Hardwood Hammocks These dense stands of hardwood trees, such as mahogany, gumbo-limbo, live oak and red maple, grow on slightly elevated islands located throughout the slough. Their branches form low canopies. Densely-packed shrubs and plants, including ferns and air plants, often grow in the shade and moisture beneath them. Many animal inhabitants also call the hammocks home. Among these are the white-tailed deer, green tree frogs and the highly endangered red-cockaded woodpecker. Hammocks rarely flood because of their elevation and they are protected from the region's seasonal fires by the natural moats which are created in the surrounding limestone by decaying plant material. These unique tree islands formed around 110 million years ago when seawater receded leaving corals and other ocean life exposed. As the corals died, they fossilized and formed limestone on which plants and animals formed thriving communities. Once ubiquitous throughout Florida and the West Indies, most of the hammocks have been destroyed. In the US, those that remain are concentrated in peninsular South Florida and the Keys.

Pinelands The pinelands are close geological cousins of the hardwood hammocks as they were created by the same process of seawater recession and the subsequent calcification of corals. Pinelands grow in elevated areas with outcroppings of rough limestone and thin soil. In these dry and rugged areas, slash pine is the dominant tree. Slash pines take any opportunity to root in the tiny cracks and crevices of the underlying limestone ridges. The slash pines are well adapted to periodic fires, which play an essential role in maintaining the health and survival of the pine community. Pine saplings require much sunlight in their initial growth stages and the fires help ensure that they are able to get it by limiting the population of hardwoods and other plants that would otherwise block out the needed light. At least 200 varieties of tropical plants grow in the pinelands making them the most diverse habitat in the Everglades. Possums, cotton mice, red-shouldered hawks and pygmy rattlers are among the most common residents. Many endangered species also call the Pinelands home. These include the red-cockaded woodpecker, the eastern indigo snake, the mangrove fox squirrel and the elusive Florida panther.

Freshwater Marl Prairie Marl is sediment that settles on limestone and allows seepage of water but not drainage. These shallow prairies look similar to the deeper freshwater sloughs which they border, but the sawgrass is not as tall or as dense and there are additionally occurrences of aquatic plants and low flowering shrubs like the dahoon holly and lantana. Marl prairie is flooded for 3-7 months of the year and is an important feeding ground for wading birds, especially during the dry season. When the water levels drop, fish and other food sources are easier to obtain. Winged inhabitants of this region include the endangered snail kite, the endangered wood stork, egrets and ibises, among others. One of the Everglades' most famous residents - the alligator - also calls the marl prairies home. The alligators use their feet and snouts to dig holes in the mud which form small, shallow ponds in the dry season. Small fish live in these "gator holes" until the rains come again. Wading birds feed and bathe here as well. Alligators also help other prairie residents by creating paths through the vegetation.

Cypress The cypress tree is a native deciduous conifer that can live in standing water. Cypress trees often grow tightly together in water-filled depressions to form "cypress domes," with trees at the center growing taller than those on the outside. Low-growing plants, such as the wax myrtle and buttonbush, thrive under the dome's protection. Drier land with poor soil is home to the dwarf cypress. Cypress trees growing in water-filled regions have a specialized root system. To obtain oxygen, the roots grow "breathing knees" that protrude above the water's surface. Growing on the trees themselves are many different types of epiphytes such as bromeliads, orchids, Spanish moss and ferns. These "air plants" live on other plants but are not parasitic and are able to survive by collecting water between their leaves which in turn becomes a home for insects, such as mosquitoes, small frogs and lizards. Cypress domes are extremely valuable to nesting birds. Avian residents in this habitat include the red-shouldered hawk, the great crested fly-catcher and several endangered species such as the wood stork.

Freshwater Slough Sloughs are the deeper, faster-flowing center portions of broad, marshy rivers. Moving at about 100 feet per day, sloughs carry freshwater south and west through the Everglades. The water flows around scattered tree-islands, or hammocks. The sawgrass in these areas has long, sharp and pointy leaves. It grows to six feet or more. The sloughs are important in that their slow rate of flow allows for significantly more evaporation than would occur in faster-moving waters. Their shallow depth and abundant plant life assists in the natural process of cleaning the water. An abundance of wildlife calls this region home, including alligators, wading birds and invertebrates. One species, the Florida apple snail, eats sawgrass and is in turn eaten by many birds including the limpkin and the snail kite.

Mangroves Mangrove swamps are found over the vast majority of Florida's southern and southwestern coastlines. They are found in tidal areas of brackish water, where saltwater mixes with freshwater. Three of the world's ten types of mangroves grow in south Florida. These are the red, white and black varieties. While the mangrove swamps are host to some of the region's most diverse animal life, the high salinity of the water makes it uninhabitable for almost all other plant life. One of the few exceptions is the abundant mangrove fern. The mangrove swamps provide feeding and nesting places for birds and act as a nursery for shrimp and fish. Among the many residents are crabs, mussels, star barnacles and sponges. Birds that live in the mangrove forests include herons, egrets, brown pelicans and frigate birds. Mammals, too, are well-represented. Bears roam here, as do swamp rats. While much of the Everglades region has an abundant alligator population, the mangroves are one of the few areas that also host the American crocodile.

Coastal Prairie Coastal prairies are irregularly flooded areas where the evaporation of sea water creates a very salty environment. They form when hurricanes and other storms move soil inland from the mudflats around Florida Bay and are susceptible to both flooding and fires which are often caused by strong storms. Often, these prairies will form in areas once dominated by mangroves that have been destroyed by natural disasters. The coastal prairie is full of hardy desert-like plants growing low to the ground. Succulents such as the saltwort and the glasswort are the sole source of food for the caterpillars of the eastern pygmy blue, the smallest butterfly found in Florida. Several types of turtles live here as well. The coastal prairies are one of the many areas in the Everglades which are under threat from invasive plant species.

Marine/Estuarine Florida Bay, one of the largest bodies of water in the Everglades, contains hundreds of square miles of marine bottom, much of which was covered by seagrass before a massive die-off began in 1987. Seagrass shelters fish and shellfish that serve as a food source for the larger animals in the bay. The Florida Bay is home to some of the region's most imperiled residents. Sea turtles and manatees swim here. In hard-bottomed areas are found hard and soft varieties of corals as well as sponges. There are abundant stingray and fish populations, such as sea trout, barracudas and sharks.