One of the divers’ favorite types of coral is the sea fan. A mature sea fan is a strikingly beautiful, majestic coral colony. The fan is a close relative to the soft corals, but because of its structure, it is designated as “horny coral.” This type of coral has polyps embedded in a soft layer of tissue that surrounds an internal, woodlike stalk. This stalk contains gorgonin (another common name for the sea fan is gorgonian), a protein resembling keratin, which is used in the biological production of fingernails, hair, and hooves.

The trunk of these fans is often very thick, strong, and rigid. As the branches reach outward to their extremities (often several feet), they become more flexible, gently waving in strong currents, which bring them the small organisms upon which they thrive.

The sea fan ranges in color from brown, gold, and orange to purple and brilliant red. It is particularly beautiful when the delicate-appearing polyps emerge to feed and completely cover the branches with their graceful featherlike tentacles.

[Pictures on page 26]

Top: Scarlet sea fan

Bottom: Gold sea fan