Wettstein's Cup Coral

Rhizopsammia wettsteini is a colonial cup coral, though it frequently appears on the reef as distinct, usually solitary polyps. Individual polyps typically measure between 1 and 2 cm (0.4-0.8 in) in diameter. The corallite structure is a solid, opaque yellow, while its semi-transparent tentacles are a vibrant neon-yellow, heavily dotted with tiny white specks. These specks are concentrated batteries of stinging cells (nematocysts). As an azooxanthellate species, it lacks symbiotic algae and does not require sunlight for energy.

This coral inhabits the darkest recesses of reef environments, including the ceilings of caves, deep crevices, and shaded overhangs. It is typically found at depths ranging from 5 to 40 meters (16-130 feet). The coral actively extends its tentacles, particularly during periods of darkness or at night, to capture zooplankton from the water column. Rhizopsammia wettsteini is endemic to the 🌊 Red Sea, where it is adapted to the region's highly saline conditions, and is distinguished from the closely related Indo-Pacific species Rhizopsammia verrilli.