Acropora gemmifera
Brook, 1892
Colonies from the western Indian Ocean and Red Sea have distinctive colours and skeletal structures.
Description: Colonies are digitate. Branches are thick, tapering to a small axial corallite. Radial corallites are of two sizes, usually in rows. The larger sized corallites increase in length towards branch bases, where incipient axial corallites are common.
Color: Usually purple, blue (which may photograph pink), cream or brown, with blue or white branch tips. Dark grey with white corallite rims and yellow axial corallites in the western Indian Ocean.
Habitat: Exposed upper reef slopes and flats.
Abundance: Common.
Similar Species: Acropora humilis and A. monticulosa, the latter having radial corallites of uniform length down the sides of branches.
Source reference: Veron (2000). Taxonomic references: Veron and Wallace (1984), Wallace (1999). Identification guides: Veron (1986), Nishihira and Veron (1995).
The typical appearance of digitate branches. Zanzibar, Tanzania Photograph: Charlie Veron
A large colony exposed to wave action. Madagascar Photograph: Charlie Veron
Showing the increase in size of radial corallites down the sides of branches. Great Barrier Reef, Australia Photograph: Valerie Taylor
Skeletal detail. Radial corallites.
Surface detail of a plate. Madagascar Photograph: Charlie Veron