Pulsing Xenia, Red Sea XeniaXenia Sp.Photo © Animal-World: Courtesy Greg Rothschild
Pom Pom Coral, Bouquet Encrusting Coral
The Pulse Coral, with its pumping action and bouquet shape, is one of the most beautiful flower corals!
The Pulse Corals Xenia sp. are some of the most endearing corals, and are highly favored by reef enthusiasts. With their pulsing heads and the gentle waving of their polyps in the water, they produce an almost mesmerizing affect to the viewer. Since they tend to grow in the direction of the water flow that they are near, you can get them to grow where you want in the reef tank. Getting them to grow up the back wall of the aquarium makes for an interesting display.
Most species from the Xenia genus have unbranched stalks that are short, thick and smooth, from which the polyps arise. They can be cream, white brown, ivory and light green. The color is uniform with just a little contrast between the stalks and polyps. The polyps can contract considerably but do not retract inside the coral. Not all Xenia pulsate, but the species that do will generally pulse about 8 times per minute, yet there can be quite a variation in the strength and speed of the pulsing action.
There is no proven reason why Xenia corals pulse. Many experts and aquarists attribute a variety of reasons for the pulsing phenomena. One thought is that they are pulsating to help with respiration and gas exchange. Water chemistry also plays a role in their pulsing, along with lighting and current, just what combination is hard to tell. They are sensitive to falling or low pH and will stop pulsing when the pH is below 8.3. Adding small amounts of carbon will take some organics out of the water. Some aquarists have found this to induce the polyps to pulse, as if the coral is trying to try pull more nutrients from the water. Supplements of iodine are also suggested by some, but with caution as Lugol's has been found to be detrimental to some Xenia colonies. If your Pulse Coral is pulsing, then keep doing what your doing!
The Xenia corals are not the only pulsing corals. The Xeniidae family itself is considered unique in the coral world because of this ability. From this family, at least five other genera will pulse. Some of those common to aquarists include the Pom Pom Zenias of the Heteroxenia genus and the Waving Hand Coral or Glove Coral Anthelia sp.. Anthelia corals form an encrusting mat and their cylindrical polyps grow directly from that base. Xenia are different from Anthelia since Xenia polyps rise from a capitulum (top of the stalk) forming small colonies that are only a few inches tall (up to 4").
The Pulse Coral Xenia sp. can be easy to care for, depending on proper handling procedures. If you need to handle them, do so very briefly and with gloved fingers. When handled they stress and produce lots of mucous, which in turn attracts bacteria, leading to death. This is also the reason they do not travel well. This production of mucous attracts bacteria, and being trapped in the shipping bag causes the bacteria to consume the Xenia. Though their primary difficulty is in shipping, once established in the aquarium they can be very hardy and are one of the fastest corals to multiply.
To learn about different types of soft corals, see:
Soft Coral Facts
Distribution / Background Soft Coral Information: The Xenia genus was described by Lamarck in 1816. There are over 60 species, and a few are X. elongata, X. macrospiculata, X. mucosa, X. multipinnata, X. stellifera, and X. umbellata. Some common names these corals are know for are Pulse Coral, Red Sea Xenia, Pulsing Xenia, Encrusting Coral, Pom Pom Coral, and Bouquet Encrusting Coral.
The Xenia genus has been propagated in captivity, and acquiring these types of specimens is a good idea, since they are hardier than their wild counterparts. Some aquacultured names are White Pom Pom Xenia, Silver Branch Pumping Xenia, and Blue Xenia.
Where Xenia Corals Are Found: The Xenia genus are found in the Indo-Pacific and the Red Sea.
Xenia Coral Habitat: The Xenia genus tend to grow on vertical surfaces in the wild. They are found at depths of 0 to 30 feet (0-9 m) in bright light, and are exposed to tidal conditions.
