OUTLINE

I.                     Description

a.        Invertebrates with mutualistic relationships

b.        Members of Cnidarian Phylum

c.        Benthic and colonial animal

d.        Physical appearance and characteristics

II.                   Classification

a.        Environment

b.        Anatomy

c.        Anthozoa

                                       i.      Subclass Alcyonaria (= Octocorallia) (eight tentacles)

                                       ii.      Subclass Zoantharia (= Hexacorallia) (more than 8 tentacles - typically 12)

III.                 Behavior

a.        Feeding Behavior

b.        Reproduction

IV.                 Significance

a.        Primary producers

b.        Produce compounds with potential medical importance

c.        Tourism

V.                   Diseases Affecting Corals

a.        White band disease (WBD)

b.        Black band disease (BBD)

c.        Bacterial infection

d.        Shut down reaction

e.        Tumors

f.         Parasitic worms

 

ABSTRACT

 

Corals (class Anthozoa), which include sea anemones (order Actiniaria), are gastrovascular marine cnidarians (phylum Cnidaria) existing as small sea anemone-like polyps, typically forming colonies of many individuals. The group includes the important reef builders known as hermatypic corals, found in tropical oceans. There are several other types of corals, notably the octocorals (subclass Octocorallia) and corals classified in other orders of subclass Zoantharia: to wit, the black corals (order Antipatharia) and the soft corals (order Zoanthinaria).

                What we see as a coral is a head of many individual, yet genetically identical, polyps. The polyps are multicellular organisms that feed on a variety of small organisms, from microscopic zooplankton to small fish. Aside from feeding on plankton, corals belong in a symbiotic relationship with a class of algae, zooxanthellae. Typically a polyp will harbour particular species of algae, which will photosynthesize and thereby provide energy for the coral and aid in calcification, while living in a safe environment and using the carbon dioxide and nitrogenous waste produced by the polyp.

Coral can be sensitive to environmental changes, and as a result are generally protected through environmental laws. A coral reef can easily be swamped in algae if there are too many nutrients in the water. Coral will also die if the water temperature changes by more than a degree or two beyond its normal range or if the salinity of the water drops. In an early symptom of environmental stress, corals expel their zooxanthellae; without their symbiotic unicellular algae, coral tissues are colorless, revealing the white of their calcium carbonate skeletons, an event known as “coral bleaching”. These stresses can also lead to the other previously mentioned diseases.