Physophyllia

Lore & Background

Physophyllia ayleni forms colonies with encrusting or stratified plates. The plates have vertical walls of irregular height that radiate toward the plate margins, separating individual corallites or small groups of corallites, which are consequently widely spaced. Its color ranges from dark grey to dark brownish-green. Some specimens reach 1 m in diameter, but colonies of 20–30 cm are more common.

The species was first described by John W. Wells in 1935. It was originally thought to belong to the family Pectiniidae, but was reclassified in 2014 to the family Merulinidae. However, as of 2026, the Integrated Taxonomic Information System still includes P. ayleni in Pectiniidae, reflecting ongoing taxonomic uncertainty.

It lives in coral reefs located in tropical waters near the coast, found in most reef habitats except areas with strong currents. It typically occurs at depths between 2 and 25 m. The species is native to Australia, Cambodia, the Philippines, Indonesia, Japan, Malaysia, Papua New Guinea, Singapore, the Solomon Islands, Taiwan, Thailand, and Vietnam.

Reader's Guide

Physophyllia ayleni is significant as the sole species of its genus, representing a distinct lineage within the Merulinidae family. Its hermatypic nature means it actively contributes to reef construction in the Indo-Pacific, a region of high coral biodiversity. The species' morphological traits—encrusting or stratified plates with irregular vertical walls and widely spaced corallites—distinguish it from other merulinid corals. Its color range from dark grey to dark brownish-green and typical colony size of 20–30 cm provide practical identification cues. The taxonomic history of P. ayleni is notable: originally placed in Pectiniidae, it was reclassified to Merulinidae in 2014, yet as of 2026 the Integrated Taxonomic Information System still lists it under Pectiniidae, highlighting persistent taxonomic disagreement. Ecologically, it occupies most reef habitats except those with strong currents, at depths of 2 to 25 m, and relies on mutualistic zooxanthellae for nutrition—the algae perform photosynthesis, providing oxygen and sugars to the polyps while feeding on the coral's metabolic waste products. Its wide distribution across 13 nations underscores its adaptability within tropical coastal waters.

Did You Know?

• Physophyllia is a monotypic genus, meaning it contains only one species: Physophyllia ayleni.
• It was reclassified from the family Pectiniidae to Merulinidae in 2014, but as of 2026 ITIS still lists it in Pectiniidae.
• It contains mutualistic symbiotic algae called zooxanthellae, which perform photosynthesis and feed on the coral's metabolic waste.