Coral reefs are one of the richest ecosystems, or independent
environment on the earth, next to the tropical rain forest. Coral reefs are made
of billions of little animals called polyps. Reefs are made when the coral polyps
float around and attach to a solid surface. Then they take in food and make a
calcium carbonate skeleton that surrounds the polyps and protects them. There
are more than 1,000 species of hard or stony corals. A polyp is a hollow cylinder
shaped organism that is attached to a solid surface at the bottom of the polyp.
At the top of the polyp is the mouth which is surrounded by tentacles that gather
food. Inside the tentacles are stinging cells called nematocysts that paralyze
There are many different types of coral, and coral formations. One of the formations
is an atoll which is when there is an island circled by a coral reef and the island
sinks there is a circular ring of coral. Another is a barrier reef which runs
along the side of an island or land mass. The last is a fringing reef which is
an off shore reef that is not one reef, but many smaller sections of reefs.
There are two main types of corals, hard corals and soft corals. Hard corals are
formed when the polyps grow they form a calcium carbonate skeleton around them.
The skeleton helps protection from predators. Soft coral are formed by polyps
that grow into bigger forms of themselves.
Condylactis gigantea are a large
and colorful sea anemone. The tentacles can get up to 15 cm long, they are thick
tapering, tan, usually tipped with pink, purple or green bulbs. Condylactis
reproduce by budding. Budding is an asexual form of reproduction. It is when the
Condylactis make a smaller Condylactis that are attached to the
Condylactis gigantea are found in Florida and the Caribbean. Like other
Cnidarinas Condylactis have a stinging cells. Those stinging cells are
called nematocysts. They are not just used to ward off predators, but also to
catch prey. When the tentacles touch the prey the nematocyst shot out a pin like
barb that stabs into the prey and injects venom into it.
Zooxanthellae are a golden brown single celled organism. Zooxanthellae
live inside of most corals and Condylactis gigantea. The coral and the
zooxanthellae have a mutualistic relationship. This means that both the coral
and the zooxanthellae benefit. The zooxanthellae gain shelter and the coral or
Condylactis obtain nutrients. The zooxanthellae gives the Condylactis
food by the process of photosynthesis. The equation for photosynthesis is: CO2
+ H2O + light energy----> (CH2O)n +O2, which is carbon dioxide + water + light
energy ----> glucose + oxygen. So when carbon dioxide, water and light energy
are combined sugar and oxygen are produced.
The Condylactis and the zooxanthellae have a mutualistic
relationship. This means that both the Condylactis and the zooxanthellae
gain something. The zooxanthellae gain shelter and the Condylactis gain
food. There are other kinds of endosymbiotic relationships. One is a parasitism
relationship in which one organism benefits and the other one is harmed. In this
relationship the organism that benefits is a parasite. And the organism that is
harmed is the host. A parasite is an organism that lives off another organism
which is the host. Another symbiotic relationship is a commensalism relationship
in which one organism benefits and the other is unaffected.
Photosynthesis is the base of the food chain in the ocean. Many
microorganisms are capable photosynthesis, and many other organisms rely on them.
The process for photosynthesis is: CO2 + H2O + light energy----> (CH2O)n +O2,
which is carbon dioxide + water + light energy ----> glucose + oxygen. So when
carbon dioxide water and light energy are combined sugar and oxygen are created.
Coral bleaching results from the loss of endosymbiants from an
endosymbiotic relationship. In this experiment the endosymbiants are represented
by the zooxanthellae. The endosymbiotic relationship in this experiment is a mutualistic
relationship between the Condylactis and the zooxanthellae. When the zooxanthellae
die, the Condylactis loses an important source of nutrients. When the Condylactis
lose the zooxanthellae they also lose their color, leaving nothing but the transparent
coral polyps allowing the white calcium carbonate skeleton to show through. If
the coral does not regain the zooxanthellae in time, or has had repeated bleaching,
it will end in the death of the coral. However it can live without the zooxanthellae
for little while, but it will not grow as fast.
When the coral die most of the organisms that depend on them will also die. Because
they would have lost an important source of food, and shelter. Even if the organisms
do not feed directly on the coral, it might eat things that eat directly on the
coral like, the butterfly fish, sea slugs, and some invertebrates. When the organisms
that feed directly on the coral coral die, the organisms that feed on them will
and, and the cycle will keep repeating itself.
Temperature as a Cause of Coral Bleaching
Scientist suspect many different causes for coral bleaching. One
is temperature, which is being investigated in this experiment. This has been
thought to be a problem sense El Nino, because many reefs started to bleach during
El Nino, which raised ocean temperatures above normal. The normal temperature
for Condylactis is 22 degrees C to 28 degrees C (71 degrees F to 82 degrees
F). If the temperature changes to quickly or for long periods of time the zooxanthellae
will die because it will not be able to adapt to the new temperature. If the ocean
temperatures took a longer time to change the zooxanthellae would have a better
chance at surviving.
When setting up the tank it is best to use crushed oyster shells
as a substrate. The Condylactis eat newly hatched brine shrimp. The oyster
shells buffer the pH. Also putting under gravel filters in the tank provides oxygen
which the zooxanthellae use to make sugar in the process of photosynthesis. The
specific gravity (salinity) of the water should be 1.024. If the specific gravity
is less than 1.024 add salt to the water. If it is more add fresh water to the
mixture. When using tap water it is necessary to use detoxifier (AmQuel) in the
water because it neutralizes the chlorine found in tape water. The tanks being
used in this experiment are ten gallon tanks. For every ten gallons of water put
5 ml of detoxifier in the water.
Back to Main Page