Corals reefs appear as isolated formations in the fossil record over four hundred
million years ago, corals are extremely old animals that have evolved into modern reef creating forms over the last twenty-five million years. Coral reefs are unique and the most gorgeous and diverse out of all marine habitats. Organisms that provide the matrix for he growing reef are the dominant ones known as frame builders. Topographical, the reef is very complex. Thousands of fish and invertebrates live in association with reefs, because of the complexity. For example, in Caribbean reefs, several hundreds species of colonial invertebrates can be found living on the undersides of platy coral. It is common for a reef to have several species of snails, sixty species of coral, and many species of fish. Out of all oceanic habitats, reefs seem to have the greatest development of complex symbiotic associations.
Coral reefs are very important to humans as well. The value of coral reefs estimate to thirty billion U.S. dollars, even as much as 172 U.S. dollars every year, used for food, the safety of shorelines, jobs for tourism, and even for medicines. Humans also pose as an incredible threat to coral reefs as well. Overfishing and destructive fishing, pollution, changing oceanic chemistry, and invasion of species are taking a large toll on the coral reefs, and n some places have destroyed them. In many places they are a faded shadow in comparison of what they used to be.
Most vertebrates living in coral reefs are fish. The Coral Triangle alone holds more than 2,000 fish species. Sharks are the top predator in coral reefs. For example, black-tip and white-tip reef sharks hunt in the Indo-Pacific coral reefs. Parrotfish inhabit coral reefs as well. Although the most abundant reef are wrasses which means they are a family of fish that travel together are brightly colored have spiny fins and thick lips.
Another vertebrate in coral reefs are sea turtles. Sea turtles are one of the world’s oldest creatures. Seven species that are found today have been around for 110 million years, since the age of the dinosaurs. Unlike regular turtles, sea turtles can’t retract their legs and had into their shells. Their shell colors varies between yellow, greenish and black, depending on species. The shell is streamlined for swimming through the water.
Sea-grasses are thriving plants, which have descended from land plants and...