The Green Star Polyps Pachyclavularia violacea is a striking beauty, and very robust. With a perfect complement of color, it has a bright purple to reddish colored mat and very green, yellow, or light green tentacles. Rather than the feathery tentacles seen on encrusting gorgonians, it has 8 bold tentacles that are thin and smooth. They surround a center opening, or mouth, that is often another contrasting color adding an additional spark to these already attractive mat polyps.
Getting a specimen with green tentacles and a purple base makes for quite a glow under actinic lighting. Yet there are also pretty color morphs, like the Brown Star Polyps pictured under the description below. Other colors include those with white or yellow polyps. The center, or mouth, is often a contrasting color, giving these mat polyps an attractive appearance. Various names these corals are known for include Daisy Polyps, Star Polyps, Mat Polyps, Starburst Polyps, and Eight Tentacle Polyps.
The true Star Polyps are mat polyps of the Pachyclavularia genus in the Tubiporidae family. They have a bright purple to reddish colored mat and very green, yellow, or light green tentacles. Another well-known and colorful member of this family is the Organ Pipe Coral Tubipora musica.
Identifying the Green Star Polyps is very easy, but there are a couple of other genera like Briareum, Clavularia, and Anthelia that they can be confused with. Pachyclavularia and Briareum are the two genera usually reputed as the “encrusting gorgonians” or “star polyps”. The Green Star Polyps do form flat stolons, or mats. But their mats are quite irregularly layered and rubbery feeling, and flatter than Briareum corals like the Pacific Encrusting Gorgonian B. stechei. The polyps residing within their mat are also less feather-like in comparison, a good example is those seen on the Corky Sea Finger B. asbestinum.
Through an early mis-identification, the Green Star Polyps have also been incorrectly called Clavularia viridis. However they lack the lush side branches, or pinnules, of the Clavularia genus. From a description of Clavularia, you will quickly see that Star Polyps do not fit the Clavularia “glove”. A good example can be seen in the Palm Tree Polyps Clavularia viridis.
The Pachyclavularia genus is very easy to care for. They are very robust, will eagerly spread, and are simple to propagate. Their main requirement is moderate to strong turbulent water flow. They are happy with fluorescent lighting, and providing actinic lighting can bring out any iridescent colors. It may be helpful to keep the colony on a rock that isn’t connected to any of the rock work, or they may spread and take over some corals. This is a great beginners coral and a wonderful candidate for those who want to try propagation techniques.
To learn more about these fascinating mat polyps see:
What Are Octocorals?
The Green Star Polyp, or as many call it, GSP, are easy to care for. They are best kept in a 50 gallon tank or more and they like bright lighting, however they can tolerate less light with supplemental feedings. They like moderate to high water movement, and will not do well in slower waters. Lysmata or Saron Shrimp will feed on them and certain species of algae will grow over them.
Order: Stolonifera – Mat Polyps
Species: Pachyclavularia (Briareum) violacea
Distribution / Background
Soft Coral Information: The Pachyclavularia genus was described by Roule in 1908. True Star Polyps are mat polyps of the Pachyclavularia genus, members of the Family Tubiporidae. They have a bright purple to reddish colored mat and very green, yellow, or light green tentacles. Some common names they are known by are Green Star Polyps, Brown Star Polyps, Daisy Polyps, Star Polyps, Mat Polyps, Starburst Polyps, and Eight Tentacle Polyps.
The scientific classification of the Green Star Polyps has a long history of confusion. In his book “Aquarium Corals, Selection, Husbandry and Natural History”, author Eric H. Borneman describes the sequence of events. The confusion started with Quoy and Gainard describing both C. violacea and C. viridis in 1863, and then it was again described by HIckson in 1894. This lead to a deternimation that there were problems with its identity. In a broad stroke, this and a few other poorly defined genera were then just lumped into the Clavularia genus. This has been somewhat sorted out since, and the Green Star Polyps are no longer considered a Clavularia species. However the result was that in some literature it was then called C. violacea, and this unfortunate misnomer still shows up occasionally today.
Today the Green Star Polyps is generally considered to be of the Pachyclavularia genus, though the scientific name P. violacea itself is not a valid species name. There are also some experts who treat the Pachyclavularia genus and the encrusting gorgonians of the Briareum genus as synonymous, thus the name Briareum violacea also shows up.. The Pachyclavularia genus may eventually be reclassified as a member of the Briareidae family, yet there appear to be important differences.
The Pachyclavularia is generally distinguished by a brighter purple to reddish color mat and very green, yellow or light green tentacles, while the Briareum species generally have a brown or tan base. Unlike the Pachyclavularia genus, the Briareum species can shed a mucus ‘sheet’ and they also form upright finger-like protrusions from their base while the Pachyclavularia species can only seem to create folds in the mat. So it remains to be seen what scientific classification will ultimately be deternined as correct for the Green Star Polyps.
Where Pachyclavularia Corals Are Found: The Pachyclavularia genus are found in the Indo-Pacific oceans.
Pachyclavularia Coral Habitat: The Pachyclavularia genus are found along upper reef edges and lagoons, in shallow waters to moderate depths. They are most common on inshore reefs and reef flats where there is a more moderate water flow.
The Pachyclavularia genus is not on the IUCN Red List for Endangered Species.
What do Pachyclavularia Corals look like: The Green Star Polyps Pachyclavularia violacea is an encrusting mat-like coral.
Courtesy Carrie McBirney
Green Star Polyps form flat stolons, or mats, that are quite irregularly layered and rubbery feeling. The stolon is connected forming a mesh-like structure, with all the polyps being housed in tubular calyces.
