Pedia News

Corals


Corals
Corals are also important ocean resources. Corals are primarily important because they are the basis of an entire ecosystem and secondarily because they are a resource to us.

Vibrant, multicolored coral reefs surpass even tropical rainforests in their levels of biodiversity, supporting living corals, worms, conchs, spiny lobsters, and other invertebrates, as well as many species of fish.
Healthy coral reefs support tourism by recreational divers as well as commercial fishing. Almost half of all fishes depend on coral reefs and similar habitats for some of their lifestyles.
Corals are simple, radially symmetrical animals in the phylum Cnidaria. Cnidarian cells include the famous nematocysts, or stinging cells notable in sea jellies such as sea nettles, Portuguese man-of-war, and moon jellies. Corals and anemones are in the class Anthozoa, which appears in the fossil record more than 500 million years ago.
Corals

Corals

The reef-building corals are symbiotic associations between cnidarian animals and colorful photosynthetic creatures called zooxanthellae that live inside these animals. Corals precipitate calcium carbonate from seawater, which helps anchor them and build their skeletons, which we call the reef.
Reef-building corals require warmth, sunlight, and undiluted seawater. They are found in some of the sunniest, most beautiful tropical spots in the world.
Healthy ocean reefs are important for our survival on Earth because they are a keystone ecosystem. Reefs provide homes to many organisms that our planet needs to stay healthy. If reefs are destroyed, our health will be threatened by the uncertain effect on our ocean’s ability to support green algae, which produces 50% of the oxygen on our planet.
Despite their incredible value for ecological services and for humanity, the beneficial symbiosis between corals and zooxanthellae is under threat. Over the last century, pollution and climate change have taken their toll on reef ecosystems, particularly in the form of coral bleaching.
Bleaching occurs when the zooxanthellae are stressed by the temperature or chemical conditions in the surrounding water, which can break the important symbiotic bond and the algae are expelled. The corals can survive for a few months without their important symbionts, but if they do not get them back within about 10 weeks, the coral can die.
Experts estimate that almost 60% of the world’s coral reefs are in danger of bleaching, and the number of bleaching events recorded by marine biologists in the past century has increased by more than 10-fold.
Although coral reefs occupy only about 1% of the footprint of the world’s oceans, more than 25% of all marine life lives in these habitats. Without coral, there may be no fish. Without fish, what happens to humans?