Welcome to the Physogyra genus landing page. In this section, you will find general information about this genus and tips on how to identify it. If you are looking to confirm an observation made with the Coral Finder about a Physogyra with large daytime extended polyps, use the image browser below to identify what you saw underwater. Then choose the following links for further comparison with similar genus: Plerogyra.
- 1 species
- Coral Finder p. 9, 27
- COTW – Vol 2 p. 92-93
Found in the Indo-Pacific.
Physogyra forms massive colonies, which are commonly found in protected, shaded areas with turbid waters.
The corallites are arranged in meandering valleys with shared walls. The septa are large, smooth and widely spread, forming a regular blade-like arrangement. The valleys are generally hidden by grape-like bubbles (vesicles), and at night tentacles are extended.
The large day-time expanded polyps and thick, smooth septa are characteristic of the Euphyllidae.
(slide show with photos of tentacles and vesicles retracted.)
The Coral Finder lists Physogyra in two key groups with Plerogyra being a potential candidate for confusion.
Similar genera to Physogyra with large daytime expanded polyps (Coral Finder p27)
Physogyra can be confused with Plerogyra but they may be easily separated by examining the corallite arrangement; Plerogyra forms valleys with separate walls, whereas Physogyra’s valleys have shared walls. If these structures are hidden by vesicles, waft your hand over the colony; Plerogyra’s vesicles will retract slowly, whereas those of Physogyra will retract more rapidly, exposing the colony surface.
Similar genus: Plerogyra
- Euphyllidae family page
Suggested Reading – Identification Tools
- Veron, J. E. N. (1985). Corals of Australia and the Indo-Pacific. Sydney: Angus and Robertson.
- Veron, J. E. N. (2000). Corals of the World. Melbourne: Australian Institute of Marine Science.
- Veron, J. E. N., & Pichon, M. (1980). Scleractinia of Eastern Australia. Part 3, Families Agaraciidae, Siderastreidae, Fungiidae, Oculinidae, Merulinidae, Mussidae, Pectiniidae, Carophylliidae, Dendrophylliidae. Australian Institute of Marine Science Monograph Series, IV, 471.