The Pearl Bubble Coral is a hungry little dude, thriving best when kept well fed!
The Pearl Bubble Coral Physogyra lichtensteini is also known by such names as the Octobubble Coral, Pointed Bladder Coral, Grape Coral, Pearl Coral, Small Bubble Coral, Octopus Coral, and even the Tipped Bubblegum Coral. In the wild they grow in a meandroid fashion, where the polyps form valleys and hills. Though the P. lichtensteini was once quite rare in the aquarium trade, it is commonly available today.
The Pearl Bubble Coral is quite similar to the ‘grape’ corals or ‘bladder’ corals of the Plerogyra genus. Like the Bubble CoralPlerogyra sinuosa and the Pearl Coral Plerogyra flexuosa, the Pearl Bubble Coral has water filled vesicles (bubbles) that will actually inflate or deflate, depending on the light available. The bubbles differ in size however, with the vesicles of the Pearl Bubble Coral reaching only about 3 – 5 mm in diameter, while the Plerogyra spp. reach about 1/2″ to 1″ (1 – 2.5 cm).
The color of the P. lichtensteini can be pale gray, to a dull or bright green. During the day, its surface is covered with masses of small oval grape like bubble clusters that will retract when touched. These little bubbles will deflate when the sweeper tentacles come out at night, exposing it skeletal structure. Be cautious, while the bubbles do not have toxins, these feeding tentacles are capable of delivering a sting.
The Physogyra genus can be easy to moderate to care for as long as you don’t blast them with sudden or high currents and high intensity lighting. The Pearl Bubble Coral is quite content with low lighting, gentle currents, and being careful to not damage their tissue. They enjoy, but do not require, bright light. If you expose a green or light colored Pearl Bubble Coral to high light levels, expect it to turn brown to compensate for the intensity. This it will not harm the coral, but to be kept under stronger lighting, they will need to be acclimated over a period of time. These guys, like their fellow “bubble corals” are hungry and need to be fed daily for best results.
Pearl Bubble Coral, Physogyra lichtensteini greenish
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Showing short feeder tentacles
This video gives an idea of what your Pearl Bubble Coral will look like during the day. The small water filled “pearl” sized bubbles are actually modified tentacles! Thats right! They are designed to protect the polyp below and these bubbles can range from tan to green or gray to white. The feeder tentacles are a few inches. The tips of the bubbles have “nipples” and several clownfish love to host this guy! Growing to almost 10 feet, space needs to be kept in mind!
Pearl Bubble Coral, Physogyra lichtensteini bright green
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This video shows what the Pearl Bubble coral looks like when feeding. The video starts out before lights out, progresses to lights out and feeding then the aquarist turns the lights on to get a good look at this new appearance when feeding. You can see the bubbles are quite deflated and the feeder tentacles are out. No sweepers in this video.
Pearl Bubble Coral, Physogyra lichtensteini night time
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How this coral looks at night
What happened? Nighttime! This coral takes on an almost alien appearance at night! You can see the blade like septa or skeletal “teeth” through the pale clearish polyps with the retracted tentacles. The feeder tentacles are out and are a few inches long and are white. This coral should be fed daily.
Pearl Bubble Coral, Physogyra lichtensteini sweepers
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Video showing the reach of the coral
Reaching 3 to 4 times as long as the short feeder tentacles, these sweeper tentacles come out at night. Their job? To sting and ward off potential encroachers on their space! The personal space of your Pearl Bubble Coral, well in the wild at least, can be up to 10 feet! That’s right, these bad boys can grow to 10 feet, not including the up to 8″ reach of the sweepers! Very cool and very scary at the same time!
The family Euphyllidae, “… is a very large family of zooxanthellate scleractinans, that were previously grouped in the family Caryophylliidae (Mather, 1994). It includes such genera as Euphyllia, Catalyphyllia, Nemenzophyllia, Plerogyra, and Physogyra.” Source: Tropical Marine Biology II, Classification of Scleractinian (Stony) Corals, by Pierre Madl, University of Vienna, 2001, Revised in Nov. 2002
Distribution / Background
Physogyra Coral Information: The Physogyra genus was described by Milne-Edwards and Haime in 1851. There are 5 nominal and 3 true species in this genus, with the most familiar species being the Pearl Bubble Coral P. lichtensteini and P. exerta. Some common names these corals are know for are Octobubble Coral, Pointed Bladder Coral, Bubble Coral, Grape Coral, Pearl Bubble Coral, Green Bubble Coral, Octopus Coral, and Tipped Bubblegum Coral. The Physogyra genus has been reproduced in captivity.
