Dipsastraea Lacuna

Overview

Dipsastraea lacuna, commonly known as the knob coral, is a stony coral species found exclusively in the Red Sea. It forms substantial, massive colonies that can grow to over one meter in width.

Distribution & habitat

This species is endemic to the Red Sea. It thrives in shallow reef environments, typically at depths between 1 and 15 meters, where it prefers clear water and areas exposed to wave action.

Appearance

The colonies of Dipsastraea lacuna are characterized by crowded, circular to irregular corallites with separated walls. These walls are typically beige to brown, contrasting with the white centers, or columellae, of the corallites. The inner walls of the corallites plunge vertically, and the septa—the internal ridges—are thin, uniformly spaced, and subequal. A narrow groove, known as an ambulacral groove, exists between adjacent corallites because their outer ridges, or costae, do not meet. The species lacks paliform lobes and features small, compact columellae.

Biology & behavior

Like many other stony corals, Dipsastraea lacuna is a zooxanthellate species, meaning it relies on a symbiotic relationship with photosynthetic algae (zooxanthellae) living within its tissues to produce energy from sunlight. While it was historically classified under the genus Favia, it was reassigned to Dipsastraea in 2014, though it is still frequently referred to by its former name in many contexts.