February 11 – Reefer Gladness

Today’s Factismal: The Great Barrier Reef is larger (and much wetter) than the state of Tennessee.

Coral reefs are amazing structures. They are built up, layer by layer, by billions of tiny colonial organisms that look like jellyfish with a backbone. The resemblance is more than casual; corals are actually near relatives of the jellyfish and spend some time as free-floating critters before they settle down to a hard life of making hard rock. And, like their jellyfish cousins, corals consist of groups of genetically identical critters known as polyps, all living in cooperation.

A coral reef has many different types of coral (My camera)

A coral reef has many different types of coral (My camera)

And cooperation is the key to life as a coral. Not only to the polyps work together to form a limestone skeleton and to capture large prey, they also work with tiny algae called zooxanthellae that live inside each polyp. The zooxanthellae are a type of plankton that has evolved to live within corals and other sea creatures. In these safe harbors, zooxanthellae spend less time fleeing from predators and more time photosynthesizing food, some of which gets passed on to the coral.

Most of these corals play host to zooanthellae  (My camera)

Most of these corals play host to zooanthellae (My camera)

Because corals get so much energy from the zooxanthellae, they can only live in fairly shallow water. As a result, they are found mostly on the edges of continents and near islands and seamounts in the deep ocean. The great barrier Reef itself was formed when the glaciers melted after the last ice age 20,000 years ago, drowning the hills on Australia’s coast. The warm water, abundant nutrients, and high hills combined to create the perfect place to grow coral.

Coral reefs shelter 25% of all fish found in the ocean (My camera)

Coral reefs shelter 25% of all fish found in the ocean (My camera)

And grow it did. Today, the Great Barrier Reef is 1,600 miles long, or farther than it is from New York City to Key West. And it includes nearly 3,000 individual reefs clustered around 900 islands that provide homes to 30 types of whale, 200 types of bird, and 1,500 types of fish. But not all is well on the reef. As with any reef, there have been shipwrecks (more than 1,500) and overfishing and other problems. There are several research and conservation programs focused on the Great Barrier Reef, working to preserve it for future generations.

If you’d like to contribute to reef research, then think about joining REEF.org:
http://www.reef.org/

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