Ocean Habitats
Think of the ocean as a huge community
that includes living and nonliving things. The
ocean is divided into several zones. Ocean zones
include the intertidal zone, the neritic zone or
near shore, and the open-ocean zone. At the
highest high tide line on land, the intertidal zone
begins. From there, the zone stretches out to the
point on the continental shelf exposed by the
lowest low tide. The neritic zone extends from the
low-tide line out to the edge of the continental shelf. Beyond the edge of the
continental shelf lies the open ocean zone. This zone includes the surface zone, the
transition zone or thermocline and the deep ocean zone which is the deepest,
darkest part of the ocean. Here the temperature is very cold and the water pressure
is very high.
Intertidal Zone
The intertidal zone is
the shoreline area that falls
between the high tidemark
and the low tide mark. The
shore may be either a rocky
or a sandy shore. The area
right above the high tide
mark is also called the spray
zone, where pounding waves
spray the organisms
attached to the sides of
rocks. It can become flooded
during storms. Both areas
require the organisms living there to be able to adapt to extremes in their
environment regarding changes in salinity, water temperature, light, dissolved
gases, nutrients, wave action, and exposure to air. Organisms that live in the rocky
intertidal zone must be able to tolerate the pounding of the waves and withstand
periods of being underwater and periods of being exposed to the air. Animals in this
zone have structures that enable them to hold onto rocks and that keep their bodies
from drying out. They must also now have to hide from predators. Some examples
of are starfish with suction cups, barnacles which hold on to rocks and close tight
with water inside, sea urchin which buries itself.
Included in this zone are tide pools-which are depressions in the rock where
water remains during a low tide. Here the water can become warm and saltier by
evaporation, or it can be diluted by rain. Organisms, such as sea stars, mussels,
barnacles, and sea urchins, must be able to withstand the returning waves.
The Neritic Zone and Open Ocean
The neritic zone (also called near shore) is the part of the ocean that extends
from the low-tide line out to the edge of the continental shelf. The shallow water over
the continental shelf receives sunlight and a steady supply of nutrients washed from
the land into the ocean. The light and nutrients enable large, plantlike algae to grow.
Also, upwelling currents in many parts of the neritic zone bring more nutrients from the
ocean floor to the surface. Two habitats found in the neritic zone are coral reefs and
kelp forests.
Coral reefs can form only in shallow, tropical ocean waters. The reefs are formed
by groups of tiny coral animals that produce a
hard material around their soft bodies. When
the animals die, the hard material is left behind.
Over time, the animals' remains create a coral
reef. Coral reefs can be damaged easily and
do not recover quickly.
Coral reefs prefer warm waters.
Kelp forests grow up to 30 centimeters
per day in cold neritic waters where the
ocean has a rocky floor and can get as tall as
10 meters (33 ft). They are located in colder
waters like the California coast. Kelp are
large brown seaweed that attach to the sea
Kelp Forest are in colder water.
floor on the continental shelf and extend to
the surface. They are considered algae. Sea urchins and their main predator, sea
otters, are abundant in kelp forests. A variety of fish, sea cucumbers, turtles, sea stars
sea anemones, and abalones, also live in kelp forests.
The open ocean, or oceanic zone, begins where the neritic zone ends, at the edge
of the continental shelf. The open ocean differs from the neritic zone in two important
ways. First, only a small part of the open ocean receives sunlight. Second, the water
has fewer nutrients. As a result, the open ocean supports fewer organisms.
The surface zone is the only part of the open ocean that receives enough sunlight to
support the growth of algae. Microscopic algae (phytoplankton) are the base of food
webs in the open ocean. The algae are eaten by animal plankton (zooplankton) which in
turn are eaten by many other animals.
The open ocean's deep zone is dark and cold,
and fewer organisms live there.
Many deep-sea fishes produce their own light to
help them find food. The production of light by
living things is called bioluminescence. Located
in the deep zone are unusual habitats called
hydrothermal vents. A hydrothermal vent is an
area in which heated ocean water rises through
cracks in the ocean floor. The chemical nutrients
in the heated water support the unique group of organisms that are found around
hydrothermal vents. Here bacteria use the chemicals and the heated water to produce
food for themselves. They, in turn are
eaten by consumers like tube worms
which are eaten by other heterotrophs, like
giant clams, and so on. Thus, the
autotrophs in the deep ocean use the
process of chemosynthesis since there is
no light for photosynthesis and the
autotrophs of the surface zone are algae,
or phytoplankton.
Hydrothermal vent-black smoker
Besides hydrothermal vents, bacteria are also able to perform photosynthesis at cold
seeps. Cold seeps are places on the seafloor where cold hydrocarbon-rich water escapes.
The base of this community is chemosynthetic bacteria that use the methane
and hydrogen sulfide present in the seep water as an energy source in the same way they
do at hydrothermal vents..
A cold seep
Name__________________________________
Ocean Habitats
1. Name three ocean zones. ____________________, ________________, and _______________________.
2. What three zones does the oceanic zone contain? _________________, ________________, and the
________________ zones.
3. The part of the ocean that extends from the highest high tide on land to lowest low tide on the continental
shelf is called the__________________________ zone.
4. The intertidal zone can be a _____________ ________ or __________.
5. Animals living in the intertidal zones need to be able to adapt to extremes in their environments.
Name some of the conditions they must be able to endure. (This is important!)
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
6. What are depressions in the rock where water remains during a low tide? ____________________
7. True or False? The water in a tidal pool is the same as in the ocean.
8. The part of the ocean that extends from the highest low-tide line out to the edge of the continental shelf
is called the_________________ zone or ______________________.
9. True or False? The neritic zone receives very little sunlight.
10. What occurs in this zone that brings many nutrients to the surface? ___________________
11. What two habitats can be found here? _____________________ and ____________________
12. Which habitat is found in warm waters? ___________________
13. Coral reefs are made from ____________________________________________
14. Kelp are _____________________ and can grow up to _______________ tall.
15. Circle the letter of each sentence that helps explain why there is so much life in the neritic zone.
a. The water is shallow.
c. The water is high in nutrients.
b. Large, plantlike algae grow there.
d. Upwelling never occurs there.
16. Circle the letter of each sentence that is true about kelp.
a. They are algae.
b. They produce their own food.
c. They provide food for sea otters
d. They are found in warm climates.
17. The part of the ocean that extends beyond the edge of the continental shelf is called
the _________________ or _________________ zone.
18. True or False? The open ocean supports fewer organisms than the neritic zone.
19. True or False? The surface zone is the only part of the open ocean that receives enough
sunlight to support the growth of algae.
20. What is the base of the food web in the open ocean? _____________________________
21. Many organisms in the deep ocean are able to produce their own light. The production of light
by living things is called ____________________________________.
22 Because there is no sunlight to perform photosynthesis, what process is used instead?
____________________________________.
23. Who are the producers, or autotrophs of the deep ocean? _______________________
24. Name two places they are able to perform chemosynthesis. ____________________________ and
___________________________.
25. An area in which heated ocean water rises through cracks in the ocean floor is a(n)
____________________________________.
26. What are places on the ocean floor where minerals like seep out? _________________
27. Draw the 3 ocean zones and what is in them. (Neritic zone can be in either a cold or warm climate.)
land