Coral Reefs

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 prey.
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

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 "parent" organism.
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

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.

Culturing Condylactis

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.

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