Coral island
Also called: Coral reef island · Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Class 11, Ch 2 "Structure and Physiography"; Class 11, Ch 6 "Natural Hazards and Disasters: Causes, Consequences and Management"
Meaning
A coral island is an island made of limestone from a coral reef. Coral reefs are built by colonies of tiny animals called polyps, which live together with algae. Polyps grow only in warm (about 20–29°C), clear, shallow, sunlit and salty seas, mostly between 30°N and 30°S. Over time, their limestone skeletons pile up into reefs, and the reefs can build up into low islands.
Example
All the islands of Lakshadweep, in the Arabian Sea off Kerala, are coral islands. The Maldives, to the south, are a chain of atolls (ring-shaped coral reefs around a lagoon).
Don't confuse with
- Andaman and Nicobar Islands: these are NOT coral islands. They only have fringing reefs (reefs attached to the coast) around them.