Where Physogyra Corals Are Found: The Physogyra genus are found in the Red Sea, then south along Africa’s east coast, ending 1/2 way down the continent, then eastward around Madagascar and the Mauritius Islands. They continue east to the top of Australia’s northern coast, including the Great Barrier Reef, Coral Sea and Ningaloo Reef. From there, they continue east and are found from New Caledonia to Samoa. From Samoa, their habitat curves back north west to the Marshall Islands, Guam, and the Ryukyu Islands. Continuing back westward, they are found around Taiwan, Vietnam, the Philippines, Indonesia, and then back to Maldives, where they finally make a full circuit back to where we started, the Red Sea.
Physogyra Coral Habitat: The Physogyra genus are found in depths up to 131 feet (40 m) in turbid water with tidal currents. They inhabit lower reef slopes, caves or crevices, and under overhangs. They prefer protected habitats like crevices and overhangs in shaded or deeper areas of the reef. They can be found in low light areas that have almost total shade or in shallower brighter waters, yet all habitats have turbid waters.
What do Physogyra Corals look like: The Physogyra genus grow in a meandroid fashion, where the polyps form valleys and hills. There are pieces of sharp, delicate, thin “bone” called septa in-between the bubbles, so care needs to be taken to prevent the bubbles from getting “popped” on this skeleton. Their septa are large, smooth and spaced well apart and they grow in a horizontal orientation.
During the day, the surface of the Physogyra spp. is covered with small grape like bubble clusters that will retract when touched. These oval water filled vesicles (bubbles) are not polyps, but modified tentacles which protect the delicate polyps beneath them. The bubbles will expand or contract as needed for acquiring more or less light during the day, but at night they deflate. Then 3 – 4″ (7.5 to 10 cm) feeder tentacles, which CAN sting, emerge looking for food. There are also small short tentacles sometimes seen with the bubbles during the day, and these also do not sting.
The Pearl bubble Coral colors can be pale gray to dull or bright green, but will turn brown if the light is too high. It looks like a small version of the Plerogyra corals, which have the very large round bubbled surface. The surface of P. lichtensteini is covered by more numerous little “bubbles,” which are about 3 – 5 mm in diameter. The “octobubble” term comes from the bubbles on the Pearl Bubble Coral, or Octobubble Coral, being “nippled” at the tip.
The Physogyra genus colony can grow to 12″ (30 cm) in diameter, but most imported specimens are smaller. Their lifespan is unknown.
Difficulty of Care
Physogyra Coral Care: The Physogyra genus can be easy to moderate to care for as long as you don’t blast them with sudden or high currents and high intensity lighting. The Pearl Bubble Coral is quite content with low lighting, gentle currents, and being careful to not damage their tissue. Tickle the tissue to help it recede before lifting it out of the water. This will help prevent the tissue from tearing from its own weight against their sharp skeletal structure.
If you expose a green or light colored Pearl Bubble Coral to high light levels, expect it to turn brown to compensate for the intensity. This it will not harm the coral, but to be kept under stronger lighting, they will need to be acclimated over a period of time. These guys, like their fellow “bubble corals” are hungry and need to be fed daily for best results
When choosing your new charge, make sure the LFS employee gently shakes the coral until most of the bubbles deflate and recede. Removing it to air while inflated will cause tears in the flesh, leading to infection. Even if the coral is left submerged, the septa can cut into the bubbles against the bag it is being put into. Also, make sure there is no algae on the septa once it is visible. If you do see some, you will have to clean it off if you purchase the coral.
Foods / Feeding
Physogyra Coral Feeding: The Physogyra corals are considered planktivores and have developed several feeding strategies. Through a symbiotic relationship with a marine algae, known as zooxanthellae, they receive many of their nutrients. They also capture planktonic organisms, food particles from the water column, and can absorb dissolved organic matter.
In captivity, they can be fed when the feeder tentacles are out in the evening with mysis, rotifers, enriched brine shrimp, Cyclopeeze and other similar sized meaty foods. Also you can shred whole fish or shrimp and feed the entire organism to the coral. Since different parts of the animal have varying nutritional qualities, this practice of feeding your Physogyra in such a way will yield good results. These corals are hungry all the time, so feeding as needed with various foods is helpful. That may also help keep them from sweeping their tentacles too far.
Typical water changes of 20% a month, 10% biweekly, or 5% weekly are needed. It has been noted that 5% weekly water changes replenish many of the needed additives and it is ultimately cheaper than purchasing additives for the water. With higher concentrations of coral with calcareous skeletons though, there may be a need put in additional additives to maintain proper levels for good growth.
The following water supplements are suggested for Physogyra species:
- Calcium: 400 to 450 ppm. If a large poly stony (LPS) coral does not have enough calcium, it will not grow. (Seachem makes a calcium additive that states 385 as sufficient)
- 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: 1200 – 1350. Magnesium makes calcium available, so if your calcium is low, check your magnesium levels before adding any more calcium.
