• key
    The Florida Keys National Marine Sanctuary surrounds most of the Florida Keys.

    Photograph by Emory Kristof, National Geographic

    Keychain
    There are approximately 1,700 islands in the Florida Keys.

    Tobacco Caye
    Tobacco Caye is an artificial key off the coast of Belize. A local fisherman constructed the island by piling soil and sand on top of trash heaps. Tobacco Caye is now home to a mangrove forest, coconut palms, a fishing area that includes sharks and conchs, and about 20 residents.

    A key is a small, low-lying coral island. Like all coral islands, keys are the remnants of ancient coral reefs, and many keys are still ringed by healthy reef ecosystems.

    Over time, the top of a coral reef is exposed to the surface. Waves and wind slowly transport sediment, sand, shells, and even living organisms to the exposed reef's depositional node. A depositional node is simply a part of the reef where currents are less likely to erode the material deposited there. Usually, depositional nodes are at the reef's highest elevation.

    Keys can provide a rich, diverse ecosystem. The nutrient-rich sand and sediment often support coconut palms and other plants. Sturdy mangrove forests often thrive in the coastal areas of keys. The shallow, shadowed waters of these mangrove forests offer habitats for shorebirds, such as egrets and herons.

    Coral reefs that often surround keys provide one of the most biodiverse habitats on the planet. Coral reefs boast an array of fish, sponges, marine mammals, and crustaceans, in addition to the corals that support the ecosystem.

    Native animal species in keys are often smaller than their mainland counterparts. Key deer, for instance, are an endangered species native to the Florida Keys. Key deer are related to white-tailed deer, but adapted to their small, isolated environment by evolving to grow less than half the size of their North American cousins. Key deer weigh only 25-25 kilograms (55-75 pounds), while white-tailed deer weigh around 60 to 130 kilograms (130 to 290 pounds).

    The soil and sediment that support such diverse, healthy ecosystems can also support agriculture. People have been living on keys for thousands of years. In addition to coconuts, key residents often harvest mangoes, dates, guavas, and other tropical fruits. Most livestock on keys, usually pigs, are introduced species.

    Agriculture is not a strong economic activity on keys, however. Fishing and tourism are the keys of key economies. Tropical waters surrounding keys include grouper and sharks, and deeper waters include populations of sailfish, tuna, and other large species.

    Keys' white sand beaches and tropical waters make them popular vacation spots. The Florida Keys, Caribbean keys (often called cays) and the keys of Australia's Great Barrier Reef draw millions of tourists every year.

    The same elements that make keys so inviting can also make them vulnerable. Thousands of tourists and a growing service-based economy (including hotels, charter boats, and fishing opportunities) can stress the key environment. Overfishing, especially for sport fish such as sailfish, can dwindle local fisheries.

    Keys are also at risk from hurricanes, cyclones, and sea level rise. These forces can erode the low-lying islands. Even strong tides can have an impact on key beaches and coastal areas. Small keys in the Caribbean Sea have disappeared entirely—becoming sandbars—after a busy hurricane season.

  • Term Part of Speech Definition Encyclopedic Entry
    agriculture Noun

    the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

    Encyclopedic Entry: agriculture
    coral island Noun

    low-lying island whose land is made up of organic material associated with coral.

    coral reef Noun

    rocky ocean features made up of millions of coral skeletons.

    crustacean Noun

    type of animal (an arthropod) with a hard shell and segmented body that usually lives in the water.

    current Noun

    steady, predictable flow of fluid within a larger body of that fluid.

    Encyclopedic Entry: current
    cyclone Noun

    weather system that rotates around a center of low pressure and includes thunderstorms and rain. Usually, hurricanes refer to cyclones that form over the Atlantic Ocean.

    depositional node Noun

    place on a reef where currents and winds deposit sediment, sand, and other materials.

    ecosystem Noun

    community and interactions of living and nonliving things in an area.

    Encyclopedic Entry: ecosystem
    elevation Noun

    height above or below sea level.

    Encyclopedic Entry: elevation
    endangered species Noun

    organism threatened with extinction.

    Encyclopedic Entry: endangered species
    erode Verb

    to wear away.

    expose Verb

    to uncover.

    Florida Keys Noun

    chain of small islands off the southern coast of the U.S. state of Florida.

    habitat Noun

    environment where an organism lives throughout the year or for shorter periods of time.

    Encyclopedic Entry: habitat
    hurricane Noun

    tropical storm with wind speeds of at least 119 kilometers (74 miles) per hour. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region.

    introduced species Noun

    a species that does not naturally occur in an area. Also called alien, exotic, or non-native species.

    key Noun

    small, low island on a coral reef, also known as a cay.

    Encyclopedic Entry: key
    livestock noun, plural noun

    animals raised for sale and profit.

    mangrove Noun

    type of tree or shrub with long, thick roots that grows in salty water.

    marine mammal Noun

    an animal that lives most of its life in the ocean but breathes air and gives birth to live young, such as whales and seals.

    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    overfish Verb

    to harvest aquatic life to the point where species become rare in the area.

    remnant Noun

    something that is left over.

    sandbar Noun

    underwater or low-lying mound of sand formed by tides, waves, or currents.

    sea level rise Noun

    increase in the average reach of the ocean. The current sea level rise is 1.8 millimeters (.07 inch) per year.

    sediment Noun

    solid material transported and deposited by water, ice, and wind.

    Encyclopedic Entry: sediment
    service-based economy Noun

    a system of production, distribution, and consumption of goods and services based on the manufacture of finished goods and providing of services.

    soil Noun

    top layer of the Earth's surface where plants can grow.

    stress Verb

    to strain or put pressure on.

    tide Noun

    rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun.

    Encyclopedic Entry: tide
    tropical fruit Noun

    any fruit-bearing trees that do not tolerate frost.

    vulnerable Adjective

    capable of being hurt.

    wave Noun

    moving swell on the surface of water.

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