The snook (Centropomus undeimalis) is popular in the recreational fishing industry of the Florida Keys. This fish is usually found click image for more... (photo: Bob Care - Florida Keys NMS)

The Florida horse conch (Pleuroploca gigantea) is the Florida state shell. It usually lives in the seagrass beds and around the patch reefs inshore of the main reef. (photo: Heather Dine - Florida Keys NMS)

The spiny lobster (Panulirus guttatus ) is a reef dwelling organism that hides in and under the coral formations by day and forages in the click image for more... (photo: Paige Gill - Florida Keys NMS)

Seagrass is one of the most productive and important ecosystems in the Keys and it is being destroyed at an alarming rate. Much of this damage click image for more...(photo: Harold Hudson)

The Florida Keys National Marine Sanctuary is visited by several marine mammal species, including the endangered West Indian manateeclick image for more... (photo: Laurel Canty-Ehrlich)

Boulder and massive corals, like this boulder star coral (Montastrea annularis), are the "builders" of the reef. A coral head is a colony of small animals called polyps. Polyps the size of a pencil eraser build an external ...click image for more... (photo: William Harrington)

Elkhorn coral (Acropora palmata) is a branching coral. Branching corals grow in the shallow areas of the reef crest and serve to break click image for more... (photo: Paige Gill - Florida Keys NMS)

Pillar coral (Dendrogyra cylindrus), although beautiful, is rare in the Florida Keys. Pillar coral is unusual in that its polyps are usually extended click image for more...(photo: Harold Hudson)

Corals are large colonies of small animals called polyps. These polyps reside within a cup-like calcium carbonate skeleton. click image for more... (photo: Florida Keys NMS)

In addition to the hard corals, there are a variety of soft corals like this common sea fan (Gorgonia ventalina). The calcium carbonate skeleton of soft corals is located within their bodies, allowing them to move with the wave action. click image for more... (photo: Larry Zettwoch)

Often mistaken for plants, soft corals including the deep water sea fan (Iciligorgia schrammi), and the giant slit-pore sea rod (Plexaurella nutans), attach themselves to a hard substrate and slowly move with the natural wave action.click image for more...(photo: Florida Keys NMS)

There are an increasing number of diseases that which affect coral. Black band disease, shown here, is a cyanobacteria click image for more... (photo: Paige Gill - Florida Keys NMS)

Coral bleaching is a growing phenomenon for coral reefs globally. It is caused by the expulsion of the symbiotic algae, zooxanthelle, from the coral polyps. The zooxanthelle gives the coral its color and is also the source of most of the coral's nutrients. Coral click image for more...(photo: Florida Keys NMS)

There are many small invertebrates on the reef, like this banded coral shrimp (Stenopus hispidus), that are often click image for more... (photo: Joseph Feingold - Florida Keys NMS)

The Christmas tree worm (Spirobranchus giganteus) can often be found on coral heads throughout the Florida Keys.Their radioles, click image for more... (photo: Florida Keys NMS)

The moray eels, like this goldentail moray (Gymnothorax minliaris), are often feared because of their continuous motion of click image for more.. (photo: Steve Kipnis - Florida Keys NMS)

The four-eye butterflyfish (Chaetodon capistratus) is one of hundreds of fish species which inhabit the reef environment of click image for more... (photo: Chris Huss - Florida Keys NMS)

The queen angelfish (Holacantus ciliaris) is one of the most dynamic and beautiful reef residents. Commonly seen, it is one of divers' favorite species. (photo: Chris Huss - Florida Keys NMS)

Minnows, the common name for a variety of very small silvery fish, can often be seen schooling around the reef. These fish school to confuse their predators. In large masses it is very hard to identify one fish to attack, therefore the entire group evades being eaten as the predators go in search of easier prey. (photo: Paige Gill - Florida Keys NMS)

The yellowtail snapper (Ocyurus chrysurus), abundant in the waters of the Keys, is the center of a large commercial and recreational fishing industry. Found in the water column above the reef, this is usually one of the first species a diver or snorkeler will see upon entering the water. (photo: Jim Raymont - Florida Keys NMS)

The spotted eagle ray (Aetobatus narinari), one of three rays commonly seen in the Florida Keys, is a majestic animal that can be seen throughout the Caribbean click image for more... (photo: Mike White - Florida Keys NMS)