Acropora humilis

Dana, 1846


This species shows wide geographic variation.

Description: Colonies are digitate. Branches are thick, tapering to large dome-shaped axial corallites. Small branchlets or incipient axial corallites usually occur at the base of main branches. Radial corallites are of two sizes, the larger are usually in rows and have thick walls and only slightly increase in size down the sides of branches.
Color: Many colours, but most usually cream, brown, purple or blue (which may photograph purple) with blue or cream tips.
Habitat: Exposed upper reef slopes and reef flats.
Abundance: Usually common, and sometimes a dominant species.
Similar Species: Acropora gemmifera, which has small axial corallites and radial corallites increasing in length down branches. See also A. monticulosa and A. torresiana.

Source reference: Veron (2000). Taxonomic references: Veron and Wallace (1984), Wallace (1999). Identification guides: Veron (1986), Nishihira and Veron (1995).

Showing large axial corallites. Great Barrier Reef, Australia Photograph: Ed Lovell


This species is common on intertidal outer reef flats. Great Barrier Reef, Australia Photograph: Ed Lovell


Branch tips. Papua New Guinea Photograph: Neville Coleman


Skeletal detail. Axial and radial corallites.
Based on Australian Institute of Marine Science data