There’s quite a number of LPS corals in the reef keeping hobby but today’s topic of interest is the Hammer coral (Euphyllia Ancora and Euphyllia Paraancora). This large polyp stony coral is well-known for a lot of reasons.
Hammer corals are very attractive and fast-growing, capable of attaining large sizes, hardy and able to thrive in aquariums with moderate flow and lighting conditions.
Keep reading for everything there is to know about the Hammer coral, including how to care for them in reef tanks, fragging, and potential problems you may encounter.
Quick Notes about Hammer Corals
| Name | Hammer coral |
| Common Names | Anchor coral, Sausage coral, Ridge coral, Bubble honeycomb coral |
| Scientific Name | Euphyllia Ancora and Euphyllia Paraancora |
| Tank size (minimum) | 20 gallons (~80 liters) |
| Keeping | Easy |
| Propagation | Easy to moderate |
| Lighting |
Moderate |
| Water flow | Low to Moderate |
| Optimal Temperature | 24 – 28°C (~76°F – 83°F) |
| Optimal Salinity | SG = 1.023 – 1.025 |
| Optimal PH | 8.1 – 8.4 |
| Optimal KH | 8 – 12 |
| Nitrate | Less than 20 ppm |
| Feeding | Photosynthetic |
| Tank placement | Bottom to Middle |
| Growth Rate | Slow to moderate |
| Toxicity |
Yes |
| Invasive | No |
| Temper | Semi-aggressive |
| Color Form | Brown, blue-grey, green, purple, orange, yellow or gold |
Origin of Hammer Corals
The renowned Euphyllia Ancora and Euphyllia Paraancora, better known as Hammer coral is a relative of the Frogspawn and Torch corals which are all native to the Indo Pacific reef regions.
This LPS coral was described by John Veron and Michel Pichon in 1980 and here’s its taxonomical hierarchy:
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Scleractinia
Family: Euphylliidae
Genus: Euphyllia
Species: Euphyllia Ancora and Euphyllia Paraancora
Common names: Anchor coral, sausage coral, ridge coral, bubble honeycomb coral.
Natural Habitat of Hammer Corals
The Hammer coral is commonly found in the Indo-West Pacific, in the waters of the northern Indian Ocean, central Indo-Pacific, Philippines, Australia, Indonesia, Papua New Guinea, and the Solomon Islands.
This species dwells in reef slopes from mid reef to deeper waters and lagoons at depths between 6 – 40m (20 – 131 ft). Large colonies are usually found in shallow environments exposed to moderate wave action.
Description of Hammer Corals
The Hammer coral has a calcified skeletal base, and the colonies have the same skeletal structure as Euphyllia divisa (Frogspawn coral) although the tentacles are quite different.
They are flabello-meandroid with exert septa which plunge near the valley center, the corralite walls emerge from the outer edges; thin & sharp-edged, and there are no collumnae.
These corals are able to completely retract into the skeleton. They have large tubular tentacles with anchor, sausage, or hammerhead-like knobs. The Hammer coral also possess sweeper tentacles of up to 20cm (8 inches).
The color morphs of the long tentacles are brown, blue-grey, green, orange, yellow/gold, blue with the tentacle tips being differently colored, often in shades of green, cream, or white.
In nature, colonies are usually between 20-30 cm (8 – 12 inches) while some can reach over 1 meter (3 ft.).
Hammer corals exist in different varieties:
- the wall type (Euphyllia Ancora).
- the branching type (Euphyllia Paraancora).
The wall Hammer grows as one long and wide skeleton base without any division. Whereas the branching Hammer coral has a phaceloid skeleton and grows individual heads in one body.
Tip: If it is possible, always choose branching Hammer corals. They are more resilient, grow faster, and easier to frag. Other than that both species of the Hammer corals have the same needs and difficulties.
Behavior of Hammer Corals
Hammer corals are known to be aggressive and this is exhibited in their persistent competition with neighboring corals for space and resources (light, nutrient, food). Therefore, it is vital to leave plenty of space in between your hammers and any other coral or tankmates in the aquarium.
Keeping them with their relatives Frogspawn and Torch corals is not a good option. Aggression may still occur and in most cases, Hammer corals will lose the battle.
Note: Torch corals will reduce them to a bare skeleton in no time. Frogspawn corals can be less troublesome but still, it is a risk.
So it’s best to keep these corals in a reef safe tank with only Hammer corals surrounding it.
Corals have developed several specialized mechanisms for protection and competition with others. The defense mechanism of Hammer coral is the sweeper tentacles which has cnidocyte.
This is an explosive cell containing a giant secretory organelle (nematocyst), and this is used to deliver a painful sting to competitors or nearby organisms. The toxin from these stinging cells is capable of burning the coral to the point of either killing it or severely damaging the tissue.
Additionally, the Hammer corals are active throughout the day and partially at night, as they will frequently retract their tentacles to draw in food been fed to them into their mouth.
They also filter-feed by ingesting phytoplankton and other organisms suspended in the water column.
