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View this presentation for background information on coral reef ecosystems.
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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
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
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
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
Coral are Cnidarians
Soft bodied Carnivorous Stinging tentacles
arranged in a circle around their mouth
Body symmetry Specialized tissues
Cnidarians
Usually two life stages: Polyp Medusa
Gastrovascular cavity Food is broken down
here but digested intracellularly
Cnidarians
Respiration and waste removal takes place through body walls
Nerve net Some have a
hydrostatic skeleton Some move through
jet propulsion
Anatomy of Coral
The coral polyps build a calcium carbonate cup called a corallite to live in
Coral has stinging cells called nematocysts
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
Coral and Zooxanthella Symbiotic relationship Zooxanthella is an algae that lives in the
skin of coral Coral provides protection Zooxanthella provides food and color!
Coral is Picky
Very specific habitats: Temperature: 73-75F 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
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.
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
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
Arguments for Artificial Reefs
It can help build or rebuild a reef
It will increase fish populations by making new habitats
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
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