1. -Gautam Sanka

2. What is a Coral? Coral is an animal in the phylum Cnidaria and class Anthozoa Coral exists in the ocean as polyps which are a form of life in Cnidarians. Polyps are cylindrical and are attached to a substrate. They also have many tentacles extending outwards to gather food. Corals as Polyp

3. Then what are Coral Reefs? A coral reef is about a million of these individual coral polyp shells all stuck one on top of the other. As coral die, new coral builds up on top of dead shells These reefs are best suited for shallow, clear, warm waters Reefs are some of the most biodiverse places on earth. Coral Reef with many coral and fish as well

4. How do Coral Reefs Form? Coral Reefs form in tropical waters as these waters satisfy their specific conditions: Salinity between 34-37 ppt Temperature between 25 to 37 degrees C Lots of Sunlight that limits them to a depth of 40m Reefs have a cycle that they follow: Fringing Reef grow in shallow water that is connected to the shore Barrier Reef separated from a mainland or island shore by a deep lagoon Atoll circular or continuous barrier reef extending all the way around a lagoon without a central island

5. Darwin’s Structure and Distribution of Coral Reefs Lagoon

6. What are Zooxanthellae? Zooxanthellae are flagellate protozoa that are golden-brown They are autotrophs and need the sunlight to survive Zooxanthellae algae

7. Coral-Zooxanthellae Symbiosis Symbiosis is a relationship that benefits both the coral and the Zooxanthellae Inside the sac of each coral polyp the zooxanthella The algae gives off oxygen and other nutrients that the coral polyp needs to live and the polyp gives the algae CO2 and a home This partly the reason that Coral live in shallow waters- to have proper access to sunlight

8. Bleaching and Death Recent increases in ocean temperatures have caused much stress on coral reefs Coral bleaching occurs when the Zooxanthellae leave due to the stress on the ecosystem The algae gives the coral their color and without them, the white limestone shells show through. Other plants will come to replace the algae which usually leads to the Coral dying. This coral reef is undergoing massive coral bleaching

9. Youtube Video of Bleaching

10. Review Questions Is Coral an Animal or Plant? What Phylum does Coral belong to? What is one example of a symbiotic relationship with coral? Name the three types of reefs summarized by Darwin. What are some general conditions Corals must live in to survive? What is one human cause of Coral Bleaching?