Hammer Coral

Overview

General Description: Hammer Corals are fleshy Euphylliid LPS corals named for their hammer-, anchor-, or T-shaped tentacle tips. Their large polyps sway in gentle flow and can form branching colonies or continuous wall-like skeletons.

Appearance: Long fleshy tentacles extend from branching or meandering corallites. The tips are flattened, curved, or anchor shaped rather than round like frogspawn.

Notable Characteristics: Strong tentacle movement, distinctive hammer-shaped tips, nighttime sweeper tentacles, visible feeding response, and major differences in fragging risk between branching and wall forms.

Natural Habitat

Native Distribution: Widely distributed on Indo-Pacific reefs; the exact range depends on whether the specimen is a branching or wall species.

Natural Reef Habitat: Protected lagoons, reef slopes, turbid inshore reefs, and lower-energy areas with stable hard substrate.

Depth: Commonly shallow to moderate depths, with some colonies in deeper or turbid lower-light habitats.

Natural Lighting: Moderate sunlight, often reduced by depth, turbidity, or reef structure.

Natural Flow: Gentle to moderate surge that moves tentacles without tearing fleshy tissue against the skeleton.

Other Habitat Notes: Fleshy polyps are vulnerable to sediment accumulation and abrasion even when the skeleton is securely attached.

Aquarium Placement

Recommended Placement: Place on lower to middle rockwork in moderate light and broad indirect flow, with open water around the colony.

Space Requirements: Provide at least 6 inches, preferably 6-10 inches, from unrelated corals because sweepers may extend well beyond daytime tissue.

Rock/Sand Placement: Secure to stable rock. Sand placement is acceptable only when the skeleton cannot tip, become buried, or abrade living tissue.

Attachment Method: Use cyanoacrylate gel or reef-safe epoxy on dead skeleton or the frag plug, keeping adhesive away from living tissue.

Orientation: Keep heads upright or gently angled so tissue can inflate freely without rubbing rock and debris cannot settle in the mouths.

Distance From Other Corals: Allow 6-10 inches from unrelated corals and verify spacing after dark when sweepers may be longest.

Other Placement Notes: Hammer, frogspawn, and some closely related Euphylliids may tolerate one another, but compatibility is not guaranteed; monitor every point of contact.

Lighting

Lighting Requirement: Moderate. Strong light is unnecessary and can bleach a newly introduced colony without acclimation.

PAR Range: Approximately 75-175 PAR; start near 100-150 PAR and adjust gradually to extension and coloration.

Spectrum Considerations: A balanced reef spectrum with blue and violet wavelengths supports photosynthesis and fluorescence.

Acclimation Requirements: Begin lower or reduce intensity, then increase exposure over one to several weeks after shipping or a fixture change.

Signs of Too Much Light: Persistent retraction, pale or washed color, bleaching, reduced inflation, or recession on the light-facing side.

Signs of Too Little Light: Dull or browned coloration, excessive reaching, slow calcification, and weak growth despite otherwise stable conditions.

Water Flow

Flow Requirement: Low to moderate indirect flow that gently waves the tentacles without folding or pinning them.

Preferred Flow Pattern: Broad, random, or alternating flow rather than a narrow direct pump jet.

Signs of Excessive Flow: Tentacles remain pinned, tissue whips or folds sharply, polyps cannot expand, or flesh rubs against exposed septa.

Signs of Insufficient Flow: Detritus or mucus settles between heads, food remains on tissue, and extension or gas exchange declines.

Water Parameters

Temperature: 75-80°F (24-27°C)

Salinity: 1.024-1.026 specific gravity (about 32-35 ppt)

pH: 8.1-8.4

Alkalinity: 8-11 dKH, maintained consistently

Calcium: 400-450 ppm

Magnesium: 1250-1400 ppm

Nitrate: Approximately 2-15 ppm; avoid both abrupt nutrient starvation and chronically excessive levels

Phosphate: Approximately 0.03-0.10 ppm; stable measurable phosphate is often preferable to zero

Other Relevant Parameters: Ammonia and nitrite should remain at 0 ppm. Maintain good gas exchange and use testing rather than blind trace-element dosing.

Parameter Sensitivity: Moderately sensitive; abrupt alkalinity, salinity, temperature, nutrient, or light changes can cause retraction, recession, or brown-jelly-like disease.

Stability Requirements: Stable alkalinity and salinity are essential for calcification and tissue health; avoid rapid corrections.

Feeding & Nutrition

Photosynthetic: Yes. Symbiotic dinoflagellates provide much of its energy under suitable lighting.

Natural Feeding: Captures zooplankton, suspended organic material, and small prey with sticky tentacles.

Target Feeding: Optional but beneficial. Offer a small portion near each open mouth with flow reduced briefly and remove uneaten food.

Recommended Foods: Mysis shrimp, enriched brine shrimp, copepods, finely chopped marine flesh, and appropriately sized LPS pellets.

Feeding Frequency: Once or twice weekly is sufficient; avoid oversized pieces and frequent heavy feeding.

Benefits of Feeding: Can support tissue fullness, recovery, calcification, and new-head production in branching colonies.

Special Nutritional Requirements: No special supplement beyond stable calcium, alkalinity, magnesium, balanced nutrients, and appropriately sized food when target feeding.

Growth

Growth Rate: Moderate under stable conditions; branching colonies add heads more predictably than wall colonies expand.

Growth Pattern: Branching hammers bud new heads on separate skeletal branches, while wall hammers extend continuous tissue and skeletal valleys.

