The Stick Polyp builds its home on a worm and looks like a polyp tree, or better yet like polyps on a stick!
The Stick Polyp of the Acrozoanthus genus makes its home encrusting on abandoned tube casings of polychaete worms or fan worms. At times, they will also live on a tube casing that still has a worm residing in it. In this symbiotic relationship, the Eunice tubifex worm is still alive and secreting material to keep the tube strong, thus making a more permanent home for the Acrozoanthus. Without the worm, the tube eventually disintegrates and the Acrozoanthus will have to move onto a new home.
The Stick Polyp Acrozoanthus australiae is also known as Tree Stick Polyp, Tree Anemone, Polyp Tree, and Encrusting Stick Anemone. This is a colonial anemone that is common in the aquarium trade. It has one species in its genus, with Acrozoanthus being a recently accepted name. They have the typical polyp structure of other zoanthids, with long tentacles that do have a moderate sting. They are typically brown, gray or tan in color.
Stick Polyps can be moderate to care for, rather than easy like other zoanthids, due to their potentially brittle and breakable casing. They need high lighting, medium water flow, and regular feedings. Like sea anemones, when unhappy or if their home disintegrates, they will detach from their base and float around the tank. This becomes a problem due to the fact that they will sting whatever they come in contact with in their quest for better accommodations. Keep them at least 10″ from other sessile corals. As with most zoanthids, mushroom anemones should not be placed nearby.
Distribution / Background
Acrozoanthus Coral Information: The Acrozoanthus genus was described by Saville-Kent in 1893. There is one species in this genus and Acrozoanthus australiae is a recently accepted name. Common names this species is known for are Stick Anemones, Tree Anemones, Tree Polyp, and Encrusting Stick Anemones. The Acrozoanthus has reproduced in captivity by budding under ideal conditions.
Where Acrozoanthus Corals Are Found: The Acrozoanthus genus are found in the Indo-Pacific.
Acrozoanthus Coral Habitat: The Acrozoanthus genus inhabit coastal bays that have muddy and rocky bottoms.
What do Acrozoanthus Corals look like: Stick Polyps have soft bodies covered with a leathery skin, called the cuticle, which gives them protection. They have the typical polyp structure of other zoanthids, with long tentacles that do have a moderate sting. They are typically brown, gray or tan in color.
The Stick Polyp is a type of colonial anemone or polyp that makes its home encrusting on abandoned tube casings of polychaete worms or fan worms. At times, they will also reside on a tube casing that still has a worm living in it. If the tube casing that they are affixed to does not have a current resident, it may in time break down. This is due to the fact, that the residing worm constantly rebuilds and strengthens the tube structure with its own secretions. Life span is unknown and the colony is dependent on the lasting strength of the tube they have chosen to adhere to.
Difficulty of Care
It is thought that the Acrozoanthus may have a nutritional need derived from the tube casings of polychaete worms. This is due to their attraction to abandoned tube worm casings, yet this is still to be determined. Since the tube castings the Stick Polyp has settled on will eventually disintegrate, the individual Acrozoanthus in the wild will then float away, looking for a new home. In aquaria, they may be artificially affixed to a more permanent structure, but will need to be fed regularly.
They are a recommended aquarium coral, but with some caution. The Zoanthidae family produce palytoxin, one of the most potent poisons known to science. For this reason one should take care when handling them. Don’t handle them if you have cuts or open wounds and make sure to clean your hands after handling.
There are a couple of cautionary items to be aware of when you keep Zoanthids:
The members of the Zoanthidae family have varying degrees of poison called palytoxin. All of the Palythoa genus and most Protopalythoa genus produce a high level of this poison in their mucus and gonads. Other genera, such as the Zoanthus genus, have it to a lesser extent, and so a less dangerous degree.
To be affected by this toxin, it must either be ingested or must enter the bloodstream. It can enter the system through an open wound. It has been suggested by some that it may also be absorbed through skin contact though this is not confirmed.