- Strontium: 8 – 10
A well-feed live rock/reef environment is what is needed for your Octobubble Coral, along with some fish for organic matter production. A mature tank is recommended. Provide gentle water movement and low to moderate light. They can actually increase and decrease their bubble size if they need more light. If you expose a green or light colored Pearl Bubble Coral to high light levels, expect it to turn brown to compensate for the intensity. This it will not harm the coral, but to be kept under stronger lighting, they will need to be acclimated over a period of time.
|Quick Reference Chart
They are fairly hardy but are more easily injured than other LPS coral species like the Elegance coral. There are usually pieces of sharp, delicate, thin “bone” called septa in-between the bubbles, so care needs to be taken to prevent the bubbles from getting “popped” on this skeleton. Feed them regularly and be careful to not damage their tissue. Make sure that no other corals can come in contact with your Physogyra as they are aggressive and will sting other corals.
- Minimum Tank Size / Length: 50 gallons (190 L) or larger
- Marine Lighting: Low to moderate light
- Temperature: 74° – 83° F (23° – 28° C)
- Salinity / Specific Gravity: 1.023 – 1.025
- Water Movement: Low / turbulent.
- Water Region: Bottom to mid areas of the aquarium, depending on lighting
Compatibility and Social Behaviors
The Physogyra genus is aggressive, and their sweeper tentacles can punch a powerful sting to other corals as well as humans. They should tolerate their own species, but should be positioned away from all other corals. Despite their aggression, they have been known to die in the presence of a large leather coral population (Sinularia), since the leathers do emit a toxin that will harm the Physogyra. Hermit crabs also tend to pester them to the point of stress and death.
Sex – Sexual differences
Breeding and Reproduction
The large polyp stony (LPS) corals are male and female and can reproduce both sexually and asexually. In the wild they reproduce sexually by releasing eggs and sperm at the same time, resulting in a fertilized egg which then forms into a free-swimming planula larva. Eventually the planula larvae settles onto the substrate, becoming plankters. This then forms a tiny polyp which begins to excrete calcium carbonate and develops into a coral. Planula larvae are extremely vulnerable to predation, and very few survive. Physogyras reproduce asexually as well.
The Physogyra genus will release gametes for external fertilization from the male and female colonies. They are also known to bud when well fed and happy. Propagation needs to be left up to the coral. Cutting into the tissue will result in damage that can lead to disease. It is best to feed them well and keep them happy, then they will form buds which can be harvested and produce quite a few colonies a year! Just be patient. The larger your coral gets, the more “babies” it will give you.
- Brown Jelly
Brown jelly or protozoan infections can infect the rest of the colony if not treated. This brown jelly looks exactly like it sounds, and can be caused by poor water quality and/or tissue damage. To treat, remove the coral to a container with water from the main display, then brush or siphon off any visible brown jelly. Give the coral a freshwater dip in water with the same pH and temperature as the main tank for several minutes to kill a lot of the microorganisms.
Use an antibiotic paste on the infect areas and/or a Lugol’s dip. Cyanobacteria and brown jelly infections can be treated with Neomycin sulphite, Kanamycin and other broad-spectrum antibiotics. The pill can be pulverized into a fine powder, mixed with sea water to make a paste, and then applied to the wound, or affected site of the coral with a simple artists brush.
Try to treat the coral with the least stressful method first. Place in a quarantine tank until coral recovers.
They are also susceptible to algae growing on exposed skeleton, so make sure the water flow is adequate and your phosphates are zero. If micro-algae seems to be getting the best of your coral on its exposed skeleton, use a soft brush to scrub off the algae. An electric rotary tool can be used on particularly stubborn algae.
Physogyra Corals for Sale: The Pearl Bubble Coral or Octobubble Coral P. lichtensteini is very easy to find at pet shops and on line. Online they can run about $35.00 to $70.00 USD or more depending on size and/or color.
- Animal-World References: Marine and Reef
- Harry Erhardt and Horst Moosleitner, Marine Atlas Volume 2, Invertebrates (Baensch Marine Atlas), Mergus Verlag GmbH, Revised edition, 2005
- 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
- J.E.N. Veron, Corals of Australia and the Indo-Pacific , University of Hawaii Press; 2 Rev Ed edition, 1993
- Ronald L. Shimek, Guide to Marine Invertebrates: 500+ Essential-to-Know Aquarium Species, Microcosm, 2005
- Bob Goemans, Octopus / Pearl / Grape Coral, Physogyra lichtensteini, Animal Library, Saltwatercorner.com