Finger Coral

Overview

Acropora humilis, commonly known as finger coral, is a widespread species of stony coral characterized by its robust, digitate growth form. It is frequently found in shallow, high-energy reef environments where it often serves as a dominant component of the local coral community.

Distribution & habitat

This species is widely distributed across the tropical Indo-Pacific, ranging from the Red Sea and the Indian Ocean to the central and western Pacific, including Australia and Hawaii. It typically thrives in exposed areas such as upper reef slopes and reef flats, where it is systematically subjected to strong water currents.

Appearance

Colonies form dense, bush-like structures composed of thick, tapering branches. A key identifying feature is the presence of large, dome-shaped axial corallites at the tips of these branches. The radial corallites are organized in two distinct sizes, with the larger ones often arranged in rows. The coloration is highly variable, commonly appearing in shades of cream, brown, purple, or blue, frequently with contrasting cream or blue branch tips.

Biology & behavior

Like many other members of its genus, A. humilis is a hermaphroditic broadcast spawner, releasing gametes into the water column for external fertilization. It maintains a symbiotic relationship with photosynthetic algae, which provide a significant portion of its nutritional requirements. While it can reproduce sexually, it also utilizes asexual fragmentation to expand its local population, allowing new colonies to develop from broken pieces of the parent structure.