Corals: Landlords of the Reefs
What should you know about corals? They are _________________________
_______________live inside of them (________________________________)
Two kinds: Soft corals and Hard corals (These build reefs!)
They are made of tiny __________ (which look like __________________________)
Hard Corals: The Reef Builders. Polyps build hard _____________________________
around their bases. The cups cement together to make a coral colony. Reefs are made of
hundreds of hard coral colonies next to and on top of each other.
What’s a Polyp? Tentacles release stinging cells when something brushes by them.
Polyps make their own limestone cup to hide in during the day.
At night, polyps come out to catch plankton floating by.
Inside polyps live zooxanthellae, which are _____________. Zooxanthellae give corals
their color. Since algae are plants, they use ______________________________ to make
food (the process known as photosynthesis).
Symbiosis: So Happy Together. ______________________________________________
is called symbiosis.
Zooxanthellae: __________________________________________________________
______________________________________________________________________.
Coral polyps protect the zooxanthellae, ______________________________________
______________________________________________________________________.
Reefs:
A prominent feature of _____________________________ marine settings is the reef.
Reefs are natural structures of rock formed by ______________________________.
Today’s reefs are largely made by corals, but in the geological past, have been
constructed by ____________________________________________________.
Reef-building organisms build skeletons of ___________________________________
in the form of ____________________________________________________.
Coral reefs are often called the “________________________________” due to the great
diversity of creatures that form them. Note that the brilliant colours apparent in corals are
from the microscopic algae in the coral tissues (different colours absorb different
wavelengths of light)
Conditions necessary for reef development
Large reefs are limited to the _________________ seawater areas of the _____________.
Calcium carbonate is easier to precipitate in warm water than in cold water.
Secretion of calcium carbonate is aided by microscopic cells of algae that live in the
tissues of reef builders (the algae remove carbon dioxide from the tissues, decreasing the
acidity of the water).
Reefs also tend to preferentially form in areas where:
1. Little _________________________________________________________
(such sediment particles smother reef builders).
2. Nutrient levels are _____________________.
3. Water is _______________________.
Reef builders are zoned in a reef according to their form (encrusting forms tend to
dominate the reef crest where wave action is strongest, while more delicate branching
forms are confined to deeper water zones where water action is more gentle)
A _________________________ can develop behind a reef, where it is protected from
strong waves
An atoll is a: ____________________________________________________________.
It is likely that Gilligan’s Island was set in a partially formed atoll.
An atoll is formed first as a reef that fringes a volcanic island.
As the island sinks (after volcanic activity has ceased and the crust has cooled, becoming
denser), the reef continues to build upward, eventually ending up as a ring-shaped
structure.
Great Barrier Reef Overview
Located in the Coral Sea on the coast of ______________________________________
Largest Reef System in the world consisting of __________ individual reefs surrounding
______________ islands. ____________________ km long with an area of 344,400 km2
Consists of ______________ species of hard and soft corals and supports 10 of thousands
of other species.
Reef Building Processes:
Reef formation begins with Fringing Reefs
Fringing Reefs generally form on: ___________________________________________,
but are inhibited by an influx of freshwater and river sediment.
Eventually enough reef is formed to become a barrier reef.