Hammer Coral (Euphyllia ancora)

Taxonomy & Identity

The Hammer Coral, also known as Anchor Coral, is named for its distinctive T-shaped or anchor-shaped tentacle tips. A close relative of Torch and Frogspawn corals, it shares many care requirements while offering a unique aesthetic. Hammer Corals are beloved for their hypnotic swaying motion and come in a stunning array of colors.

Natural Habitat & Distribution

E. ancora is distributed throughout the Indo-Pacific, from the eastern coast of Africa to the western Pacific islands. It inhabits protected reef areas, lagoons, and slopes at depths from 3 to 40 meters. Colonies prefer areas with moderate light penetration and gentle to moderate water movement.

Morphology & Growth Forms

Hammer Corals grow in two primary forms: branching and wall. Branching varieties have separate corallites on individual branches, while wall hammers feature corallites arranged along a meandering wall structure. Tentacles are thick and fleshy with flattened, hammer or anchor-shaped tips. Colors include green, gold, orange, purple, and various combinations with contrasting tips.

Lighting Requirements & Spectrum

• Intensity: Low to moderate
• Target PAR: 50–150

Hammer Corals are photosynthetically capable and adapt well to various lighting conditions. They thrive in moderate light and may bleach or retract under intense illumination. Position in the lower to middle regions of the tank. Blue and actinic lighting enhances fluorescence and brings out the best coloration.

Flow Requirements & Patterns

• Intensity: Low to moderate
• Type: Indirect, oscillating

Gentle, indirect flow allows the polyps to extend fully and sway naturally. Avoid strong direct currents that can cause tissue damage or prevent extension. Random flow patterns work well. The coral should move gently with the current but not be battered or constantly deflected.

Nutrient Dynamics & Water Chemistry

Stability is more important than hitting exact numbers. Hammer Corals can adapt to various conditions but suffer from rapid parameter swings. Moderate nutrient levels support good coloration. Consistent alkalinity supplementation promotes healthy skeletal growth.

Feeding Biology & Symbiosis

Hammer Corals contain symbiotic zooxanthellae that provide most of their nutritional needs through photosynthesis. They are also effective heterotrophic feeders with strong prey capture capabilities.

• Mysis and brine shrimp
• Finely minced meaty foods
• Coral pellets and powders
• Amino acid supplements

Weekly target feeding enhances growth and color intensity. Broadcast feeding can also be effective as the large polyps readily capture suspended particles.

Common Diseases, Pests & Predators

• Euphyllia Eating Flatworms – inspect and dip all new specimens
• Brown Jelly Disease – rapid tissue necrosis requiring immediate intervention
• Tissue recession from unstable parameters or excessive light/flow
• Bristleworms may irritate polyps if populations are large

Quarantine and prophylactic dipping are essential. Regular inspection helps catch problems early. Maintain stable parameters and appropriate placement to prevent stress-related issues.

Compatibility & Placement

Hammer Corals are aggressive and deploy sweeper tentacles at night that can reach several inches beyond their daytime footprint. They will sting and damage most neighboring corals but typically coexist peacefully with other Euphyllia species.

• Best zone: Lower to middle tank on stable rock
• Give space: 6+ inches from non-Euphyllia corals
• Compatible: Can be placed near other Euphyllia with caution

Fragging Techniques

Branching Hammers can be fragged by cutting through the skeleton between heads using a band saw or bone cutters. Wall varieties require cutting through the wall structure, which is more challenging. Ensure each frag has adequate skeleton and at least one healthy polyp. Allow several weeks of healing in moderate conditions before final placement.

Aquacultured Strains & Trade Names

Popular varieties include "Gold Hammer" with vibrant yellow-gold coloration, "Toxic Green" featuring intense green fluorescence, "Orange Hammer" with warm orange tones, and various bi-color morphs. Australian specimens are particularly valued for unique colors and patterns. Wall hammers with unusual colors command premium prices.

Difficulty Rating & Summary

Difficulty: Beginner to Intermediate

Hammer Corals are rewarding LPS corals suitable for most reef aquariums. Their moderate care requirements, beautiful movement, and diverse color options make them popular choices. Success comes from stable parameters, appropriate placement, and vigilance against pests.