The elegant and unique Gorgonians add an exciting feature to the ocean’s landscape!
The Gorgonians are soft coral colonies that are generally tree like. Though found in many areas of the ocean, those found in tropical and subtropical waters have the most diversified shapes. The distinctive forms of the Gorgonians include the beautiful sea fan, a dynamic sea whip or sea blade, or they can be bushy creating a sea rod resembling a soft sea spray.
Gorgonians are members of the Subclass Octocorallia. This group is called the Octocorals, and loosely referred to as soft corals. Like most Octocorals, Gorgonians are colonial sessile animals. Sessile means they are anchored to the substrate, and from there they can be either erect or encrusting. Gorgonians have a central stem that is tough, yet very flexible. It is covered with a living surface called a rind which is embedded with small polyps. The stem attaches to the substrate, with the delicate branches radiating outward.
Gorgonians are not recommended as a beginner’s coral. Yet although they are considered a more difficult coral to care for, they can thrive for a long time if provided with the proper environment. They must be anchored to the substrate and need a brisk water movement. Most are photosynthetic and so need light to survive, and most must be fed.
While many Leather Corals and Soft Corals make great beginner corals, there are hundreds of other different types of soft corals. Some unique Octocorals include the the Blue Coral, Mat Polyps like the Organ Pipe Coral and Green Star Polyps, and the Sea Pens. Each of these beautiful corals will have care requirements that are just as diverse as the animals they are; consequently not all soft corals are easy keepers. It is very important to learn about the species you are keeping for a successful reef aquarium.
For information about setting up a reef tank see:Reef Tanks – Mini-Reef Aquarium Basics
What are Gorgonians
The Gorgonians inhabit many areas of the oceans. Most are found in shallow coastal waters down to depths of 985 feet (300 m), with only a few living in deeper seas. The tropical Gorgonians were introduced into the saltwater aquarium trade in 1970, and specimens from the Caribbean were introduced in the 1980’s.
In its taxonomical structure, the Gorgonians belong to the Order Alcyonacea, which also consists of the true soft corals. This order, along with numerous others, is a member of the Subclass Octocorallia, known as the Octocorals. These are corals with eight-branched tentacles and eight septae in their polyp structure. Under the Alcyonacea order, the Gorgonians are further divided into three Suborders, Holaxonia, Scleraxonia, and Calcaxonia.
Like the majority of the Octocorals, Gorgonians, are colonial sessile animals. Sessile means they are anchored to the substrate, and from there they can be either erect or encrusting. Gorgonians differ from stony corals. The mass of a stony coral is primarily made up of a rigid calcareous skeleton, with living tissue growing on top. Gorgonians on the other hand are primarily composed of living tissue.
Gorgonians have a central stem that is tough, yet very flexible. It is covered with a living surface called a rind. The stem attaches to the substrate, with the delicate branches radiating outward. The suborder Holaxonia are composed of a fibrous protein substance, known as gorgonin, which is similar to the horn material of mammals. The common names, Gorgonian, Horn Coral or Horny Coral, are derived from this substance. Those in the suborder Scleraxonia are calcium based similar to other Octocorals.
Types of Gorgonians
Most Gorgonians are very colorful found in shades of yellow, orange, and red. The color can be permanent in those of the suborder Scleraxonia that incorporate pigmented sclerites within their structure.
Some Gorgonians that are most familiar include:
- Splendid Knotted Fan Coral Acabaria splendens
- Finger Sea Fan (Red Finger Coral, Yellow Finger Coral) Diodogorgia nodulifera
- Corky Sea Finger (Purple Corky Finger) Briareum asbestinum
- Pacific Encrusting Gorgonian Briareum stechei
- Encrusting Gorgonian Erythropodium caribaeorum
- Knobby Sea Rod Eunicea sp.
- Sea Fan Gorgonia sp.
- Red Gorgonian Leptogorgia chilensis (Synonym: Lophogorgia chilensis)
- Spiny Sea Fan Muricea sp.
- Purple Bush, Rough Sea Plume Muriceopsis flavida
- Sea Rod, Candelabrum Plexaura sp.
- Porous Sea Rod Pseudoplexaura sp.
- Sea Plume, Sea Feather Pseudopterogorgia sp.
- Purple Sea Blade, Angular Sea Whip Pterogorgia anceps
- Bushy Sea Rod Rumphella sp.
Though considered more difficult to care for, Gorgonians can thrive for a long time if provided with the proper environment. They must be anchored to the substrate. Most species need brisk but moderate water movement. They need good currents to help rid themselves of the waxy film that is secreted to rid themselves of algae. Surge devices or turbulent water flow is best. Many gorgonians are photosynthetic and so need light to survive. Others that grow at great depths or in shaded areas don’t require light. Gorgonians usually must be fed to survive in the aquarium.
Care of Photosynthetic Gorgonians:
Those that are photosynthetic need good lighting as well as strong currents. These derive much of their nutrition from a marine algae known as zoozanthellae, contained in their tissue,. Although most are not accustomed to the very strong lights produced by metal halide, it is said that they will eventually adjust and grow faster because of it. Some photosynthetic Gorgonians can be fed while others cannot. In either case photosynthetic gorgonians don’t need to be fed in order to survive.
Care of Non-Photosynthetic Gorgonians:
For those that need to be fed, feed them at least once a week. Some Gorgonians like the Finger Sea Fan Diodogorgia nodulifera need a much more steady food supply, with several feedings a day being optimal. Feed detritus, brine shrimp, Daphnia, Cyclops, or pulverized flake food, shrimp or clams. Sometimes you can stir up the gravel slightly in order to mix detritus in the water for feeding the detritus eating species.
What Are Gorgonians – Gorgonians, Sea Fans, Sea Whips
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