Coral Reefs
Coral Reefs
Coral reefs are similar to rain
forests in that they are complex
and diverse
Coral Reefs
Coral reefs are made of calcium
carbonate CaCO3 deposited by
reef-building organisms like coral.
Coral Reefs
Coral polyp is a sac like stage of
a Cnidarian with mouth and
tentacles on top.
Coral polyp
Coral Reefs
What is a coral colony?
“Founder” coral divides over and
over so all are clones that have a
connected digestion system and
share a common nervous system.
Touch one and they all respond.
Coral Colony cutaway
Coral Colony
Coral Reef
What are zooxanthellae?
Dinoflagellates that live within animal tissue
Have symbiotic mutualistic relationships with
organisms providing food and color
• They do photosynthesis and pass on some of
the organic matter to the coral.
• Feed coral from inside.
• Enable coral to make CaCO3 faster
zooxanthellae living in a mutualistic relationship with coral
Five Ways Coral Feed
1.Zooxanthellae are most important source of
nutrition
2.Capture zooplankton with stinging
nematocysts on tentacles
3.Capture zooplankton with mucus nets
4.Digest organic material outside the body
with mesenterial filaments
5.Absorb DOM dissolved organic matter
Coral polyp
Stinging Nematocysts
mesenterial filaments
Encrusting Coralline Algae
• Deposit of CaCO3 (limestone) add to
structure of reef
• Forms algal ridge, block waves, prevents
erosion
• Cements sediments in place,keeps reef
from washing away
• Food source for fish
Encrusting Coralline Algae
Encrusting Coralline Algae
algal ridge
Coral reproduction
• Sometimes asexual, cloning
• Some corals hermaphroditic….. Some
separate sexes
• Have mass spawning ex. Great Barrier
Reef between Oct- Nov
• Larva is called planula larva
Budding
Budding
coral spawning
coral spawning
Life cycle of a coral polyp
coral spawning
coral spawning
Conditions for reef growth
•
•
•
•
Shallow clear water
Good light
Warm water- just right
Stable salinity
Clear Water
Other Reef Builders:
• Oysters
• Polychete worms
• Shells of snails, clams, other mollusks, sea urchins,
crustaceans, sponge.