Key Biscayne National Park Underwater

Coral Reef

Coral Reef Fish

"In variety, in brilliance of color, in elegance of movement, the fishes may well compare with the most beautiful assemblage of birds in tropical climates," Louis Agassiz, 19^th-century French naturalist, wrote after visiting the Florida reefs. Reefs host the world’s most spectacular fish. Along Biscayne’s reefs are more than 200 types of fish. Some are impressive in size, others in color. Some seem grotesque, others dangerous – or are they? Many behave in bizarre, unexplainable ways, at least to humans. Few places on Earth match the diversity of life in the reefs’ underwater wilderness.

Dive into the undersea realm of the coral reefs, and you will discover a feast for the eyes. It is a living kaleidoscope of gaudy colors, bold patterns, intricate designs, and peculiar shapes. Alien, yet inviting, the life of the coral reefs excites and mystifies snorkelers and scientists alike.

Key  Biscayne Reef Builders

Among the most puzzling creatures are the corals. Early biologists suspected they were plants. But each coral – each brain, finger, or staghorn coral – is actually a colony of thousands of tiny, soft-bodied animals. These animals called polyps are relatives of the sea anemone and jellyfish. Rarely seen in the day, the polyps emerge from their hard, stony skeletons at night to feed, catching drifting plankton in their outstretched tentacles. These primitive, unassuming animals are the mighty master reef builders. The creation of one reef requires the effort of billions of individuals. Each extracts building material – calcium – from the sea and uses it to make itself a protective tube-shaped skeleton. Hundreds of these skeletons make a coral. Many corals, growing side by side and one on top of the other, form a reef.

Corals are very particular about where they build reefs. Like the offshore seas of Biscayne, the water must be the right temperature (no cooler than 68 degrees F), the right depth (no deeper than 200 feet), and be clean and well-lit. Such conditions exist along the Florida Keys in and south of Biscayne and in the Caribbean, and in other tropical oceans.

Coral Reefs: Undersea Metropolis

Coral reefs are the cities of the sea. In and around them live a huge, diverse population of fish and other marine creatures. Every hole, every crack is a home for something. Some inhabitants, such as the Christmas tree worm, live anchored to the coral. There is food to satisfy all tastes. Fish and flamingo tongues (snail-like mollusks) eat coral. Fish are food for other coral reef fish and, quite often, for seafood gourmets.

A Sea of Color

Imagine the most colorful scene you have ever seen – a field of wildflowers, glittering lights of a city at night, a desert sunset. Whatever it is, the dazzling spectrum displayed by reef fish will equal or surpass it. The range extends from the flamboyant – angelfish, wrasses, parrotfish, and neon gobies – to fish that seem drab and ordinary.

There is much spectacular about what role the colors play. The answer differs for each fish. An eye-grabbing wardrobe may serve as a kind of billboard, advertising a fish’s presence. Vividly colored wrasses attract other fish in this way so they can clean them of parasites and dead tissue, getting a meal in return. Multicolored bars, stripes, and splotches blur the outline of other fish, making it difficult for predators to see complex background. Some fish are masters of disguise. Many turn different colors at night, presumably to hide from nocturnal predators. The camouflaged moray eel blends in with its surroundings. Unsuspecting fish that swim too close often get caught between the eel’s powerful jaws and needle-sharp teeth.

A Montage of Motion

Morays are sedentary creatures, but most fish swim freely about the reefs. Some, like the solitary angelfish, move with deliberate grace. Others dart about in schools of thousands, moving with the precision of choreographed dancers. Each closeknit group offers protection to its members. Reef fish are noted for their eccentric behavior. One is the sharp-beaked parrotfish. It can be seen, and even heard, munching on a coral. Odd meal for a fish? Not really. Along with rock, the parrotfish is devouring algae and coral polyps.