Of the thousands of species of gorgonians that are found throughout the world’s oceans and seas, there are many different families. One such family belongs to the order Alcyonacea – a name which has replaced the previous title of “Gorgonacea.” Sessile colonial cnidarians found throughout the world, primarily in warmer waters, gorgonians are close relatives of various coral species, and are also relatives of sea pens and jellyfish, among the some 11,000 documented cnidarian species. Beautiful members of the animal kingdom, they are an important part of the ecosystem. Let’s take a closer look.
Gorgonians: The Basics
Structured in fan shapes and long whip formations at times, gorgonians are groups of individual polyps which live together in colonies that sometimes take on the shape of bushes, and sometimes encrust themselves over rocks, corals, and wrecks. Often in bright colors such as yellow, orange, red, or purple, they are considered to be soft corals. Although many gorgonians, particularly those found in deep, cold environments, are filter feeders, others are photosynthetic and can be found in shallow reef environments. Some anchor themselves in sand or mud, while others prefer hard substrate.
Each gorgonian polyp has eight tentacles, which it extends to feed on plankton and other particulate matter that passes in the current. When photosynthetic species consume algae, the algae flourish inside the polyp structures, providing nutrition and giving the gorgonians a brownish or greenish tinge. Those with the brightest colors are rarely found in shallow water.
In addition to differences in color which provide clues as to what the gorgonian colony is feeding on, differences in shape provide information. A gorgonian’s appearance, including its size and shape, is highly correlated with its location, with taller, thinner, and less flexible colonies living in deep calm water, while those which are more flexible and wider tend to populate areas with swifter currents and less depth.
Other creatures rely on the branches of gorgonian colonies for shelter. One of the most notable species is the pygmy seahorse, which relies on its host not only for protection from the elements, but for camouflage. Brittle stars, hydrozoa such as jellyfish, and bryozoans, often microscopic filter feeders, depend on gorgonians as well.
While gorgonians do not possess the same calcium carbonate skeletons as reef building corals, they do have skeletons which are formed of the remains of individual polyp spicules, which fuse and accumulate over time. Researchers rely on skeletal remains to provide clues about the world’s changing climate and water composition via paleoclimatology and paleoceanography; different species grow at various rates, but can be correlated with both climatic and seasonal variation, along with chemical changes.
Where to View Gorgonians
As there are about 500 different gorgonian species known to science, it is possible to encounter different types of colonies in many different and often unexpected places. Divers in Florida, the West Indies, and Bermuda can often find shallow water examples, as can divers in the Caribbean and Indo-Pacific regions.
In colder waters, such as in the area off Canada’s British Columbia down to northern California, beautiful red gorgonians thrive at depths between 170 and 195 feet; well out of the reach of recreational divers. Often found along walls and anchored to deep rock formations, they are sometimes accompanied by strawberry anemones and sponges, and create important habitats for additional life forms to thrive. At the bottom of British Columbia’s Nootka Sound, for example, there is a massive garden of gorgonians that takes serious planning and effort to explore.
Much more resilient than hard corals, gorgonians are still sensitive organisms which should not be touched or disturbed. Some shallow water species, particularly those that are more colorful and rare, are subject to victimization by the aquarium trade; luckily, aquaculture specialists are now growing captive gorgonians rather than collecting them from sensitive environments. It is fantastic to know that many of these species are still going strong; with continued education and purposeful focus on improving the world’s environment, we can help them and other marine life thrive for generations to come.