They sway in the current like multi-colored trees. Willowy feather plumes, sturdy sea rods, brilliant purple sea fans. Their undulations are so completely different than the solid rock-like forms of the stony corals, that it is hard to imagine that soft corals -- or Gorgonians -- are colonies of similar creatures. These beautiful coral colonies are abundant at the reef as well as forming virtual forests on some nearshore hardbottom areas, and even grace the bottoms of channels and canals.

Soft corals are often mistaken for plants. Rather than being formed of live tissues covering a rocky formation, they are anchored to the bottom by a holdfast, out of which grows a central flexible trunk that branches up into the water column. Although their skeletal structure is different, these corals are made up of colonies of polyps, as are hard corals. But instead of laying down a solid limestone skeletal structure, Gorgonians produce a protein skeleton. This skeleton is made up of a wood-like core that is surrounded by a softer layer called the rind. Coral polyps are embedded in this rind and extend their bodies through openings in order to feed.

Gorgonians are also known as octocorals, so named because the individual polyps have eight tentacles that they use to feed. If you look closely at the branches of a soft coral (sea rods are probably the most obvious), you may see the tiny tentacles of the individual polyps. Each of these tentacles is feathered, and the creature uses them to capture plankton floating in the current. Soft corals polyps are able to contract and expand, and this ability changes their appearance enormously. When the polyps are expanded, the colony appears soft and fuzzy. Contracted they look more like barren tree branches in winter.

One of the reasons that soft corals wave so splendidly in the current is that they orient themselves to take advantage of the movement of the water. By facing the prevailing surge or current, they are able to capture more food as it washes past them. This is why you'll often seen a group of purple sea fans facing the same direction and waving like a lace curtain in a breeze. Their flexible skeleton allows them to bend under the pressure of the flowing water.

These unique animal colonies bear a spectrum of colors. Many varieties enjoy a symbiotic relationship with the microalgae zooxanthellae. This algae, as with the stony corals, lives within the tissue of the coral polyp. And, as with the hard corals, the algae partners give a greenish or brown hue to the coral. Some Gorgonians sport their brightest color in their living tissues, others in their skeletal stalks. Colors range from greens and yellows to breathtaking reds and purples.

Although they look very different that hard corals, Gorgonians' needs are quite similar. They require clear, nutrient-free water, a constant temperature, and ample sunlight. They are vulnerable to many of the same threats that stony corals face: bacterial infections, bleaching, algal growth and sedimentation. Fortunately, if they succumb to any of these stresses, soft corals tend to grow back more quickly than their stony counterparts.

Next time you're out in the water, take a closer look at these amazing creatures and the animals that live on or around them. You might be rewarded with the sighting of a flamingo tongue, a tiny shelled creature that lives almost exclusively on sea fans. Just another reminder of how intricately linked all of these uniquely specialized animals are that make up the coral reef.

- Alyson Matley
Florida Keys National Marine Sanctuary
The Sounding Line