Corals

Corals

Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically live in compact colonies of many identical individual polyps. Corals are significant contributors to the physical structure of coral reefs that develop in tropical and subtropical waters.

Biology

Corals are composed of polyps, which are small, soft-bodied organisms. Each polyp has a stomach that opens at one end, surrounded by a ring of tentacles. The polyps secrete calcium carbonate to form a hard skeleton that protects their soft bodies. Over time, these skeletons build up to form coral reefs.

Symbiosis

Most corals have a mutualistic relationship with zooxanthellae, a type of photosynthetic algae. These algae live within the coral's tissues and provide the coral with nutrients produced through photosynthesis. In return, the coral provides the algae with a protected environment and the compounds necessary for photosynthesis.

Types of Corals

Corals can be broadly classified into two types:

• Hard Corals (Scleractinia): These corals build reefs by secreting calcium carbonate. They are the primary architects of coral reefs.
• Soft Corals (Alcyonacea): These corals do not produce a rigid calcium carbonate skeleton. Instead, they have a flexible, leathery structure.

Coral Reefs

Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals. They are often referred to as the "rainforests of the sea" due to their rich biodiversity.

Importance

Coral reefs provide habitat and shelter for many marine organisms. They also protect coastlines from the damaging effects of wave action and tropical storms, support fishing and tourism industries, and are a source of new medicines.

Threats to Corals

Corals face numerous threats, including:

• Climate Change: Rising sea temperatures can cause coral bleaching, where corals expel their symbiotic algae, leading to a loss of color and vital nutrients.
• Ocean Acidification: Increased CO2 levels lower the pH of seawater, reducing the availability of calcium carbonate needed for coral skeletons.
• Pollution: Runoff from land, including agricultural and industrial pollutants, can harm coral reefs.
• Overfishing: Disrupts the balance of reef ecosystems, leading to coral decline.

Conservation Efforts

Efforts to conserve coral reefs include:

• Establishing marine protected areas to limit human activities that damage reefs.
• Promoting sustainable fishing practices.
• Reducing carbon emissions to mitigate climate change.
• Restoring damaged reefs through coral gardening and transplantation.

See Also

• Great Barrier Reef
• Marine biology
• Biodiversity

References

• Veron, J. E. N. (2000). Corals of the World. Australian Institute of Marine Science.
• Hoegh-Guldberg, O. (1999). "Climate change, coral bleaching and the future of the world's coral reefs". Marine and Freshwater Research.

External Links

• Coral Reef Alliance
• National Oceanic and Atmospheric Administration