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Pacific Encrusting Gorgonian
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Pacific Encrusting Gorgonian

Star Polyp

Pacific Encrusting Gorgonian Briareum stechei, also known as Star PolypsBriareum stecheiPhoto © Animal-World: Courtesy David Brough

   The Pacific Encrusting Gorgonian is one of the most adaptable corals, easy to care for and easy to propagate!

   The Pacific Encrusting Gorgonian Briareum stechei is a very hardy and durable gorgonian. The Briareum species are found in both the Pacific and Atlantic Oceans. They are very common in nature, found in waters that are just a few inches deep to depths of 100 feet (30 m). The Briareum corals primarily form an unbranched, encrusting coral with a low profile stolon, or mat. Some species also have an erect growth and will sparsely form thick, short upright stalks or lobes from the mat.

   The mat of the Briareum corals can be smooth, or on some specimens can have bulbous or slightly raised calyces (bumps) where the polyps reside. The tissue of the mat is a gray, tan, or a shade of purple. The polyps have long feathery or grass-like tentacles. The tentacles of the Pacific species are usually green while they are brown in the Atlantic species. The tentacles are generally extended, but they can fully retract into the mat if disturbed. They are very robust and will eagerly encrust other living corals, especially other gorgonians.

   The Pacific Encrusting Gorgonian B. stechei resembles the True Star Polyps of the Pachyclavularia genera, with a well known example being the Green Star Polyps Pachyclavularia (Briareum) violacea. Some experts treat these two genera as synonymous though the Pachyclavularia genera appears to have important identifying 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.

   The Briareum species from the Atlantic are commonly known as Deadman's Finger, Corky Sea Finger, or Moss Coral. These can resemble, though are not closely related too, species from the Erythropodium genera, like the Encrusting Gorgonian E. caribaeorum. Some distinctions are that the polyps of the Briareum corals can reside in raised calyces or bumps on the surface rather than having a smooth surface like the Erythropodium. They can also form short upright extensions arising from the mat which are mostly absent from the Erythropodium species.

   The Briareum genus is very easy to care for and the only requirement is moderate to strong turbulent water flow. Most light is acceptable, although they grow faster with higher light levels. 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. But please be careful when handling since they are one of the most noxious of the gorgonians known to scientists.

To learn more about these fascinating Octocorals see:
What Are Gorgonians?
Types of Gorgonians, Sea Fans and Sea Whips


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Scientific name    Suborder: Scleraxonia
   Family: Briareidae
   Species: Briareum stechei

Distribution / Background    Gorgonian Information: The Briareum genus was described by de Blainville in 1930. There are about 8 species and they are B. asbestinum, B. contortum, B. excavata, B. gorgonoideum, B. grandiflorum, B. hamrum, B. palmachristi, and B. stechei. The Pacific Encrusting Gorgonian B. stechei was described by Kükenthal in 1908.

   The Briareum genus has been propagated in captivity. Some common names the Atlantic species are known for are Corky Sea Finger, Deadman's Finger, Moss Coral, and Encrusting Gorgonian. Common names Pacific species are known for are Pacific Encrusting Gorgonian and Star Polyps. The most well known species is the Corky Sea Finger B. asbestinum which will encrust and grow protrusions.

   True Star Polyps are of the Pachyclavularia genus. They have a bright purple to reddish colored mat and very green, yellow, or light green tentacles.

   Where Briareum Corals Are Found: The Briareum genus are found in both the Atlantic and Pacific Oceans. In the Western Atlantic they are found along the US and Canadian coasts as well as in the Caribbean.

   Briareum Coral Habitat: The Briareum genus are very common and found on all reef areas. The waters vary, having strong or weak water movement. The waters can also be very clean or very nutrient rich, and they can have varying amounts of lighting. These corals inhabit depths from 3 to 131 feet (1 - 40) with some species, like the Pacific Encrusting Gorgonian B. stechei, even found in just ankle deep water.

Status    The Briareum genus is not on the IUCN Red List for Endangered Species.

Description    What do Briareum Corals look like: The Briareum genus are encrusting gorgonians. They form mats that are purplish gray or tan with slightly raised calyces that are more of a nub than a tube. Out of those projections are long grass-like polyps that are brown, pink, or green. The tentacles of the Pacific species are usually green, while they are brown in the Atlantic species.

