ACROPORA

Acropora –

Acropora is one of the most species-rich genera of scleractinian (stony) corals, comprising over 150 described species. They are characterized by rapid linear extension rates and contribute disproportionately to reef accretion across the Indo-Pacific. Colonies display high morphological plasticity, ranging from corymbose and tabular forms to arborescent and hispidose structures. Their skeletal architecture is composed of aragonite and features distinct axial and radial corallites; the axial corallite governs apical growth and is a hallmark diagnostic trait for the genus. Because of their relatively thin coenosteum and high surface-area-to-volume ratio, Acropora species are among the most physiologically sensitive corals to thermal stress, disease, and ocean acidification.

Identification Summary (Scientific)

• Axial corallite present at branch termini; tubular, usually larger than radial corallites.

• Radial corallites vary by species (immersed, appressed, nariform, dimidiate, etc.) but are generally small and densely arranged along branches.

• Coenosteum typically porous with fine spinules.

• Colony morphology highly variable but often branching, tabular, or corymbose with fast apical extension.

• Polyp distribution uniform; tissues often thin compared to other genera.

• Coloration highly variable and not a reliable diagnostic feature.

Distribution

Acropora has a broad Indo-Pacific distribution, spanning the Red Sea, Indian Ocean, Southeast Asia, the Coral Triangle, and across the western and central Pacific to French Polynesia and the Line Islands. Species richness peaks in the Coral Triangle, particularly Indonesia, the Philippines, and Papua New Guinea. A smaller number of species occur in the tropical western Atlantic (e.g., A. palmata, A. cervicornis, A. prolifera).
They occur primarily in shallow reef environments (1–25 m), especially upper reef slopes and reef flats where wave action and high irradiance promote rapid growth, although some species extend into mesophotic zones (>30 m). Their distribution is strongly influenced by sea surface temperature, water clarity, and carbonate saturation state.