The popular Green Star Polyps has a bright purple to reddish colored mat and very green, yellow, or light green tentacles. There are 8 bold tentacles to a polyp that are thin and smooth. The tentacles surround a center opening, or mouth, that is often another contrasting color. Other color morphs include those with brown, white, or yellow polyps. Besides the Green Star Polyps, the Brown Star Polyps shown here is one of the most common color forms.
The polyps are generally expanded unless an outside stimuli disturbs them, then they can retract fully. They are aggressive and can cover over other corals, but are also at risk of being stung. Other nearby corals with potent stings may prevent them from expanding their polyps. They can grow about 1″ (2.54 cm) per month in optimal conditions.
Difficulty of Care
Soft Coral Care: The Green Star Polyps P. violacea is very easy to care for and the only requirement is moderate to strong turbulent water flow to remove detritus, and helps with optimal polyp expansion. Most light is acceptable, and providing actinic lighting can bring out any iridescent colors. Metal halides may be too strong, which will be evident it the coral color becomes pale or bleached out.
The Green Star Polyps are fast spreading, aggressive, and adaptable to all areas of the aquarium. This hardy growth can be a bonus when used as a decorative cover for particular areas in the tank. Otherwise, It may be helpful to keep the colony on a rock that isn’t connected to any of the rock work, or they may spread and take over some corals.
Foods / Feeding
Soft Coral Feeding: In the wild, Pachyclavularia corals have developed several feeding strategies. They can absorb dissolved organic matter from the water column, and have a symbiotic relationship with a marine algae known as zooxanthellae, where they also receive some of their nutrients.
In captivity, the Green Star Polyps have not been observed actively feeding. Rather they will use light and their zooxanthellae for a food source, and will absorb micro particles from the water.
Stable tank conditions are needed to keep the Pachyclavularia genus. Doing water changes of 20% a month or 10% biweekly is needed, although it is suggested that doing 5% water changes once a week will replenish many of the needed additives. Calcium and other trace elements can be added to maintain proper levels for good growth.
There are some cautions to be aware of with additves. Their have been reports of the Pachyclavularia genus having an adverse reaction to some iodine additions, “…specifically in the form of Lugol’s solution” (Eric Borneman). They can also be sensitive to the aluninum oxide in some phosphate removing sponges.
Suggested levels for Pachyclavularia species are:
- Calcium: 400 – 450 ppm
- Alkalinity: 3.2 – 4.8 MEQ/L (8 to 11 dKh – 10 is recommended)
- Phosphates: 0, zero.
- Magnesium: 1200 – 1350 ppm. (Magnesium makes calcium available, so if your calcium is low, check your magnesium levels before adding any more calcium.)
- Strontium: 8 – 10
|Quick Reference Chart
A typical live rock/reef environment is what is needed for your Green Star Polyps, along with some fish for organic matter production. The P. violacea will rapidly spread, so It may be helpful to keep the colony on a rock that isn’t connected to any of the rock work, or they may spread and take over some corals
Provide proper lighting and water movement. They are adaptable to most lighting, but metal halides may be too strong, which will be evident it the coral color becomes pale or bleached out. Providing actinic lighting can bring out any iridescent colors. A good water flow is essential, not only to remove detritus but also helps with optimal polyp expansion. This is an aggressive species that will quickly cover other corals and even itself.
- Minimum Tank Size / Length:50 gallon (190 L) or larger
- Marine Lighting: Moderate to high
- Temperature: 72Â° – 83Â° F (22Â° – 28Â° C)
- Salinity / Specific Gravity: 1.023 – 1.025
- Water Movement: Moderate and turbid
- Water Region: All areas of the aquarium
Compatibility and Social Behaviors
The Green Star Polyps is very aggressive in that it will grow over other corals and even itself, so containment is essential. Isolating them with sand, away from the main rock can help, as well as regular fragging. They can be put on the sand, away from the main rock work and they will stay put. Putting it among the rock work will encourage growth onto the rocks and then over other corals.
Though they are aggressive and can quickly cover over other corals, they are also at risk of being stung. Other nearby corals with potent stings may prevent them from expanding their polyps.
Sex – Sexual differences
No sexual difference in appearance is known.
Breeding and Reproduction
The Pachyclavularia genus will form daughter polyps from the edge of their mat. Some species will form planulae with their young brooding on the surface of the colony.
Propagation is easy, simply cut off pieces of a mat and glue them, or better yet, rubber band them to a rock or plug. You can also train them to spread onto rubble that can be easily snipped apart as needed. In sheet form they can be adhered to all sorts of surfaces like the aquarium glass and overflows, to create a living decorative cover.
The Pachyclavularia genus is hardy and very easy to care for. However they are susceptible to detritus collecting, filamentous algae and slime algae, and even aiptasia anemones growing in-between their stalks. They need water that is at least moderate and turbulent enough to keep them blown them off on a regular basis. These pests may have to be scrubbed off of the calyces and stolon mat on occasion, for the health of the colony, possibly for its survival in extreme cases. Sometimes infested areas may have to be cut off and then siphon or scrap the remaining coral. Healthy tissue should soon regrow.
Soft Corals for Sale: The Green Star Polyps P. violacea is easy to find at pet shops and on line. Online they can run about $10.00 USD and up, depending on size and/or color..
- Animal-World References: Marine and Reef
- Eric Borneman, Aquarium Corals : Selection, Husbandry, and Natural History , TFH Publications, 2001
- Anthony Calfo, Book of Coral Propagation, Volume 1 Edition 2: Reef Gardening for Aquarists, Reading Trees; 2nd edition, 2007
- Harry Erhardt and Horst Moosleitner, Marine Atlas Volume 2, Invertebrates (Baensch Marine Atlas), Mergus Verlag GmbH, Revised edition, 2005
- Bob Goemans, Green Star Polyps or Starburst, Animal Library, Saltwatercorner.com
Featured Image Credit: DiGUM, Shutterstock