FLORIDA KEYS -- The Florida Keys are paralleled by continental America's only living coral barrier reef, which contains an incredible diversity of life. But too often, an excited visitor kicks right past some of the most interesting critters - the tiny animals that inhabit the nooks and crannies of the reef, the hatchlings that form schools and circle coral mounds and outcroppings, and the burrow-digging dwellers of the sea floor.

On top of boulder and brain corals, one-inch-tall Christmas tree worms stand in the current catching a meal. Technically tube-worms, these tiny animals snap back into their calcareous tube, which is embedded in the coral, when approached. But hover motionlessly for a minute or two and they often reappear.

The "Christmas trees" are actually feeding extensions, called radioles, from the worm's body.

The feather duster worm is a bit larger than its tree-shaped cousin. This worm's radioles are shaped like the matching halves of an oval.

Peek into a small crevice along the reef and a banded coral shrimp is likely to greet you. This 1- to-1.5-inch shrimp has red and white bands along its body and claws. The shrimp waves its (relatively) long white hair-like antennae to attract a fish.

The banded coral shrimp is a cleaner shrimp. It picks food particles and parasites from the mouth and head area of a fish that has come to the "cleaning station."

A bare hand extended toward the shrimp sometimes brings the tiny worker out of its protective cover in the reef to clean the fingers. Banded coral shrimp are also found along the rails and gunwales of artificial reefs in the Keys.

Another dozen or so species of tiny shrimp inhabit the reef, standing on anemones and turtle grass, waiting for a cleaning job or passing prey.

Divers often see gorgonians, or sea fans, and enjoy the gentle sway of these purple corals. A close look can reveal a life-and-death struggle.

The pretty little flamingo tongue is an under one-inch-long gluttonous eater of gorgonians. It has a cream-white mantle, an outer skin, with irregularly-shaped black-outlined orange spots. Gently touch the mantle and the tiny mollusk draws its skin back into its shell, revealing a cream-white shell that sometimes shows hints of pink.

One of the giants of the close-up world on Keys reefs is the blunt-spined brittle star. Its .75- to 1.25-inch body centers five 4- to 6-inch arms. Each arm has short, blunt spines.

Brittle stars are often found on the underside of loose rocks or concrete block bottoms of destroyed lobster traps. The quick-moving star is usually quite willing to skitter across an outstretched palm.

A lonely coral mound becomes a self-contained universe with hatchlings and juveniles from a variety of tropical reef fish species schooling about. Shrimp and arrow crabs can be seen moseying around the holes and crevices.

Out on the sand, just a few kicks from the reef, the yellowhead jawfish acts as a one-fish excavating crew. The jawfish digs itself a safe burrow by carrying out sand and pebbles in its mouth. When threatened, the jawfish zips into its burrow tail first, but when approached slowly, it will hover above its escape to greet the cautious diver.

Like a scarf flowing in a breeze, the long dorsal fin of the juvenile spotted drum creates a degree of elegance for the 2- to 4-inch fish. The fin, actually a defense mechanism making the fish appear much larger than it is, has a black stripe that continues along the drum's body and tail, completing the illusion.

A black spot on its nose, and black bars across its head, make the juvenile spotted drum easy to recognize by slow-moving, sharp-eyed divers.

With so much to see on Keys reefs, there's a natural tendency to cover a lot of territory. But a slow cruise along the reef shows that beautiful sights also come in small packages.

For more information on the Keys peruse this Web site or call 1-800-FLA-KEYS, toll-free in the U.S. and Canada.