Moreover, it is not uncommon for Hammer corals to become substitute homes for clownfish in the absence of carpet anemones, other organisms that host in the Hammer coral include commensal shrimp species and the hairless orangutan crab (Achaeus Japonicus), although such relationships may turn out to be unfavorable for the coral.
Feeding Hammer Corals
The Hammer corals have a symbiotic relationship with zooxanthellae; an alga living in their tissue. Through this mutualistic relationship, they are able to obtain nutrients through photosynthesis.
Although this specialized feeding mechanism provides sufficient nutrients for their survival, they might also benefit from supplemental feeding.
They can be fed:
- mysis shrimp,
- vitamin-enriched brine shrimp,
- krill,
- plankton
- specialized pellet food,
- copepods,
- reef roids (link to Amazon)
Note: Hammer corals do not take food readily as many other corals species do. However, if you decide to do that, mix the meals with a bit of saltwater and squirt the mixture directly on the head using a turkey baster or sea squirt feeder.
Tip: Turn off the flow, this way it will be way easier to spot feed Hammer corals.
In the established reef aquarium, there is no need to feed them regularly. The most important, DO NOT overfeed them because overfeeding is one of the reasons attributed to the cause of brown jelly infection.
Tank Requirements and Water Parameters
Tank size:
The minimum tank size for housing these corals is 20 gallons (80 liters).
Due to the ability of the Hammer coral to grow over 30 cm (12 inches) in size, and its hostile behavior towards other corals, larger tanks with more capacity/depth are even better as they allow for adequate spacing of the corals and also promotes stability of water parameters.
Water type, Temperature, Hardness, and pH:
Temperature: The optimal water temperature for keeping Hammer corals is between 76-83 °F (24-28 °C).
pH: The ideal pH value is between 8.1-8.4.
Hardness: The Hammer coral will thrive best in tank water with hardness value 8-12 dKH.
Lighting:
The Hammer coral will appreciate moderate lighting conditions for photosynthesis.
Bright lighting aids in the best coloration and healthy growth. However, overexposure can also cause really bad problems as well. So, be careful with that. In addition, these corals need some period of acclimation before being exposed to a higher light.
They enjoy diffused lighting and LED lights are best suited for this purpose as opposed to Metal halides that give off too much heat capable of damaging their tissue. The output from LED lighting around 75-100 PAR value is sufficient for the lighting needs of the corals.
Water flow:
The water flow in reef tanks housing this species should be moderate or fairly low so as to replicate the flow in their natural habitat. Not too much, not too little. It should be good enough to keep detritus from settling on top of the coral.
Regardless of your decision, bear in mind that strong flow can be too harsh and it may damage the corals or make the polyps unable to extend fully or feed properly.
Tip: If the flow exposes the flesh or skeleton of the Hammer corals, it means that it is way too strong.
Care and Maintenance of Hammer Corals
Caring for these corals is not quite challenging and it is something that even beginners can pull off if they want them to thrive for a long period.
Make it a priority to carry out partial water changes of either 20 – 25% monthly, 10 – 15% bi-weekly, or 5% weekly so as to maintain good water quality and replenish the needed trace elements.
Always perform routine water checks to ensure that the water parameters are in their right ranges and proportions.
Keep an eye out on the corals and other tank inhabitants to be sure that they are all in good health condition, if you detect a sick or unhealthy coral, remove it from the display tank and move to another tank for proper treatment till it fully recovers.
Also, try to maintain the following additional water parameters at all times in order to promote the healthy growth of the Hammer corals.
Calcium: 400-450 ppm.
Magnesium: 1,250 – 1, 350 ppm
Salinity/Specific gravity: 1.023 – 1.025
Strontium: 8 – 10 ppm
Phosphate: < 0.05 ppm
Ammonia: 0 ppm
Nitrates: <20 ppm
API REEF MASTER TEST KIT – link to check the price on Amazon
Placement of Hammer Corals in the Tank
Due to the aggressive behavior of these corals, make sure to place corals and other tankmates far from its reach. Maintain adequate spacing of at least 6 – 8 inches (15 – 20 cm) from other corals to curb aggression.
They do enjoy indirect diffused lighting and moderate currents, so put these into consideration when placing them in a reef tank.
Avoid areas of high currents, lateral flow, and direct lighting to prevent possible damages to their delicate tissue.
Furthermore, lower sections of the tank seem to be their sweet spot, where they can be either placed on the substrate or affixed to a live rock.
You should note that placing the corals on a live rock is the better option here as opposed to placement on the sand bed; as sand may get trapped in their calcified base.
Fragging and Reproduction of Hammer Corals
Hammer corals reproduce through sexual and asexual means.
- Sexual reproduction through the release of mature gametes into the water, followed by fertilization and rise of a planula larva that will metamorphose into polyps.
- Asexual reproduction occurs when mature polyps bud off smaller polyps which will form a new colony.
Another means of propagation is through the fragging of a healthy Hammer coral, this has become a very popular means of reproducing corals.
The fragging process is simple for branching Hammer corals.
- You will need a decent-sized, healthy, and lively coral for this purpose.
