Question

Why are coral reefs not found in the regions from West Bengal to Andhra Pradesh but are found in Tamil Nadu and on the east coast of India?

Answer 1

Conditions required for coral growth:

Corals colonise in the areas with the following:
$\bullet$ Optimal temperature
$\bullet$ High salt concentration
$\bullet$ Lack of sediments or silt in water (low siltation)
$\bullet$ Low inflow of fresh water from rivers

Coral distribution:

In West Bengal and Andhra Pradesh, freshwater is released from the Ganges and some other freshwater sources.

Hence, these requirements for the colonisation of corals are met in the regions of Tamil Nadu and on the east coast of India and not from West Bengal to Andhra Pradesh.