Average lifespan in the wild: Polyp, 2 years to hundreds of years; colony, 5 years to several centuries
Size: Polyp, 0.25 to 12 in (0.63 to 30.5 cm)
Group name: Colony
Did you know? Corals are so sensitive to climatic change that scientists study coral reef fossils to construct highly detailed chronologies of prehistoric climate patterns.
Protection status: Endangered
Coral organisms, called polyps, can live on their own, but are primarily associated with the spectacularly diverse limestone communities, or reefs, they construct.
Coral polyps are tiny, soft-bodied organisms related to sea anemones and jellyfish. At their base is a hard, protective limestone skeleton called a calicle, which forms the structure of coral reefs. Reefs begin when a polyp attaches itself to a rock on the sea floor, then divides, or buds, into thousands of clones. The polyp calicles connect to one another, creating a colony that acts as a single organism. As colonies grow over hundreds and thousands of years, they join with other colonies and become reefs. Some of the coral reefs on the planet today began growing over 50 million years ago.
Where do Corals live?
Corals live in tropical waters throughout the world, generally close to the surface where the sun's rays can reach the algae. While corals get most of their nutrients from the byproducts of the algae's photosynthesis, they also have barbed, venomous tentacles they can stick out, usually at night, to grab zooplankton and even small fish. Western Australia’s coral reefs are amazing and unique, because they grow much further south, in much colder waters, than reefs elsewhere in the world. At the Abrolhos Islands, offshore from Geraldton, there are well-developed and stunningly beautiful coral reefs where they should not (in theory) be growing. There is even a beautiful pink coral reef at Pocillopora Reef at Rottnest Island, offshore from Perth.
What is a Coral reef?
Coral reefs are like underwater cities built from living animals (coral polyps) which usually live together in colonies. Hard corals, which are the only types of corals to form coral reefs, produce limestone skeletons. Amazingly, they do this with the help of tiny microscopic plants that actually live inside them. These plants give the corals their colours and capture energy from the sun by photosynthesis - just like plants in your garden! The sugars and oils they produce are also used by the corals.
What does a coral reef look like?
Coral reefs may look quite different to one another, depending on the species they are made up of. They come in a fantastic range of shapes and colours. There are staghorn corals with delicate branching structures that look a little like the horns of stags, mushroom corals, bubble corals, cabbage corals, honeycomb corals, brain corals, plate corals, blue corals and many many more. Sometimes a reef may be formed mostly of one particular type and sometimes you can see lots of different species living together.
Why is a Coral reef important?
Coral reefs form important homes for hundreds of colourful fish, sea stars, crabs, marine worms with their colourful feeding tentacles, exquisite shellfish, and a myriad of other animals. If coral reefs die all the animals that depend on them would disappear too.
Did you know?
Corals get their vibrant colors from the algae they host.
Coral reefs grow less than three centimetres each year, so it takes many, many years for a large reef to form. Coral reefs have existed for more than 200 million years.
Download free Coral wallpapers, click on the image to open the large version.
Coral wallpaper 1
Coral wallpaper 2
Coral wallpaper 3
Coral wallpaper 4
Coral Coloring pages
Print free Coral coloring pages, click on the image to open the large version.