The danger to the aquarist is minimal with proper precautions. If you have a cut on your hand, this poison can get into your system, but in average aquarium keeping it is unlikely to pose any danger beyond a localized skin reaction. Some hobbyists wear gloves when handling these organisms.
Here’s a couple interesting facts!
Fish that eat Paly polyps, like the filefish, can bring this palytoxin in to the human food chain. This would be when a predator of the filefish is a fish that is typically eaten by humans.
Also, Pacific tribes used to use this neuromuscular poison to paralyze enemies and prey animals by coating their spears with the mucus of these corals.
- Vibrio Infection
Vibrio can at times be in the coral mucus, thus causing a Vibrio infection in humans if care is not taken. Most people have no problem, but caution and common sense play a role here. Wearing gloves and possibly goggles may be the safe route to go. After handling a Zoanthid, make sure the mucus is not on your glove or hand before handling any other corals!
Foods / Feeding
Acrozoanthus Coral Feeding: In the wild, Acrozoanthus 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.
In captivity the Stick Polyps can be fed brine shrimp and microplankton or other similar sized foods. Feed several times a week or as needed.
Stable tank conditions are needed to keep the Acrozoanthus 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. Make sure iodine is present, and also the addition of trace elements may help with the Stick Polyps survival.
Suggested levels for Acrozoanthus 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 – 1300 ppm.
- Strontium: 8 – 10
|Quick Reference Chart
A typical live rock/reef environment is what is needed for your Stick Polyps, along with some fish for organic matter production. A mature tank (well over a year old) is advised to increase the successful keeping of Acrozoanthus.
Provide proper lighting and water movement. Moderate water flow and a strong light source are required for Stick Polyps to do well. These colonial anemones are not an aggressive species. They get along well with their own kind, but space should be provided between them and other corals.
- Minimum Tank Size / Length: 29 gallons (110 L) or larger
- Marine Lighting: High
- Temperature: 72° – 83° F (22° – 27° C)
- Salinity / Specific Gravity: 1.023 – 1.025
- Water Movement: Moderate
- Water Region: All areas of the aquarium
Compatibility and Social Behaviors
The Acrozoanthus genus will get along with itself, but does need to be placed in an area where they will not encroach on nearby corals. Like sea anemones, when unhappy or if their home disintegrates, they will detach from their base and float around the tank. This becomes a problem due to the fact that they will sting whatever they come in contact with in their quest for better accommodations. Keep them at least 10″ from other sessile corals. As with most zoanthids, mushroom anemones should not be placed nearby.
Stick Polyps are not an aggressive species. They can be kept in the company of small peaceful coral reef fish and shrimp, and hermit crabs. Other good tank mates include small tangs and blennies that will feed on filamentous algae. Avoid large crustaceans, large angelfish, and most butterflyfish. Sea Anemones and Tube Anemones should also be avoided.
Sex – Sexual differences
Breeding and Reproduction
Propagation is rather simple for Acrozoanthus corals, simply snap off a section and glue. They can be out of the water a few minutes with no ill effects. Dry rock or plug you will be putting it on then use super glue (the gel is the best) to connect them. Wait a few seconds for it to set and then put the new frag back into the water. Another method that can be used is to rubber band them to a rock or desired surface. By the time the rubber band breaks away, the zoanthid will have connected.
A snail called the Box Snail or Sundial Snail Heliacus areola preys on Zoanthid colonies, so must be removed if seen. Avoid large crustaceans and aufwachs feeders, such as large angelfish and most butterflyfish, that like to nibble on their tentacles.
Acrozoanthus Corals for Sale: The Stick Polyps or Tree Anemone Acrozoanthus australiae are very easy to find at pet shops and on line. Online they can run about $30.00 USD or more for a for a 3″ to 5″ piece.
- Animal-World References: Marine and Reef
- Eric Borneman, Aquarium Corals : Selection, Husbandry, and Natural History , TFH Publications, 2001
- Bob Goemans, Stick Polyps, Polyp Trees, Acrozoanthus australiae, Animal Library, Saltwatercorner.com