Xeniids have been found growing in water polluted by pipes of hotels and resorts. They are almost like an aquatic weed. They are the first to form colonies on a reef area and can "walk" with attachment and detachment of their stalks and branches. In the wake of their "walk" they will encrust over other living corals and plants.
Description What do Xenia Corals look like: Most species from the Xenia genus have unbranched stalks that are short, thick and smooth, from which the polyps arise. These stalks can have small oval sclerites, depending on the species. Sclerites are small calcareous bodies that can help support soft corals. The polyps do not retract inside the coral, but can contract considerably. They can be cream, white brown, ivory and light green and the color is uniform with just a little contrast between the stalks and polyps.
The stalk has a grouping of feathery polyps at the end, with each polyp having a 1" to 2" long stem.Their tentacles are pinnate, or feathering to different degrees, depending on the species. Deep water species have thinner tentacles and pinnules, and shallower species are thicker with more robust attributes. For example, X. elongata have sturdy stalks that are tall and grow up to 3" long. Xenia are different from Anthelia since Xenia polyps rise from a capitulum (top of the stalk) and form small colonies that are only a few inches tall (up to 4").
Not all Xenia pulsate, but the species that do will generally pulse about 8 times per minute, yet there can be quite a variation in the strength and speed of the pulsing action. Xenia can live from 1 to 7 years, with 3-7 being most common in captivity.
Difficulty of Care Soft Coral Care:The Pulse Coral Xenia sp. can be easy to care for, depending on proper handling procedures. If you need to handle them, do so very briefly and with gloved fingers. When handled they stress and produce lots of mucous, which in turn attracts bacteria, leading to death. Though their primary care difficulty is in shipping, once established in the aquarium they are can be very hardy and are one of the fastest corals to multiply.
Foods / Feeding Soft Coral Feeding: In the wild, Xenia corals have developed several feeding strategies. They can absorb dissolved organic matter, some species capture microscopic food particles from the water column, and they have a symbiotic relationship with a marine algae known as zooxanthellae, where they also receive some of their nutrients.
In captivity target feeding is pretty much pointless, and stocking enough fish as a source of dissolved organics is all you need. Tanks without fish need a mature sand that can be stirred to get the organics in the the water column. Some have stated micro zooplankton may be added if desired.
Aquarium Care Stable tank conditions are needed to keep the Xenia 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. Soft corals still need to have proper chemical levels for proper growth. Adding trace elements helps to keep those nutrients in the water which benefit them. Maintain pH at least at 8.3.
Some have indicated the use of iodine, yet use sparingly and do not exceed manufacturers suggested doses. It is suggested to only use 1/2 the dosage amount as you start off with your new colony, and then increase it slowly over time as the colony becomes established. One way you can gauge the amount is by watching the development of brown algae, diatoms. Established, well maintained aquariums only need the glass scraped free of brown algae about once a week or even longer. Too much iodine is indicated by excessive algae growth.
Suggested levels for Xenia 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 Pulse Coral, along with some fish for organic matter production. Attach the Pulse Coral to a hard substrate once introduced to the tank.
Provide proper lighting and water movement. The Xenia corals like a moderate to high, and turbid water flow. They grow fast under Metal Halides and high intensity T5 bulbs and similar bulbs. If the tank is shallower than 18", even standard output fluorescent lighting can be used. If the levels are not high enough in the lighting scheme you have, or you need new bulbs, some Xeniids will change color or increase in size. This deepening color change is from the coral actually cultivating more zooxanthellae to catch the lowered light levels. The Xenia genus is non- aggressive toward other nearby corals.
- Minimum Tank Size / Length: 10 gallon (38 L) or larger
- Marine Lighting: Moderate to high
If your Xeniid is starved for light, it will expand and extend its stalks to try and get more light. This can give the aquarist the illusion of health, when in fact this is a good indication that your lighting is deficient.
