Corals get their vibrant colors from the algae they host.
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. Coral polyps are actually translucent animals. Reefs get their wild hues from the billions of colorful zooxanthellae (ZOH-oh-ZAN-thell-ee) algae they host. When stressed by such things as temperature change or pollution, corals will evict their boarders, causing coral bleaching that can kill the colony if the stress is not mitigated. 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. Coral reefs teem with life, covering less than one percent of the ocean floor, but supporting about 25 percent of all marine creatures. However, threats to their existence abound, and scientists estimate that human factors—such as pollution, global warming, and sedimentation—could kill 30 percent of the existing reefs in the next 30 years. Fast Facts:
Type: Invertebrate
Diet: Carnivore Average life span 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 Protection status: Endangered 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. Size relative to a tea cup: What is Coral?
Despite the fact that corals look more like rocks or plants, they are definitely animals. Coral colonies are composed of many tiny, cup-shaped animals called polyps, which are related to jellyfish. A single coral polyp may be as large as a saucer or smaller than the head of a pin. Millions of polyps working together in a cooperative colony generation after generation create the limestone skeletons that form the framework of the beautiful coral reef... How Do Coral Reefs Form?
Stony corals are a remarkable group of animals that inhabit tropical marine waters around the world and form vast colonies known as coral reefs...
Facts About CoralIf you've ever visited an aquarium or gone snorkeling when on holiday, you're probably familiar with a wide variety of corals. You may even know that corals play a fundamental role in defining the structure of marine reefs, the most complex and diverse ecosystems in our planet's oceans. But what many don't realize is that these creatures, which resemble a cross between colorful rocks and various bits of seaweed, are in fact an animals. And amazing animals at that...
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Organ Pipe Coral The rocky structure that make up coral reefs are actually a build-up of calcium secreted by coral polyps.
Pillar Coral Coral polyps can reproduce asexually, forming cloned buds that separate from the "parent." They can also release sperm and eggs into the ocean. Fertilized eggs develop into larva, which float off to start a new colony.
Pipe Coral Corals get their vibrant colors from the algae they host.Cavernous Star Coral Coral and sea anemones are in the same family of stinging invertebrates. This close-up of a cavernous star coral shows the individual polyps, which resemble tiny sea anemones.
Cavernous Star Coral Coral and sea anemones are in the same family of stinging invertebrates. This close-up of a cavernous star coral shows the individual polyps, which resemble tiny sea anemones.
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