An introduction to coral reefs across the world. Focus on reef building coral of the Tropics. Mentions Artificial Reefs and the ethics of created reefs.

1. Learning Objective:
By the end of the lesson I will be able to
describe what coral is, where it can be found
and explain how coral reefs are built.

2. What is coral?
 It’s a living organism!
 It is an invertebrate
 2 different types:
 Reef Building: Hermatypic
 Solitary: Ahermatypic
 Coral are 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

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

12. https://youtu.be/8RFeh1kWSdU

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

14. 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

15. 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.

16. 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

17. 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

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

19. 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

20. Reefs in North Carolina
 North Carolina has reefs too!
 They similar to tropical reefs
 Reef fish swept up on the Gulf
Stream live here until winter
 River beds that were covered
when sea levels rose
 Also made up of
 Low rock ridges
 Outcroppings
 Coral patches
 Ship wrecks