Five Strange Facts about Coral

In the new series Kingdom of the Oceans, viewers explore the world underwater and discover creatures and behaviors they may have never seen before. Nearly three quarters of our planet lies under water and there is a tremendous amount of life to discover and much of it is strange and surprising, such as the coral organisms that make up a coral reef. Did you think that a coral reef was just a rocky harbor for other creatures? Think again and check out these five strange facts about coral.

Coral Is Smaller than a Tea Cup

The animals that make up a coral reef are called polyps and they can actually 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. A single polyp is no bigger than a tea cup, but when you join them all together, you create a massive community that is used by a multitude of species. The largest coral reef, The Great Barrier Reef off the coast of Australia is more than 1,600 miles long and can be seen from outer space.

Coral Reefs Are Colorless

When you think of coral reefs, you imagine their vibrant colors, but 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. These algae use photosynthesis to survive and then this process adds nutrients to the environment which benefits the coral. The variety of colors in a color reef is due to a several factors. Environmental influences as well as the species that share the reef system create color variations. The color of a coral reef can also indicate whether or not the coral organisms are healthy or unhealthy.

Coral Reefs Are Carnivores

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 to catch prey. They are nocturnal so you usually can only catch them hunting at night. Using their tentacles, they scoop up zooplankton, which are tiny floating animals and even small fish. The stomach cavities corals in a reef system are interconnected. Food obtained by one polyp can be passed to other polyps in the colony.

Coral Reefs Are a Map to Climate Change

Corals are so sensitive to changes in the world climate that scientists study coral reef fossils to construct highly detailed chronologies of prehistoric climate patterns. When corals experience increased water temperatures, mass coral bleaching can occur.  When coral polyps, stressed by temperature or a variety of other environment factors, they expel the symbiotic algae that live within their tissues. When the algae are expelled, the coral appears white or “bleached.”

Coral Reefs Have Showy Sex Lives

Some species of coral reproduce by coral spawning. This means that in unison and in some cases on one particular night a year, the coral eject large quantities of eggs and sperm into the surrounding water. This always happens at night and just after the full moon. Trillions of eggs and sperm are released all at once. When this occurs, the eggs and sperm fertilize in the water and then if the larvae that grow survive, they settle back to the ocean floor, attach themselves to a hard surface and grow.

The coral reef is a world where even the rock is alive. There is so much more than coral, however. Amazing animals live, hide, and hunt on the coral reef. Tune in to Kingdom of the Oceans: Predator’s Paradise this Sunday at 8PM et/pt and discover the wonders of a coral reef


  1. Jessica Carilli
    March 20, 2013, 10:49 pm

    Here is my #scisplain blog post on nit-picky things wrong with your story about corals –

  2. Hafeez Baig
    peshawar Pakistan
    April 29, 2013, 10:47 am

    Great post

    Interesting strange facts

  3. 樱花
    United States
    September 6, 2013, 4:21 pm

    That is wrong! For one coral is very colorful. Two coral is BIG! Some are the size of teacups but most are very big.

  4. […] by their algae neighbors, but they’re not always so gracious. Coral polyps “have barbed, venomous tentacles they can stick out to catch prey. They are nocturnal so you usually can only catch them hunting at […]

  5. niggas
    February 27, 2015, 12:43 pm