at the ocean surface?
Warm water stays at the ocean surface because it is less dense than cold water.
8. Describe the similarities and differences between surface currents and deep currents.
Both surface currents and deep currents are masses of moving water, and they both move heat
and nutrients from one part of the ocean to another.
Surface currents are caused by wind blowing over the ocean, and they extend no more than 200
meters (500 ft) below the ocean’s surface. Surface currents are affected by the Earth’s rotation
and the shape of the continents.
Deep currents are caused by changes in the density of water (due to a change in temperature,
salinity, or both). Because cold water is more dense than warm water, it will sink and warm
water will rise.
9. Describe the relationship between ocean temperature and depth.
As the depth of the ocean increases, the water temperature decreases. There is a gradual
decrease in the surface layer (which is the warmest layer), a sharp decrease in the thermocline
layer, and a gradual decrease in the deep water layer (this water approaches freezing).
10. Describe the similarities and differences between upwelling and downwelling.
Both upwelling and downwelling are examples of deep currents, so both involve moving water
driven by differences in density.
Upwelling is the movement of water up to the surface from the bottom. This process brings up
nutrients from the lower depths. Downwelling is when surface ocean water sinks to the bottom.
As the water sinks, it carries oxygen down from the surface.
11. How is the density of water related to its salinity?
The more salt dissolved in water the greater its density (more salt = greater density).
12. Why is there so little life at the bottom of the ocean?
The bottom of the ocean is dark, very cold, and has few nutrients for organisms to live off of.
13. Compare the neritic, intertidal, and oceanic zones.
Zone
Location
lies over the continental shelf
neritic
intertidal
oceanic
Characteristics
water is not very deep; receives
plenty of sunlight and nutrients;
many organisms live in this zone
closest to the shoreline
at high tide it is covered with water
and at low tide it is exposed to air;
receives the most sunlight and has
varied nutrients
open ocean out past the continental water may be very deep; has less
shelf
sunlight in its deeper parts and
nutrients are scarce as you get
deeper; fewer organisms live here