SIGHTSEERS
Key Largo National Marine Sanctuary
by Randy Karr

Its not pirate plunder, but marine marvels, that entice travelers to visit Florida’s Key Largo National Marine Sanctuary.

Adjacent to the Florida Keys, which extend 220 miles southwest from the southern tip of the Florida peninsula, is a 3,200 square mile underwater preserve protecting marine environments that include seagrass, meadows and mangrove islands. This reef ecosystem, the third largest in the world, also includes the 200-square-mile John Pennekamp Coral Reef State Park, the first undersea park in the United States.

Coral reefs, like tropical rainforest, foster biological diversity. They are also fragile environments that provide food, shelter and breeding areas for marine plants and animals. Living among the corals are sponges, shrimp, crabs, turtles, lobsters, eels and nearly 600 species of fish. While coral reefs cover less than 1 percent of the Earth’s surface, they are home to 25 percent of all ocean fish species.

Corals are the exoskeleton tiny sea animals called polyps. Polyps start life as free-floating larvae that eventually settle on the sea floor, where they then secrete a limestone skeleton around their bodies. When the polyp dies, its skeleton remains, providing the foundation on which other polyps build their skeletons. It is this building process that makes up the framework of a coral reef, considered the largest living structure on the planet. Depending on the species of coral, a reef can grow at the rate of a half-inch to seven inches a year.

Not all corals form hard skeletons. Some are flexible. Octocorals, such as sea fans and sea plumes, sway in the ocean current feeding on plankton. Even though corals are classified as animals, there are extremely small algae that live in the animal’s tissue. This plant produces much of the color seen in reef corals.

There are 2,000 species of coral, each with a descriptive name. Brain coral look like a brain. Elkhorn coral looks like an elk horn. Other fanciful coral names include elephant nose, bird nest, cauliflower, pineapple, pipe organ, cat’s paw, candy cane, Christmas tree and hairy mushroom.

Out on the reef, it is a fish-eat-fish world. Spiny lobsters prey on crabs, conchs and clams and, in turn, are preyed upon by sharks, octopuses and groupers. To keep from being eaten, some creatures simply hide. Others are masters of camouflage. Most reef fish sport bright colors as a way of saying they taste bad or are poisonous. The puffer fish inflates itself like a balloon, thereby making itself too large to fit in a predator’s mouth.

Some marine creatures have a symbiotic relationship, where one helps the other to stay alive. The cleaner shrimp helps the moray survive by entering its mouth to remove parasites, dead tissues and bits of food. In return, the moray offers the shrimp a safe haven in its mouth from passing predators. Likewise, some species of small fish nibble away on big fish, even inside their mouth, to rid it of parasites, fungi and dead tissue. It’s a win-win. The little fish eats while the big fish gets tidied up.

Coral reefs, among the most beautiful and diverse of all living communities, are vulnerable to damage from human activities. If its present rate of destruction continues, 70 percent of the world's coral reefs will be destroyed by the year 2050.

For more about Key Largo National Marine Sanctuary, visit floridakeys.noaa.gov.

© 2010 Randy Karr