   The polyps are always expanded unless an outside stimuli disturbs them, then they can retract fully. They generally cover over other corals, but prefer to take over gorgonians. Other gorgonian species will encrust over whatever is available. They can grow 2 to 4 inches per year (4 - 10 cm) and can grow up to 3 feet in height (1 m).

   Sometimes the Briareum genus can be confused with other encrusting and mat polyp corals. The Pacific Encrusting Gorgonian B. stechei resembles the True Star Polyps of the Pachyclavularia genera. Some experts treat these two genera as synonymous and the Pachyclavularia genera may eventually be reclassified as Briareum. For now however, the Pachyclavularia is generally distinguished by a brighter 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 True Star Polyps in the Pachyclavularia genus, they can also form upright finger like protrusions from their base and shed mucus "sheets".

   The Briareum species from the Atlantic can resemble (though are not closely related too) species from the Erythropodium genera. Some distinctions are that the polyps of the Briareum corals can reside in raised calyces or bumps on the surface while the Erythropodium species have a smooth surface. They can also form short upright extensions arising from the mat which are mostly absent from the Erythropodium species.

   Classification of gorgonians in general is done by some simple visual clues such as colony size, shape, axis structure, color, polyp placement, and pattern of branches. Getting a little more technical, they also look to see if the polyp is autozooid or siphonozooid. Then there is the more exacting use of chemotaxonomy. This is being used to show the different terpenoids or other chemicals produced by each gorgonian species

Difficulty of Care    Gorgonian Care: The Pacific Encrusting Gorgonian B. stechei is very easy to care for and the only requirement is moderate to strong turbulent water flow. Most light is acceptable, although they grow faster with higher light levels. 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. Please be careful when handling since they are one of the most noxious of the gorgonians known to scientists.

Foods / Feeding    Gorgonian Feeding: In the wild, Briareum corals have developed several feeding strategies. They capture microscopic food particles from the water column and can absorb dissolved organic matter. Unlike a lot of other gorgonians corals, the Pacific Encrusting Gorgonian B. stechei has a symbiotic relationship with a marine algae known as zooxanthellae, where they also receive some of their nutrients.

   In captivity, the Pacific Encrusting Gorgonian will use light and their zooxanthellae for a food source, and will also use a mucus net to capture particulate matter. Feed live enriched artemia nauplii and other similar sized foods.

Aquarium Care    Stable tank conditions are needed to keep the Briareum 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. Iodine, calcium, strontium, and other trace elements can be added to maintain proper levels for good growth. The Briareum genus is also one of the most noxious of the gorgonians, with the Corky Sea Fingers B. asbestium being one of the most toxic species known to scientists at this point. So using media that helps to absorb toxins is suggested.

   Suggested levels for Briareum 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

Aquarium Parameters

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

   A typical live rock/reef environment is what is needed for your Pacific Encrusting Gorgonian, along with some fish for organic matter production. The B. stechei 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 highly adaptable to any lighting but will do well with better lighting, and a good water flow is essential. They produce a mucus sheet which they use for feeding. Every 10 days or so, they may slough off this mucus sheet to keep bacteria and sediment from collecting. If they are in more turbid water they will do this less often.

  • Minimum Tank Size / Length: 50 gallon (190 L) or larger
  • Marine Lighting: Moderate to high
  • Temperature: 72° - 78° F (20° - 26° C)
  • Salinity / Specific Gravity: 1.023 - 1.025
  • Water Movement: Moderate and turbid
  • Water Region: Bottom of the aquarium

Compatibility and Social Behaviors    The Pacific Encrusting Gorgonian is very aggressive in that it will encrust other corals, but prefers to take over gorgonians. This genus needs to be contained, or it will over grow nearby corals. They can be put on a rock with sand around it with at least 4" or more of space between them and the main rock work.

Sex - Sexual differences    No sexual difference in appearance is known.

Breeding and Reproduction   The Briareum genus will form daughter polyps from the edge of their mat as well as release gametes into the water. Some species will form planulae with their young brooding on the surface of the colony.

  Propagation is easy, simply cut off pieces of a branch or mat and glue them (use cyanoacrylate glue), 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.

Potential Problems   The Briareum genus is hardy and very easy to care for. However they are susceptible to detritus collecting, and algae growing in-between their stalks if the water is not at least moderate and turbulent.

Availability    Gorgonians for Sale: The Pacific Encrusting Gorgonian B. stechei is easy to find at pet shops and on line. Online they can run about $12.00 USD or more, depending on size.

References

Author: Clarice Brough CRS

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