National Marine Sanctuary Habitats

Although the Florida Keys area is world known for the reef system, other productive marine communities including seagrass meadows and mangrove forests occur within the waters of the Florida Keys. Seagrass meadows are the most abundant habitat within the Keys and when combined with those to the north in the Florida Bay, create the most extensive seagrass bed in the world. These communities form the marine ecosystem upon which the fishery and tourism industries of south Florida are dependent upon.

Coral Reefs

Coral reefs are among the most diverse communities on this planet, often described as "rainforests of the sea". Reefs occur in clear, shallow waters throughout tropical regions across the globe. Formed by the calcium carbonate skeletons, the backbone of the reef is built by tiny coral animals that make up large coral colonies. Coralline algae produce calcium carbonate, which cements the coral skeletons together, forming the continuous reef structure. The skeletons of tube worms, mollusks, and other organisms also become incorporated into the reef.

Scientific Classification - Corals are part of a group of organisms called Cnidarians. This group includes jellyfish, sea anemones, and sea fans and reef-building corals.

The reef-building corals can be identified by their stony skeletons made of calcium carbonate. A coral colony consists of thousands of individual coral animals, each similar in appearance to a small sea anemone with its base attached to a calcareous cup. Corals are armed with a ring of tentacles used to capture zooplankton from the surrounding water. Reef-building corals also contain symbiotic algae, called zooxanthellae, within their tissues. These single-cell algae have a mutualistic association with the coral hosts, a relationship that benefits both partners. The algae utilize carbon dioxide and nitrogen-based waste products released from the coral. In return, the algae perform photosynthesis, producing sugars and amino acids. These products are transported to the coral in support of its nutritional needs.

More about Coral Reefs


  • Include more than 50 species within 12 families
  • Live in wet saline habitats
  • Reproduce through viviparity
  • Refer to an entire plant community which includes mangrove species

The term "mangrove" refers to certain species of plant life or to the entire plant community which includes individual mangrove species. There are more than 50 species of mangroves distributed worldwide along tropical coastlines. The term "mangrove" does not refer to a specific taxonomic group of species, but to all halophytic (plants growing in saline soils) species of tropical trees and shrubs. This catchall, diverse group includes 12 families and more than 50 species. Although unrelated, all are adapted to life in wet soils, saline habitats, and periodic tidal submergence. Another use of the term "mangrove" includes the entire plant community including the individual mangrove species. Terms such as tidal forest, tidal swamp forest, mangrove community, mangrove forest, mangal, and mangrove swamp are synonymous with "mangrove".

More about Mangroves


Seagrasses are more closely related to the lilies rather than true grasses. There are over 50 temperate and tropical species of seagrass belonging to two families, with the most diversity occurring in the Indo-West Pacific region. Seagrasses are found on the bottom of protected bays, lagoons, and other shallow coastal waters. Although they are not true grasses, seagrasses appear grass-like with shoots of three to five leaf blades attached to a horizontal stem. They are attached to the bottom by thick roots and rhizomes, allowing seagrasses to live in areas with wave action and strong currents. Seagrasses can form large underwater meadows, spreading through the extension of the rhizome that produces new plants along the edges of the meadow. Flowering also occurs, producing seeds that are quickly dispersed via currents and tides.

Seagrass communities are important in tropical and temperate marine food webs, providing habitat for a diversity of marine animals. Some animals feed directly on the seagrass blades and roots while others scrape the epiphytes from the seagrass blades. Large predators also visit seagrass beds in search of prey.

More about Seagrasses

Back to Top