Coral Reefs | Environment for UPSC 2025 (Pre & Mains) PDF Download

 Page 1


 
CORAL REEFS 
Page 2


 
CORAL REEFS 
WHAT WILL WE STUDY 
• FEATURES 
• CONDITIONS FOR THEIR FORMATION 
• TYPES OF CORAL REEFS 
• PRESENCE IN INDIA 
• CORAL BLEACHING 
• COLD CORALS 
 
Page 3


 
CORAL REEFS 
WHAT WILL WE STUDY 
• FEATURES 
• CONDITIONS FOR THEIR FORMATION 
• TYPES OF CORAL REEFS 
• PRESENCE IN INDIA 
• CORAL BLEACHING 
• COLD CORALS 
 
These are underwater structures made from calcium carbonate 
secreted by corals. 
Often called “rainforests of the sea” as they form some of the most 
diverse ecosystems on Earth. 
 
An individual coral is known as a polyp which 
have a symbiotic relationship with plant-like cells called 
zooxanthellae. 
The zooxanthellae living in the soft tissue of a coral polyp use 
sunlight to produce food through photosynthesis and create a 
byproduct that the coral can use as food.  
Thus, zooxanthellae provide corals with food; in return, the coral 
provides the zooxanthellae with shelter and nutrients. 
Corals also capture food.  
At night, they stretch out their stinging tentacles and catch the 
microscopic organisms that float in the water and digest them in 
their stomachs.  
So, corals have two ways of getting food —through zooxanthellae 
and capturing microscopic organisms. 
 
 
Page 4


 
CORAL REEFS 
WHAT WILL WE STUDY 
• FEATURES 
• CONDITIONS FOR THEIR FORMATION 
• TYPES OF CORAL REEFS 
• PRESENCE IN INDIA 
• CORAL BLEACHING 
• COLD CORALS 
 
These are underwater structures made from calcium carbonate 
secreted by corals. 
Often called “rainforests of the sea” as they form some of the most 
diverse ecosystems on Earth. 
 
An individual coral is known as a polyp which 
have a symbiotic relationship with plant-like cells called 
zooxanthellae. 
The zooxanthellae living in the soft tissue of a coral polyp use 
sunlight to produce food through photosynthesis and create a 
byproduct that the coral can use as food.  
Thus, zooxanthellae provide corals with food; in return, the coral 
provides the zooxanthellae with shelter and nutrients. 
Corals also capture food.  
At night, they stretch out their stinging tentacles and catch the 
microscopic organisms that float in the water and digest them in 
their stomachs.  
So, corals have two ways of getting food —through zooxanthellae 
and capturing microscopic organisms. 
 
 
Page 5


 
CORAL REEFS 
WHAT WILL WE STUDY 
• FEATURES 
• CONDITIONS FOR THEIR FORMATION 
• TYPES OF CORAL REEFS 
• PRESENCE IN INDIA 
• CORAL BLEACHING 
• COLD CORALS 
 
These are underwater structures made from calcium carbonate 
secreted by corals. 
Often called “rainforests of the sea” as they form some of the most 
diverse ecosystems on Earth. 
 
An individual coral is known as a polyp which 
have a symbiotic relationship with plant-like cells called 
zooxanthellae. 
The zooxanthellae living in the soft tissue of a coral polyp use 
sunlight to produce food through photosynthesis and create a 
byproduct that the coral can use as food.  
Thus, zooxanthellae provide corals with food; in return, the coral 
provides the zooxanthellae with shelter and nutrients. 
Corals also capture food.  
At night, they stretch out their stinging tentacles and catch the 
microscopic organisms that float in the water and digest them in 
their stomachs.  
So, corals have two ways of getting food —through zooxanthellae 
and capturing microscopic organisms. 
 
 
ZOOXANTHELLAE 
Zooxanthellae are single-celled dinoflagellates 
(unicellular algae) that are able to live in 
symbiosis with diverse marine invertebrates 
including corals, jellyfish, and nudibranchs.