Acropora grandis
Brook, 1892
This species shows wide geographic variation.
Description: Colonies are arborescent, with thick upright to prostrate branches. They may form stands 7 metres across. In shallow water branches are short and compact, while in deeper water colonies have more open branches. Radial corallites are of mixed sizes and shapes; those near branch tips are long and tubular and similar to axial corallites. Branch tips are very soft and readily crushed.
Color: Usually dark reddish-brown with pale branch ends. Other colours include blue, purple and green, usually with paler branch ends.
Habitat: A wide variety of environments, especially upper reef slopes and lagoons.
Abundance: Common.
Similar Species: Acropora formosa, which has similar but smaller corallites, does not have elongate radial corallites near branch tips and does not have branch tips that are as readily crushed. Acropora nobilis is smaller and has rasp-like, not tubular, radial corallites.
Taxonomic note: This species is divisible into several smaller semi-distinct taxonomic units. Source reference: Veron (2000). Taxonomic references: Veron and Wallace (1984), Wallace (1999). Identification guides: Veron (1986), Nishihira and Veron (1995).
A large colony of irregular prostrate branches. Ryukyu Islands, Japan Photograph: Charlie Veron
A branch tip. The tubular radial corallites are of irregular size. Apo Island, Philippines Photograph: Charlie Veron
The common appearance of colonies in shallow water. Calamian Islands, Philippines Photograph: Charlie Veron
Skeletal detail. Radial corallites.
Detail of a branch tip with multiple axial corallites. These are usually lightly calcified and easily crushed between fingers. Houtman Abrolhos Islands, Western Australia Photograph: Charlie Veron