Elephant skin coral

Pachyseris rugosa is a reef-building stony coral recognized by its distinctive folded, plate-like or laminar colonies, with a surface texture of fine ridges and valleys resembling wrinkled skin. Colonies form encrusting to foliaceous structures that can grow into large, layered formations. Like other scleractinian corals, it hosts symbiotic zooxanthellae within its tissues, which provide the coral with energy through photosynthesis while the coral contributes calcium carbonate skeletons that build reef structure.

This structural contribution supports habitat complexity used by fish and invertebrate communities.

The species has a wide distribution across the Indo-Pacific and into the western Indian Ocean, occurring in countries including Australia, Indonesia, the Philippines, Japan, Madagascar, Kenya, Egypt, the Maldives, and numerous Pacific island nations such as Fiji, Palau, and the Marshall Islands. It inhabits marine reef environments, typically on reef slopes and in lagoons at varying depths.

Its population faces pressure from several ongoing threats. Elevated sea temperatures trigger coral bleaching events that disrupt the coral-algae symbiosis. Ocean acidification impairs the coral's ability to calcify and build its skeleton.

Coastal development generates sedimentation that smothers coral tissue, while destructive fishing practices cause direct physical damage to reef structures. Agricultural and urban runoff introduces pollutants and excess nutrients that degrade water quality.

Conservation efforts affecting this species are largely embedded within broader coral reef protection frameworks, including marine protected areas across parts of its range and international monitoring under IUCN Red List assessments. No population trend data are currently available. Given the breadth and persistence of threats affecting coral reefs generally, the species' long-term outlook remains uncertain, with its Vulnerable classification reflecting sustained risk exposure.

Serpent coral inhabits shallow tropical coral reefs and lagoons across the Indo-Pacific, typically growing on reef slopes and flat reef areas at depths of 1-20 meters. It forms encrusting and plate-like colonies on hard substrates, often in areas with moderate water flow and good light penetration.