Introduction
Corals are marine invertebrates belonging to the phylum Cnidaria and class Anthozoa. They typically live in compact colonies of many identical polyps. Coral reefs are large underwater structures made of calcium carbonate secreted by corals. These reefs are among the most diverse and productive ecosystems on Earth, often called the 'rainforests of the sea'.
 |
| Coral Reef |
The formation of coral reefs is a gradual process involving the growth of coral polyps, which secrete calcium carbonate exoskeletons. Over time, these structures accumulate, forming massive reef systems.
Key steps include:
1. Settlement of coral larvae on a hard substrate.
2. Growth of coral polyps and secretion of calcium carbonate.
3. Symbiotic relationship with zooxanthellae (algae) that provide energy via photosynthesis.
4. Accumulation of skeletal material forming large reef complexes.
Types of Coral Reefs
1. Fringing Reefs
Fringing reefs are directly attached to the shore of an island or continent. They are the most common type of reef. Example: Reefs along the coast of the Red Sea.
2. Barrier Reefs
Barrier reefs are separated from the mainland or island shore by a deep lagoon. They run parallel to the coastline. Example: The Great Barrier Reef in Australia.
3. Atolls
Atolls are ring-shaped reefs that encircle a lagoon, often formed on sinking volcanic islands. Example: Bikini Atoll in the Marshall Islands.
4. Patch Reefs
Patch reefs are small, isolated reefs that grow on the continental shelf or inside atolls and lagoons. Example: Patch reefs in the Florida Keys.
5. Ribbon Reefs
Ribbon reefs are long, narrow, winding reefs that develop on the continental shelf, often parallel to the shore. Example: Ribbon Reefs in the northern part of the Great Barrier Reef.
Adaptive Significance of Coral Reefs
1. Provide habitat and shelter for thousands of marine species.
2. Act as natural barriers protecting coastlines from erosion and storms.
3. Support fisheries and provide food resources.
4. Serve as sources of new biochemical compounds useful in medicine.
5. Help maintain biodiversity and ecological balance in marine environments.
Frequently Asked Questions (FAQs)
Q1. What is the primary component of coral reefs?
A1. Coral reefs are primarily composed of calcium carbonate (CaCO3).
Q2. Why are coral reefs called the 'rainforests of the sea'?
A2. Because they host extremely high biodiversity, similar to rainforests.
Q3. Can coral reefs survive without sunlight?
A3. Most reefs require sunlight as the symbiotic algae (zooxanthellae) need light for photosynthesis.
Q4. Which is the largest coral reef system in the world?
A4. The Great Barrier Reef in Australia.
Multiple Choice Questions (MCQs)
1. Which phylum do corals belong to?
(a) Porifera (b) Cnidaria (c) Mollusca (d) Annelida
Answer: (b) Cnidaria
2. The Great Barrier Reef is located in:
(a) Red Sea (b) Caribbean Sea (c) Pacific Ocean (d) Indian Ocean
Answer: (c) Pacific Ocean
3. Atolls are usually formed around:
(a) River deltas (b) Volcanic islands (c) Sandy beaches (d) Fjords
Answer: (b) Volcanic islands
4. Coral reefs are made up of:
(a) Silica (b) Calcium carbonate (c) Sodium chloride (d) Magnesium carbonate
Answer: (b) Calcium carbonate
5. Which type of reef lies directly attached to the shore?
(a) Atoll (b) Barrier reef (c) Fringing reef (d) Patch reef
Answer: (c) Fringing reef
Worksheet
1. Define coral reefs and explain how they are formed.
2. Differentiate between fringing reef, barrier reef, and atoll with examples.
3. Explain the ecological and economic importance of coral reefs.
4. Label a diagram of coral reef formation (activity).
5. Short Notes: (a) Zooxanthellae (b) Patch Reefs (c) Adaptive significance of coral reefs.
References
1) Barnes, R.D. (1987). Invertebrate Zoology. Saunders College Publishing.
2) Ruppert, E.E., Fox, R.S., & Barnes, R.D. (2004). Invertebrate Zoology: A Functional Evolutionary Approach. Brooks/Cole.
3) Nybakken, J.W. (1993). Marine Biology: An Ecological Approach. Harper Collins.
4) Veron, J.E.N. (2000). Corals of the World. Australian Institute of Marine Science.
0 Comments