Animal-World > Aquarium Coral Reefs > Stony Corals SPS > Boulder Coral - Porites cylindrica

Jeweled Finger Coral

Finger Coral, Jewel Coral, Cylindrical Porous Coral

Jeweled Finger Coral, Porites cylindrica, also known as Finger Coral, Jewel Coral, and Cylindrical Porous CoralPorites cylindricaPhoto © Animal-World: Courtesy David Brough

   The Jeweled Finger Coral has the appearance of hundreds of little jewels across its surface!

   The corallites of the Jeweled Finger Coral Porites cylindrica add an element of sparkle to the reef aquarium. This is because they are covered with many corallites that are very small, and each corallite has 10 tiny septa. It is the abundance of septa that give it the appearance of having been sprinkled with jewels all across the surface. They come in many attractive colors including green, blue, golden yellow, yellow, purple, and pink. These colors can be very vivid, and for many specimens the color will be brought out under high intensity lighting.

   In the wild, the Porites genus forms some of the largest coral colonies. They can reach massive proportions, with some growths reaching about 26 feet (8 m) in height. They are some of the longest lived species on earth. Based on their rate of growth, it is estimated that some of these large colonies can be close to 1000 years old. This is not a challenge for the reef keeper however, because they are very slow growing, averaging only 1/3 of an inch (9 mm) a year.

   The Jewel Coral, also known as the Cylindrical Finger Coral, grows in finger like projections that can fuse at the tips. They are found on back reefs and lagoons, in shallow water that is exposed with the tides. Very high lighting and strong, turbid water movement is needed.

   P. cylindrica can be difficult to care for, but once it is acclimated can be very hardy. You will know if your lighting is inadequate, because their bright yellow color will fade to golden brown or mustard. The Jeweled Finger Coral is best kept in a shallow display to best provide high light and fast water movement. The Porites genus has been propagated in captivity, and some beautiful captive grown specimens are available.


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Scientific name    Family: Poritidae
   Species: Porites cylindrica

Distribution / Background    Porites Coral Information: The Porites genus was described by Link in 1807, with the Jeweled Finger Coral Porites cylindrica described by Dana in 1846. There are approximately 122 nominal species in the Porites genus, but it is still unknown how many of these are true species. The 16 species found in Australian waters are considered true species. Porites species have proven difficult to classify as individual species because of their minute calices. Some common names these corals are know for are Finger Coral, Jeweled Coral, Christmas Tree Worm Rock, Jeweled Finger Coral, Plating Jewel Coral, Jeweled Finger Coral, and Porites Coral. Some of the captive grown Porites have aquacultured names like Canary porites Coral P. cylindrica, Limited Edition Mike Paletta's Purple Porites, and Amethyst Porites P. annae.

   Where Porites Corals Are Found: The Porites genus are found in most of the tropical oceans and seas of the world.

   Porites Coral Habitat: Porites genus are found in a wide range of habitats. They inhabit most reef environments, from lagoons to reef fronts as well as at the base of coral mounts and in sandy substrates that can be sloping or flat. The water is usually very turbid with a high current. Some species have also been found surviving in lower salinity.

Status   The Porites cylindrica is listed on the IUCN Red List of Endangered Species as Near Threatened (NT).

Description    What do Porites Corals look like: The skeletons of the Porites genus are lightweight and porous. They have multiple growth forms that include flat colonies that are encrusting, flat leaf-like sheets, massive colonies that are dome shaped when large, and branching colonies. Colonies can grow quite large in size and some species can have several of the growth characteristics in one colony, as their growth formations are affected by water flow.

   Colonies of Porites can reach 26 feet (8m) in height and can be over 16 feet (5 m) in diameter. They are very slow at expanding, only growing 1/3 of an inch (9 mm) a year. Some colonies in the ocean that are estimated at over 1000 years old. Porites will often shed a mucous layer during the time of a full moon to rid themselves of waste, debris, and algae.

   The Porites genus corallites are small, submerged, and filled with septa. They are often confused with the Montipora corals as they both have corallites that are extremely small. However Porites have many differences in growth form, and their corallites are usually larger and more compact than those of the Montipora corals. The Montipora corals also lack the same type of septa.

   The Jewel Finger Coral P. cylindrica grows in finger like projections that can fuse at the tips. Hence additional common names including the Cylindrical Finger Coral, Jewel Coral, and Finger Coral. The abundance of septa the Porites genus have give the corals a jeweled appearance, as if jewels were embedded across the surface. The colors of Jewel Corals can be green, blue, mustard, yellow, purple, pink, as well as muted versions of these colors.

Difficulty of Care    Porites Coral Care: The Jeweled Finger Coral Porites cylindrica can be difficult to care for, but once it is acclimated can be very hardy. The species that come connected to your live rock tend to be the hardy species whose tentacles are out day and night while the harder to care for species can have tentacles out at night only, or during the day only.

   Porites often shed their outer surface layer to rid themselves of wastes and algae. It is actually done around the same time as the full moon. This waste may be removed to avoid fouling the water in smaller systems.

Foods / Feeding    Porites Coral Feeding: In the wild, small polyp stony (SPS) corals have developed several feeding strategies. Through a symbiotic relationship with a marine algae, known as zooxanthellae, they receive the majority of their nutrients. They also capture planktonic organisms and microscopic food particles from the water column and can absorb dissolved organic matter. The small tentacles of the Porites species however, make capturing planktonic foods less viable than for other SPS corals.

