What are Coral Reefs

Coral reefs are one of the most biologically diverse marine ecosystems on the Earth. Coral reefs play an important role in marine ecosystems and support the habitats of flora and fauna in the sea. The vast diversity of animal and plant species that contributes to its system are increasingly at risk due to climate change. India with its coastline extending over 7,500 km and subtropical climatic conditions has very few coral reef areas.

What are the salient features of Corals?

Coral polyps are one of the most productive ecosystems due to their complex structure, own primary production, hard base which acts as a substrate. So, they are one of the high bio-diversity areas on Earth.
In a coral reef ecosystem, invertebrates, vertebratesplants, and other life live in close association with the corals with very efficient resource recycling and coupling making it a highly productive and diverse ecosystem.
Corals polyps are called the tropical rainforests of the oceans due to their high biodiversity and productivity.
They occur in shallow tropical waters where seawater is clear, clean, and warm.
In the symbiotic relationship they live in, corals are generally slow-growing colonies of animals while the zooxanthellae algae are fast–growing.
The enormous nutrient recycling capacity of corals helps them grow in nutrient-poor waters.
There are cold-water corals also which inhabit deep, cold water. According to the united nations Environment Programme, there are more cold-water corals polyps worldwide than tropical polyps . The largest cold-water reef is the Rost reef off Norway.

Corals and Zooxanthellae

Many invertebrates, vertebrates, and plants live in close association with corals, with tight resource coupling and recycling, allowing coral reefs to have extremely high productivity and biodiversity, such that they are referred to as ‘the Tropical Rainforests of the Oceans’.
Scleractinian corals build skeletons of calcium carbonate sequestered from the water.
Scleractinian corals come under Phylum Cnidaria, and they receive their nutrient and energy resources in two ways.

They use the traditional cnidarian strategy of capturing tiny planktonic organisms with their tentacles (All about Phylum Cnidaria is given in NCERT).
Having a symbiotic relationship with a single cell algae known as ZOOXANTHELLAE.

Zooxanthellae are autorophic [prepare their own food] microalgaes belonging to various taxa in the Phylum Dinoflagellata.

Coral == Phylum Cnidaria.

Zooxanthellae == Phylum Dinoflagellata.

FAQs related with coral reefs

Ques 1. What is the importance of coral reefs?

Ans. Coral reefs provide numerous ecological and economic benefits. They support a wide range of marine life, including fish, invertebrates, and plants. Coral polyps also act as natural barriers, protecting coastlines from erosion and storm damage. Additionally, they contribute to tourism, fisheries, and the discovery of new medicines through their unique biodiversity.

Ques 2. How are coral polyps formed?

Ans. Coral reefs are formed over long periods of time by the growth and accumulation of coral polyps. Coral polyps are small, soft-bodied organisms that extract calcium carbonate from the ocean to build protective exoskeletons. When coral polyps die, their exoskeletons remain and new generations of coral grow on top, gradually forming the reef structure.

Ques 3. What are the main threats to coral reefs?

Ans. Coral reefs face threats from climate change, pollution, overfishing, and destructive practices. Rising temperatures cause coral bleaching, pollution harms water quality, and overfishing disrupts the delicate balance. Protecting reefs requires sustainable practices and addressing these challenges.