By Bob Goemans
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Euphyllia ancora

Vernon and Pichon, 1980

Hammer/Anchor Coral

Likely Reef Tank Suitable

Range: Tropical Indo and Western Pacific Ocean, and the Red Sea

Natural Environment: Inhabits shallow, often turbid reef environments receiving gentle wave action, where it forms large colonies, often with others in its genus. Usually pale brown or green with the tips of the tentacles an intense green or light brown color.

General Husbandry: This photosynthetic stony coral has very large fleshy polyps and its tentacles are tipped with a T-shaped projection similar to Thor's hammer or an anchor-like projection, thus the name Anchor or Hammer Coral. Its long fleshy polyps are fully extended during daytime and partially retracted during nighttime, at which time very long sweeper tentacles are displayed in an effort to clear a path for expansion of the colony. So leave sufficient space downstream from it. However, it can co-mingle without any tissue damage with E. divisa.

Even though its photosynthetic and a suspension feeder in the wild, it can be hand fed if desired. Occasional feeding, such as once per week with meaty foodstuffs such as fortified brine shrimp, mysis, rotifers, and/or products containing Cyclop-eeze or similar foodstuffs appear quite beneficial, yet not necessary for its continued wellbeing.

This coral is quite common in the trade, yet it’s not always easy to maintain as it’s often either environmentally placed poorly in some aquaria or damaged specimens have been purchased. One should remember that most specimens found in stores are pieces broken off the original colony. This collection method often tears its flesh, opening the new specimen to infection. Shipping stress also adds to the health problem, and it often becomes difficult to find healthy specimens. But if a healthy specimen is found, it makes for a good addition to most reef aquaria.

For those specimens that develop RTN, I treat with a diluted solution of Lugols iodine. I begin by first preparing a 'liter’ of aquarium water containing 8 drops of Lugols iodine and mixing well. If feasible, I also prepare a small holding container (hospital tank), such as a glass fish bowl or small aquarium, just large enough to house the cleaned specimen. It is filled with aquarium water that has 4 drops of Lugols iodine added to it per 'gallon.’ It has no substrate, but does contain a small powerhead for circulation and is moderately lit. When fully prepared, I remove the infected specimen and over an empty pail, used a soft brush and the prepared liter solution to remove as much brown jelly as possible. Then use a turkey baster filled with the remaining 8-drop solution and squirt only those brushed areas while continuing to hold the specimen over the empty pail. The specimen is then placed in the hospital tank, which should have the same pH, specific gravity, and temperature of the aquarium. It remains there, with 10% water changes (using water from the show aquarium with no additional Lugols) every other day until I’m sure the brown jelly infestation has ceased. If necessary, I’ll repeat the cleaning process. I’ve found the sanitizing effect of the Lugols to often quickly end the invasion of brown jelly.

There’s also reports that in aquariums’ containing Sinularia leather corals, Euphyllia spp. do not always fair well, possibly because of the chemicals released by some Sinularia species. Nevertheless, those in my past aquariums with various Sinularia species have not experienced a similar fate. But its worth mentioning nevertheless.


There are two species groups in this genus. One forming "phaceloid" colonies, containing the species E. glabrescens, E. paradivisa, E. paraancora, and E. paraglabrescens. The second group (originally described as E. fimbriata), forming "flabellomeandroid" colonies, appears to include E. divisa, E. ancora and possibly E. yaeyamaensis, if that remains as a valid species.

Keep in mind that not only can its sweeper tentacles injure other corals, it can leave the aquarist with a painful rash-like condition. Handle with care, and if possible use a glove-covered hand when handling this coral.

And always select a specimen that does not have any kind of alga growth on any of its exposed skeleton surface, as it will cause the tissue to recede, usually leading to the animals demise sooner or later. And do not remove a specimen with highly inflated tissue areas from the water as the weight of the water in the polyps may damage or tear its flesh lose from its skeleton material. Gently shake the specimen and allow the flesh to retract somewhat before removing.

Has a temperature range of 74 to 83°F (23 - 28°C).

 Euphyllia ancora (Hammer/Anchor Coral)
Photo © Bob Goemans
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