   In captivity, they do best in well-feed reef tanks. Small polyp stony (SPS) corals gets much of their nutrition from the zooxanthellae that lives in their tissues, and organic matter in the water. The Porites corals are generally supported by high lighting and small organics release into the water column, but may benefit from liquid coral foods or planktonic liquid preparations.

Aquarium Care   Pristine tank conditions are typically needed to keep all SPS corals. Keep the nitrate levels low, and maintaining calcium and alkalinity levels. Typically you can do water changes of 20% a month, 10% biweekly or 5% weekly. It has been noted that 5% weekly water changes replenish many of the needed additives. With higher concentrations of coral with calcareous skeletons, there may be a need put in additional additives to maintain proper levels for good growth.

   Suggested levels for Porites species are:

  • Calcium:  400 to 450 ppm (closer to 450). If the coral does not have enough calcium, it will not grow.
  • Alkalinity:  3.2 TO 4.8 MEQ/L (8 to 11 dKh - 10 is recommended)
  • Phosphates:  0, zero. Phosphates are the worst of all and all corals hate them.
  • Magnesium:  12000-1350. Magnesium makes calcium available, so if your calcium is low, check your magnesium levels before adding any more calcium.
  • Strontium:  8 - 10

Aquarium Parameters

   A well-feed live rock/reef environment is what is needed for your Jeweled Finger Coral, along with some fish for organic matter production. A mature tank is recommended.

Quick Reference Chart
Lighting: Prefers Low Lighting Levels Prefers Medium Lighting Levels Prefers High Lighting Levels
Water Flow: Prefers Low Water Flow Levels Prefers Medium Water Flow Levels Prefers High Water Flow Levels
Temperament: Peaceful Temperament Semi-Aggressive Temperament Aggressive Temperament

   Like other Porites, the Jeweled Finger Coral is best kept in a shallow display with high light and fast water movement. House them with fish and stir up the substrate to release organics into the water column. Make sure that no other corals can come in contact with your Porites. The Jeweled Finger Coral is not aggressive, but position it with plenty of room between it and other corals for its protection.

  • Minimum Tank Size / Length: 20 gallons (75 L) or larger
  • Marine Lighting: High
  • Temperature: 72° - 80° F (22° - 27° C)
  • Salinity / Specific Gravity: 1.023 - 1.025
  • Water Movement: Very strong and turbulent
  • Water Region: Top of the aquarium

Compatibility and Social Behaviors   Porites are not aggressive and plenty of space should be given between them and other corals. These are perhaps some of the most submissive corals, but they are also very adaptable. They can often survive attacks from other corals, growing and re-calcifying even if portions of their skeleton are dead.

Sex - Sexual differences    Colonies are either male or female, yet there are no visible differences to the outward appearance.

Breeding and Reproduction   The small polyp stony (SPS) corals are male and female and can reproduce both sexually and asexually. In the wild, for most of the Portites genus, sexual reproduction is done internally. These corals have male and female colonies, a trait they share with the Goniopora genus. The Porites genus male colonies release free-swimming sperm that the female colonies absorb. The female polyps brood the planulae in the body cavity rather than releasing eggs into the water column. They release the mature larvae when their development has been completed. They must rely on free swimming sperm released from the male colony to reach them. Some female species will release egg bundles into the water to meet up with sperm from male colonies, but there only a few that reproduce this way. In the wild small polyp stony (SPS) corals also spread asexually, from breakage due to storms and fragmentation.

   Propagating Porites corals is done by breaking the coral. Leverage the coral against a hard surface, then use a chisel, plastic pliers, hard table edge, or some even drop it on the floor to obtain frags. For some species you may want to glue the frag to a plug or rock, using the 2-part epoxy or underwater putties. Gloves are suggested. Give the frag ample water flow. They do not grow quickly.

Potential Problems    The Porites cylindrica. are hard corals that once established, may not be susceptible to many diseases. But they can still get the same illnesses that any other small polyp stony (SPS) coral can get under poor conditions, or when they first arrive. There are several ailments these corals are subject to including bleaching, black-band disease, white-band disease, algae encroachment, and others. Here are some of the ailments and suggested treatments:

  • Black-band disease: To prevent necrosis, and fight black band disease, the corals can be treated with Tetracycline at 10 mg per quart/liter according to one author.
  • Bleaching: This is the mass expulsion of zooxanthellae. Stress can trigger it and it generally will take the aquarist by surprise. The coral is still alive with slightly pigmented tissue. (will not be pure white) A suggestion is to turn down your lights so the zooxanthellae does not spin out of control and right out of your coral. Otherwise, once bleaching occurs, it has a 50/50 chance of complete healing. They will be prone to illness at this time.
  • Parasitic Animals: There is a Nudibranch, Phestilla lugubris that will feed on your Porites genus. Symptoms are patches of discolored polyps or tentacles not extended.

   if your stony coral has any kind of tissue recession, you may be able to remove the unhealthy part. Just make sure you cut into some of the healthy part also, to be sure there is no disease encroaching on the healthy tissue. Also, keep out the cyanobacteria and algae with good water movement, and your coral will stay happy.

Availability    Porites Corals for Sale: The Jeweled Finger Coral Porites cylindrica is moderately easy to find at pet shops and on line. Online they can run about $40.00 to $60.00 USD or more depending on size and/or color.

References

Author: Carrie McBirney; Clarice Brough, CRS

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