Coral Classification and Characteristics

Taxonomic Hierarchy of Corals

• Class Anthozoa
• Subclass Octocorallia
• Order Alcoynacea: Tubipora musica (Red organ-pipe coral)
• Order Gorgonacea: Corallium rubrum (Mediterranean red coral)

Coral Characteristics

• Corals have carotenoid pigments deposited in their skeleton
• They have a symbiotic relationship with zooxanthellae, which provide them with nutrients

Coral Fluorescence

• Living corals appear differently under normal light, electronic flash, and ultra-violet light
• Coral fluorescence is a result of this symbiotic relationship with zooxanthellae

Coral Reefs: Distribution and Environmental Limitations

• Coral reefs are found between latitudes 30o North and 30o South of the Equator
• They are limited to water depths of less than 50 meters and salinity between 30-36 ppt
• They require water temperatures above 18oC and good sunlight
• They also require a pre-existing hard substrate, clear waters, and circulation
• Pollution-free waters are essential for their survival

Coral Reefs in Southeast Asia

• They cover 34% of the world's total reef area (91,700 km2)
• The Great Barrier Reef (GBR) covers 62,800 km2
• The Southwest Pacific Islands have 27,060 km2 of coral reefs
• There are 600 hard coral species and 1,300 reef-associated fish species in Southeast Asia

Peninsular Malaysia

• Marine area: 614,000 km2
• Coastline: 7,275 km
• Reef area: 4,000 km2 (4% of total in SEA, 1.27% of total in the world)
• More than 75% of reefs are in East Malaysia, Sabah

Why Reefs Matter?

• Diversity: Coral reefs are often called the "Rainforests of the Sea"
• They provide food for one billion people in Asia alone
• They are a vital protein source for many humans

Coral Reefs

• They are the biggest and most spectacular structures made by living organisms
• They are composed of worms, shells, corals, algae, and many other organisms
• They are unparalleled in beauty, grandeur, high productivity, complexity, and mystery

The 'Coral Reef Paradox'

• Coral reefs are biologically rich areas that occur in nutrient-poor waters
• They are like oases in a watery desert

What are Corals?

• They are jellyfish-like organisms in the Order Scleractinia (true stony corals)
• They produce hard limestone (CaCO3) skeletons
• They have a symbiotic relationship with zooxanthellae
• They use tentacles with stinging cells to catch food

Zooxanthellae

• They are dinoflagellate, single-celled algae living within cells of polyps
• They are 8-12 µm in diameter and occur in large numbers (1-5 x 106 cells per cm2)
• They provide 94-98% of organic carbon products to the coral
• They may be expelled as a result of environmental stress or disease

Other Reef Builders

• Red coralline algae
• Calcareous green algae
• Millepora sp. (Fire-coral)
• Shell (e.g., giant clam)

Coral Eden

• Corals continuously contribute to alter the architecture of the planet
• They are chief architects of reefs
• A colony consists of thousands of polyps
• Symbiotic relationship with zooxanthellae gives the coral its color
• The largest structure built by living organisms other than man is visible from space

Growth Form of Hermatypic Corals

• Branching
• Foliose
• Massive
• Laminar / tabulate
• Columnar
• Encrusting
• Free-living

Heliopora coerulea (Blue Coral)

• It has a non-white skeleton due to the extraction of iron from the surrounding water
• It is listed as Vulnerable on the IUCN Red List of Threatened Species