Maximum Colony Size: Can become a large showpiece colony with a broad sweeper reach; practical size depends on space and fragging.

Space Requirements: Leave room for full daytime inflation, nighttime sweepers, branch expansion, and maintenance access.

Overgrowth Concerns: It does not encrust rapidly, but can shade neighbors and sting corals well beyond its skeleton.

Aggression

Aggression Level: High toward unrelated nearby corals.

Sweeper Tentacles: Yes. Nighttime sweepers may extend several inches beyond normal daytime tissue.

Chemical Warfare: Physical stinging is the main competitive mechanism; activated carbon and water changes may still help manage dissolved compounds in a mixed reef.

Stinging Ability: Strong and capable of causing rapid tissue damage to many neighboring corals.

Required Spacing: Provide 6-10 inches from unrelated corals and reassess after the colony grows.

Corals to Avoid Nearby: Keep away from SPS, chalices, zoanthids, mushrooms, and other corals that cannot withstand direct Euphylliid contact; also avoid stronger stingers such as Galaxea.

Compatibility

Fish Compatibility: Compatible with most reef-safe fish; butterflyfish, large angelfish, filefish, and other coral pickers may nip fleshy tentacles.

Invertebrate Compatibility: Usually compatible with reef-safe invertebrates, though shrimp and crabs may steal food or irritate tissue.

Coral Compatibility: Suitable for mixed reefs when sweepers cannot reach unrelated corals. Closely related hammer and frogspawn colonies may coexist, but all contact should be monitored.

Potential Predators: Coral-nipping fish, some nudibranchs, and other LPS predators may damage tissue.

Potential Irritants: Vermetid mucus, sediment, food-stealing shrimp, crabs, algae at exposed skeleton, direct pump flow, and nearby aggressive corals.

Fragging & Propagation

Difficulty: Moderate for branching hammer; difficult and high risk for wall hammer

Propagation Method: Cut a branching form through bare skeleton between healthy heads. Wall forms require cutting continuous skeleton and tissue and are best left to experienced propagators.

Tools/Method: Use gloves, eye protection, bone cutters or a coral saw, a separate container of aquarium water, and cyanoacrylate gel for mounting. Keep heat, vibration, and slurry away from tissue.

Healing: Return frags to stable water with moderate light and gentle flow. Branching heads may reopen within days; wall cuts often heal slowly and carry greater infection risk.

Special Risks: Torn tissue, sharp septa, heat damage, brown-jelly-like infection, and rapid recession are major risks, especially with wall colonies.

Safety Considerations: Wear waterproof gloves, eye protection, and respiratory protection when power-cutting skeleton. Control dust and aerosols, disinfect tools, and cut only through clearly exposed skeleton when possible.

Health & Common Problems

Tissue Recession: Common triggers include unstable alkalinity or salinity, tissue abrasion, excessive flow, a neighboring sting, infection, pests, and chronic nutrient imbalance.

Bleaching: Usually linked to excessive light, overheating, or rapid environmental change. Reduce stress gradually and stabilize the system.

Polyp Retraction: Brief closure is normal after disturbance. Persistent retraction suggests unsuitable flow or light, parameter instability, irritation, pests, or disease.

Pests: Flatworms, nudibranchs, vermetid snails, algae, and other hitchhikers may irritate tissue; inspect, dip appropriately, and quarantine new colonies.

Diseases: Brown-jelly-like infections and bacterial tissue loss can progress rapidly, particularly after injury and in wall forms.

Signs of Stress: Persistent closure, gaping mouths, deflated or peeling tissue, exposed skeleton, brown mucus, bleaching, torn flesh, or rapid loss of a head or wall section.

Common Keeper Mistakes: Using direct high flow, placing it too close to corals, making abrupt alkalinity changes, allowing tissue to rub rock, overfeeding, and attempting to frag a wall colony like a branching one.

Recovery Considerations: Correct the cause gradually, improve gentle flow, remove trapped debris, isolate affected colonies, and separate clearly healthy branching heads if infection or recession spreads.

Beginner Suitability

Beginner Friendly: Moderately; branching hammer is the better first choice.

Why: Healthy branching specimens adapt well to moderate light and flow, but require stable reef chemistry and responsible spacing.

Major Challenges: Long sweepers, tissue damage from flow or rock, alkalinity stability, brown-jelly-like disease, and the fragility of wall forms.

Before You Buy

Important Considerations: Determine whether it is branching or wall form. Choose inflated tissue with no brown mucus, torn edges, exposed recent recession, or pests.

Space: Reserve 6-10 inches around the colony and room for future branches or wall expansion.

Lighting: Ask about the seller's PAR or placement and acclimate gradually.

Flow: Choose broad low-to-moderate flow that moves tentacles without whipping or pinning them.

Aggression: Plan around nighttime sweeper tentacles rather than the contracted daytime skeleton.

Parameter Stability: Add only after the aquarium reliably maintains stable salinity, temperature, alkalinity, calcium, and magnesium.

Long-Term Growth: Branching forms can be pruned head by head; wall forms are harder to divide and may need a permanent showpiece location.

Species-Specific Information

Anything important that does not fit above: Hammer Coral is a trade name covering at least a branching and a wall-form species. Branching Hammer is currently placed in Fimbriaphyllia, while Wall Hammer remains in Euphyllia. This distinction matters because branching colonies can usually be cut through bare skeleton between heads, whereas wall colonies have continuous tissue and are much riskier to frag.