Size: Up to 6 feet (2 m) high and 5 feet (1.5 m) wide.
Range: In Atlantic Ocean from Bermuda south to Curacao.
These large coral colonies are easy to recognize because of their fan shape. A flexible, horny substance called gorgonin forms this coral's central skeleton, which supports all branches of the colony. Living tissues form a layer over the skeleton's entire surface.
More than a million microscopic algae called zooxanthellae are found in a square centimeter of coral tissue. The algae make food for the coral through the process of photosynthesis. The algae also generate the coral's color. Sea fans appear in shades of red, yellow, or orange.
Sea fans typically grow across the current so that their polyps can spread out their tentacles to form a net for catching microscopic plants (plankton). There are about 500 species of Gorgonia. The species shown here is found in the shallow waters of all oceans, but is especially abundant along the Atlantic coasts of Florida, Bermuda, and the West Indies.
Faculty Research: Dr. Nancy Targett
Dr. Targett's research integrates chemistry and biology, specifically focusing on better understanding chemistry's role in complex relationships among reef dwellers. During field work in the Caribbean a few years ago, she noticed a large proliferation of brown algae. She wondered why the plant-eating fish (herbivores) which are so abundant in the tropics were avoiding brown algae. In search of an explanation, she turned to a large body of work done in terrestrial and marine environments that suggested the algae may have been employing tannins as a chemical-defense mechanism - something that would render the plants toxic, bad-tasting, or undigestible, thus causing fish to avoid eating them.
Upon analyzing the algae, Dr. Targett found that many of the plants contain large amounts of a class of chemicals called phlorotannins. Terrestrial analogs of these chemicals are among the most common employed by plants to protect themselves from being eaten. Until her work, the compounds were not known to occur in tropical brown algae.
In further research, she and her students have found that these chemical compounds don't always occur in the same concentration in brown algae. Interestingly, it appears that extrinsic environmental factors such as nutrients, light, and herbivory influence an alga's "decision" about whether to put its energy into growing or into defending itself from fish predators. For example, in overenriched, or "eutrophic," waters, the algae produce less phlorotannins and put more of their energy into growth. This can spell disaster for corals, which can be choked out by the algae.
As a result of this research, Dr. Targett and her team hope to contribute to the ability to predict where problems may occur on coral reefs due to nutrient runoff and other human impacts.
