Yet, coral reefs are built by tiny animals, each smaller than a pencil eraser. Coral reefs are spectacular to behold, lush gardens in the sea, supporting a staggering diversity of marine life in a densely packed, thriving marine metropolis. In fact, coral reefs harbor the greatest diversity of life in the oceans, and are second only to tropical rainforests in the number of species found in one area on Earth. Nearly 400 million years ago, before there were any animals on land, the primitive ancestors of coral reefs formed in the seas. Today's coral reefs were built up during the last 10,000 years, as the last Ice Age ended and the glaciers receded.
Coral reefs are the oldest complex natural communities or ecosystems existing on Earth.
A dive on a coral reef is a voyage to another world. Life in a thousand forms. The coral reef is a gathering place in the ocean. It's a place which provides a variety of food and shelter in the tropical ocean, where such variety is hard to find. The entire tropical ocean depends upon the coral reef for sustenance.