Acropora millepora
A variable-colored branching coral from shallow Indo-Pacific reefs.
Acropora millepora is a branching stony coral that forms small, clumped colonies with short, cylindrical branches. Its radial corallites are uniform in size and feature projecting lower rims, which give them a scale-like texture. The coral’s color varies widely, appearing as green with orange-tipped branches, pale pink, orange, plain green, or blue. First described in 1834 by Christian Gottfried Ehrenberg under the name *Heteropora millepora*, this species is native to the western Indo-Pacific, occurring in shallow waters from the east coast of Africa to Japan and Australia. It is common across its range, which extends from the Red Sea, Kenya, and South Africa to India, Malaysia, Japan, Indonesia, and Australia, typically growing between two and twelve meters deep on reef flats, upper reef slopes, and in lagoons. Ecologically, *Acropora millepora* is zooxanthellate, hosting symbiotic dinoflagellates in its tissues. Its larvae prefer to settle on vertical surfaces and encrusting coralline algae, though at lower temperatures (22.5 °C) they become less selective about settlement sites and show reduced survival rates. Interestingly, the local strain of symbiont—even before infecting the larvae—can influence their choice of substrate. The main threat to this species is the destruction of its reef habitat. As a shallow-water coral, it is vulnerable to bleaching and disease, and it is also collected for the aquarium trade. Rising sea temperatures and ocean acidification pose additional risks to corals generally, leading the IUCN to list *Acropora millepora* as "Near Threatened."
Quick Facts
- Taxon
- Acropora millepora
Facts from the source article.
Lore & Background
Acropora millepora is a small colonial coral that grows in clumps with short, cylindrical branches. The radial corallites are all the same size and have projecting lower rims, giving them a scale-like appearance. Its colour is variable and may be green with orange tipped branches, or pale pink, orange, plain green or blue. This species is common in the western and central Indo-Pacific, ranging from the Red Sea, Kenya and South Africa to India, Malaysia, Japan, Indonesia and Australia. It grows in shallow water between two and twelve metres deep, mostly on reef flats, but also on upper reef slopes and in lagoons. Acropora millepora is a zooxanthellate species, harbouring symbiotic dinoflagellates in its tissues. Its larvae preferentially settle on vertical surfaces and on encrusting coralline algae. At lower temperatures (22.5 °C), larvae were less specific in their choice of settlement sites and had lower survival rates. The choice of substrate for settlement was modified by the strain of symbiont present in the locality, even though the larvae had not yet been infected.
Reader's Guide
Acropora millepora is a zooxanthellate coral, meaning it harbours symbiotic dinoflagellates in its tissues that provide energy through photosynthesis. It is a common species in shallow Indo-Pacific waters, typically found between two and twelve metres deep on reef flats, upper reef slopes, and in lagoons. Its larvae preferentially settle on vertical surfaces and on encrusting coralline algae, though at lower temperatures (22.5 °C) they become less selective and show reduced survival. Interestingly, the strain of symbiont present in the local environment influences larval settlement choice even before infection occurs. In the reef ecosystem, this coral contributes to structural complexity and provides habitat. The main threat to Acropora millepora is the destruction of coral reefs where it lives. As a shallow-water species, it is susceptible to bleaching and coral diseases. It is also collected for the reef aquarium trade. Corals in general are expected to be impacted by rising sea temperatures and ocean acidification, leading the IUCN to list Acropora millepora as Near Threatened.
Did You Know?
- Acropora millepora was first described in 1834 by Christian Gottfried Ehrenberg as Heteropora millepora.
- At lower temperatures (22.5 °C), larvae were less specific in settlement site choice and had lower survival rates.
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