Coral reefs are formed by coral polyps, which are small marine invertebrates related to jellyfish and anemones. Coral polyps secrete calcium carbonate to build protective structures called coralites. Over time, the accumulation of coralites forms three types of reef structures: fringing reefs near shorelines, barrier reefs separated from shorelines by lagoons, and atolls surrounding central lagoons. Coral reefs provide habitat for many species but are threatened by rising water temperatures and pollution.

1. An Introduction to Coral Reefs

2. What is coral? It’s a living organism! It is an invertebrate 2 different types: Reef Building: Hermatypic Solitary: Ahermatypic Coral is cousins to jellyfish and anemones (Cnidarians) Today we will talk mainly about reef building coral Sun Coral Polyps

3. Where Can You Find Coral Reefs? Coral is found all over the world: Tropical Temperate Polar Only tropical corals build reefs Coral reefs around the world

4. Coral Builds Reefs? The animal portion of the reef is called a polyp The polyp absorbs calcium carbonate out of the water The calcium carbonate is used to build the reef

5. Reefs Corals Build Corals can build three types of reefs: Fringing: grows close to shore Barrier: also grows close to shore but has a lagoon separating it from the shore Atoll: a ring of coral that surrounds a lagoon, often grows on a submerged mountain or volcano http://www.nos.noaa.gov/education/kits/ corals/media/coral04a_240.jpg

6. Coral are Cnidarians Soft bodied Carnivorous Stinging tentacles arranged in a circle around their mouth Body symmetry Specialized tissues

7. Cnidarians Usually two life stages: Polyp Medusa Gastrovascular cavity Food is broken down here but digested intracellularly

8. Cnidarians Respiration and waste removal takes place through body walls Nerve net Some have a hydrostatic skeleton Some move through jet propulsion

9. Anatomy of Coral The coral polyps build a calcium carbonate cup called a corallite to live in Coral has stinging cells called nematocysts

10. Stinging Cells Nematocysts help coral catch food They also help protect the coral When the cell is stimulated, it releases a sharp barb The barb will fire and catch the food and bring it back towards the mouth

11. Coral and Zooxanthella Symbiotic relationship Zooxanthella is an algae that lives in the skin of coral Coral provides protection Zooxanthella provides food and color!

12. Coral is Picky Very specific habitats: Temperature: 73-75  F Depth: Less than 80 ft to 230 feet Salinity: Normal salt levels (35ppt) Light: Zooxanthellae need light to survive Sedimentation: Being covered with silt interferes with photosynthesis Desiccation: being exposed to air. The corals will die if exposed too long Coral likes areas with lots of waves: They are strong enough to withstand the pressure Freshwater means more food Waves remove silt New water brings more oxygen

13. Asexual Reproduction To reproduce coral can reproduce asexually or sexually Asexual reproduction in corals is called budding A baby polyp will begin growing off the adult When it is ready it will detach and live on its own This can not start new colonies, only help the old colony grow bigger This is a hydra (cousin to coral) with two buds. One bud (on the right) is older than the other.

14. Coral Reproduction Sexual reproduction is called spawning External fertilization It can start new colonies Sperm and eggs are released into the water column The fertilized egg is then called a planula The planula swims until it finds a good place to live

15. A New Home Corals now have a choice of where to live Corals are very sensitive and are rapidly dying People are trying to help by creating artificial reefs

16. Arguments for Artificial Reefs It can help build or rebuild a reef It will increase fish populations by making new habitats

17. Arguments Against Artificial Reefs Moveable Chemical leaking and leaching into the ocean It does not increase fish populations but rather moves them to one location away from their natural habitat which makes them easier to catch