- Make sure you wear a pair of gloves to protect your hands from possible irritation. Do not touch Hammer corals with your bare hands. Their stings can cause skin rash for a few days.
- Take out the Hammer coral and irritate it a little bit, so that it will retract the tentacles. Otherwise, you can accidentally rip their feeder tentacle off.
- Next, take out the coral and divide it into several parts by cutting through the branching corralites, 2-3 inches (5 – 7 cm) below the head using a band saw.
- Then attach to a frag plug or live rock using cyanoacrylate gel or 2-part epoxy adhesive before placing them back into the tank.
Tip: Take a frag plug and put it in the water for a couple of minutes to release the air bubbles that might be in the ceramic frag plug.
Tip #2: Treat the new frags with an iodine solution (for example, Lugol’s solution) to prevent them from contracting diseases, then you can attach them to a live rock before placing them back into the tank.
Wall type Hammer coral cannot be fragged without damaging the very delicate coral tissue. Even when they are cut with a saw to get the cleanest cut possible, where is a very high chance of failure.
In addition, damaged tissue stresses the coral and they start growing even slower. As a result, in most cases, it is usually not worth the trouble.
Things that you might need depending on your method:
Coral Propagation Fragging Kit Set (link to Amazon) |
Common Problems Associated with Hammer Corals
Brown jelly: This is an infection common to marine corals. It is characterized by a brown jelly-like goo. Unfortunately, it often kills corals so far that we do not have enough time to react.
Brown jelly occurs as a result of poor water quality, tissue damage, overfeeding amongst other factors. You can detect this infection by the presence of a brown jelly floating on the surface of the coral, and it can easily spread to the whole colony or other corals if not treated.
Solution: Brown jelly can be treated by removing the coral from the aquarium and taking it to a different tank or container, brush, and siphon off any visible trace of brown jelly, infected areas (heads) can be fragged to reduce spread, that’s if it is a branching variety by the way.
You can now proceed to dip the unhealthy coral in a freshwater dip (15ppt) or iodine solution to eliminate the infection. Broad-spectrum antibiotics can also be used to cure Brown jelly infection. Afterward, place the treated coral in a quarantine tank to recover fully before returning it back to the main tank.
Lugols Solution – check the price on Amazon
Brown strings: A brown string of material coming out of the Hammer coral is expelled Zooxanthellae. It is often a reaction to stress (poor water quality, lighting, damage, etc.).
Solution: We have to find out what causes stress and fix the issue. Once it is done, Hammer corals will restore the symbiotic relationship with Zooxanthellae.
Flatworms: Flatworms are unwanted hitchhikers. They are known to reproduce rapidly in a nutrient-rich aquarium while hiding in between the coral flesh and bone stalk. They slowly destroy corals and prevent their growth by blocking light from reaching the tissue.
Solution: Proper quarantine and disinfection of new corals for several weeks before putting them in the display tank will help to minimize the risk of introducing flatworms. These hitchhikers can also be tackled using natural predators like the Blue Velvet Nudibranch and Wrasses.
Mishandling: The corals should be handled with care during fragging, placement, and transfer between tanks to prevent the risk of possible tissue damage.
Solution: Do not frag corals with bone crushers as it can injure the fleshy polyp area, you should make use of band saw as it allows for a safer and precise cutting of corals.
Buying Hammer Corals
Getting a good specimen should be your utmost priority, be sure to inspect the coral and avoid buying if you spot any signs of poor health e.g. brown jelly infection, bleaching, and injuries.
Only obtain healthy specimens with a robust body, fully extended polyps, and good coloration.
Hammer coral is popular in the reefkeeping hobby and should be available at local fish stores. They can also be sourced from reputable online breeders.
Note: Do not buy anything in the store if you see Bubble algae, the Glass anemones (Aiptasia), Asterina starfish, or Vermetid snails. Do not risk it!
The Hammer corals come in many different color varieties. They cost about $50 – $200 for a colony, and the price is determined by size, color, etc.
In Conclusion
The Hammer Coral is highly colorful and attractive. These corals can be easily recommended to beginner reefers as their first coral (especially the branching type).
They make a great addition to reef aquariums. Several specimens of this coral can be arranged in the tank to create a unique and fascinating display.
Be sure to provide moderate flow and lighting, and maintain stable water parameters for best growth.
Related articles:
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How to Care for Green Star Polyps
How to Care for Bird’s Nest Corals
Proper Care for Carpet Anemone
How to Care for Zoanthid Corals
How to Care for Acan Corals
How to Care for Torch Corals
How to Care for Frogspawn Corals
How to Care for Elegance Coral
How to Care for Duncan Corals
How to Care for Bubble Tip Anemones
How to Care for Pulsing Xenia
How to Care for Ricordea Coral
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I have three morphs of hammer corals that have gone from an individual frag head to about 4 inches across the hard skeleton (6-8 inches when inflated). They are under LED lights and 150-400 PAR levels.
Apparently, they are capable of withstanding strong light levels if acclimated over time. Enjoyed your article.
Hi James Wedel,
Thank you for the feedback!
Best regards,
Michael