Coral Reef for Website

Coral Reefs

Organisms that build the Reef: Reef corals:

• CaCo3 (limestone)

• Cnidarians

• hard VS. soft coral (not reef builders)

Life cycle = planula larva ---- metamorphosis ---- adult polyp

Nutrition (get/ capture food): five methods

1.Photosynthetic zooxanthellae - dinoflagellates (need light)

• Gives coral color

• Hermatypic = coral with zooxanthellae

2. Prey on zooplankton with tentacles.

3. Catch zooplankton with sheets of mucus.

4. Mesenterial filaments- coiled filaments (secret digestive enzymes) are pushed out through mouth or body and absorb the food outside body from sediments.

5. Absorb dissolved organic matter DOM, directly from water (unique for animals).

Coral Reproduction:1. Budding off pieces (asexual) - colony

Coral Colony

2. Sexual

* Some hermaphrodites

*Some separate sexes

broadcast spawners

* Prodigal reproductive strategy

Other Reef Builders:• Oysters

• Polychete worms

• Shells of snails, clams, other mollusks, sea urchins, crustaceans, sponge.

• Coralline algae

• Produce “skeleton” of CaCO3.

• Form “algal ridge”- block waves and prevents erosion.

• Cements sediments in place “glue”.

Conditions for Growth:

• Clear water ---- light (zooxanthella and Coralline algae)

• Shallow water

• Warm water

•If stressed = bleaching - coral expels zooxanthellae

• Sediments - fine sediments are harmful because it smothers coral and blocks light.

•Expelling mucus carries sediment away.

• Salinity - coral sensitive to it.

• Pollution - more sediment/ introduced freshwater, pesticides, industrial wastes (farmland runoff), high concentration of nutrients (sewage) --- eutrophication - causes agal bloom.

Kind of Reefs:1. Fringing Reefs:

• Simplest kind

• Grow in narrow band/ fringe along shore

• Most vulnerable to pollution runoff

2. Barrier Reef:

• Farther from shore (up to 60 miles)

• Separated from shore by lagoon