- Temperature: 68° - 83° F (20° - 28° C)
- Salinity / Specific Gravity: 1.023 - 1.025
- Water Movement: Moderate to strong, turbid
- Water Region: Middle to top of the aquarium
Compatibility and Social Behaviors The Xenia genus is non-aggressive as far as stinging or affecting nearby corals. They do not do as well in tanks with low nutrient levels, such as for Small Polyp Stony Corals SPS and other corals that need a more pristine environment, yet they will not harm these corals chemically. The Sarcophyton Leather Corals seem to help Xeniids flourish, though this is not entirely understood.
Xenia corals can move, and will actually "climb" up to areas where there is more light if they need to. Make sure no corals are around that can be "grown" over.
Breeding and Reproduction The Xenia genus reach sexual maturity within one year, and have several methods of reproduction. They will reproduce naturally in captivity by longitudinal fission, notably several times a month once the colony is mature. They will also use budding as another way of reproducing, or pinnitomy (pinnules falling from the polyps and attaching to the substrate to start new colonies). Some aquarists have actually snipped off individual polyps from the cap of dying colonies, and found that they will settle elsewhere in the aquarium and start new colonies. Some species will expel brooded planulae (free-swimming larvae) in some captive environments. Xenia can also 'walk' to split a colony, leaving a trail of tissue that will start into a new colony.
To propagate Xenia in captivity, be sure to use gloves and be aware that your Pulse Coral will stink once you pull it from the water. Stalked Xenia should be cut longitudinally between the branches and affixed to a solid surface with a rubber band or reef glue. Because they are so fast growing, some reef farmers allow the Xenia to grow over netting. They then cut those into small frags and use reef glue to affix them to plugs or rock. The product, SeaChem's Reef Plus, has been suggested to add to the tank at 3 to 6 times the recommended dosage to help with healing frags.
Potential Problems The Xenia genus is susceptible to a periodic die off that seems to coincide with lunar events. Clipping the tips of a dying colony and letting them settle on their own may help preserve some colonies. Also watch out for a little nasty crab that assumes the color of the Xenia. The tiny Xenia Crab is usually found in pairs at night, on top of the closed heads, and it slowly eats the Pulse Coral away. Polychaete worms can also chew at your Xenia.
The Xenia genus is susceptible to stress from shipping and they do not travel well. When stressed they produce lots of mucous. This production of mucous attracts bacteria, and being trapped in the shipping bag causes the bacteria to consume the Xenia. It has been stated that Xenia can be shipped dry for short distances (less than 12 hours on average and not in extreme weather) since this will help with keeping the bacteria level down from the mucous they produce. They will produce a mucous layer to protect themselves from the air (just like in the wild during low tide), but the benefit is that they do not suffer from fouled shipping water.
Some hints for dry shipping, and acclimating a dry shipped Xeniid:
- Moisten the inside of the container and put a little bit of water at the bottom, yet away from the Xenia. (In extreme temperatures, very hot or very cold, submerging them in water would be better, rather than dry shipping.)
- Suspend the coral in the shipping container to prevent it from hitting the sides of the package, and prevent it from coming in contact with the small amount of water at the bottom. Suspend the Xenia upside down by fastening it to styrofoam or other buoyant material.
- Maintain the proper and constant temperature of the coral's packaging.
- When acclimating them, match the water parameters of your tank to those from where they were shipped.
- They will shed the mucous they accumulated when placed in the new tank (just as if the tide had come back), so must be exposed to strong water movement to help them recover.
- 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
- Ronald L. Shimek, Guide to Marine Invertebrates: 500+ Essential-to-Know Aquarium Species, Microcosm, 2005
- Harry Erhardt and Horst Moosleitner, Marine Atlas Volume 2, Invertebrates (Baensch Marine Atlas), Mergus Verlag GmbH, Revised edition, 2005
- Bob Goemans, Pulse Corals, Animal Library, Saltwatercorner.com
- The Frugal Reefer, You can mass produce Xenia for trade or sale, Garf. org, referenced 2010
- Pulsating Xenia, Reef Corner, referenced 2010