Stony Coral

zooxanthellate

Colonies reach several metres across when fully grown. They are basically hemispherical, but in moderately or strongly sedimented conditions tend to develop thick, upward growing columns. Important comparative features are that in P. lutea the septal triplet fuse to form a trident, and calices are smaller and walls usually thicker than in P. solida. Also, calices have five or six large pali which help to distinguish this from P. solida. This species is very widespread. It is at its most abundant in sheltered areas such as on back reef slopes of patch reefs and in bays, where huge colonies cover over 75% of the substrate over thousands of square metres, between the surface and 15 m deep. These colonies tend to be columnar in shape, a condition which seems to be initiated by sedimentation into depressions of the surface of the coral and death of the covered sections (Sheppard, 1998). Colonies are hemispherical or helmet-shaped and may be very large. The surface is usually smooth. Colour: usually cream or yellow but may be bright colours in shallow water. Abundance: very common and occurs with P. lobata and P. australiensis on back reef margins, lagoons and fringing reefs (Veron, 1986). Characteristic of the massive species, which are difficult to tell apart. Colonies are hemispherical, often very large, and may be undercut at the base. The outer surface may be loosely folded in flat mounds and ridges but is smooth in texture. Corallites are 1-1.5 mm in diameter. Colour: usually varies from pale grey to yellow, lime-green or pink. Habitat: shallow lagoons, where they may form micro-atolls, and fringing reefs (Richmond, 1997).