The Ruffled Coral
Merulina is a genus of large-polyp stony coral in the family Merulinidae, found across the Indo-Pacific from the Red Sea to the western Pacific. It is immediately recognizable by its distinctive growth form — thin, blade-like or scroll-like plates arranged in ruffled, layered patterns that maximize surface area for light capture. In good conditions, Merulina colonies develop a three-dimensional architecture unlike almost any other coral.
Identification
Merulina ampliata is the most commonly encountered species, forming thin plates and scrolls with a corrugated surface. The corallites (individual polyp skeletons) are small and arranged in short, irregular valleys — giving the surface a finely textured appearance. Wild colonies are typically brown, tan, or pale green; aquacultured specimens can show vivid green and yellow fluorescence under blue light.
The thin, blade-like growth form distinguishes Merulina from Goniastrea and Platygyra, which form more massive, dome-shaped colonies. Merulina’s skeletal plates are often thin enough to be translucent when held to light.
Natural Habitat
Merulina is found at depths of 2–25 meters on protected reef slopes and in lagoons where moderate flow and moderate-to-high light are available. It is more common in slightly deeper, calmer water than many other LPS corals, where its thin, light-capturing plates are an advantage over the compact morphology of massive brain corals.
Reef Aquarium Care
Lighting: Moderate lighting suits Merulina well — PAR 75–200. Its thin, layered growth form is an adaptation for low-light efficiency, so it does not need the intense lighting required by Acropora.
Flow: Low to moderate, indirect flow. Merulina’s thin plates can be damaged by strong direct flow. Random, tumbling flow is ideal.
Placement: Mid to lower tank, on a stable base where the fragile plates will not be knocked over. The growth form makes it susceptible to toppling in high-flow environments.
Feeding: Responds well to weekly target feeding with small meaty foods. More so than compact brain corals, Merulina seems to benefit visibly from supplemental nutrition.
Frequently Asked Questions
Is Merulina hard to keep?
Moderate difficulty. More sensitive than Goniastrea or Platygyra but easier than Acropora. Stable parameters and indirect flow are the key requirements.
How fast does Merulina grow?
Moderate growth rate — faster than massive corals but slower than branching SPS. Under good conditions, colonies can add several centimeters of new plate growth per year.