Stylaraea

Lore & Background

Stylaraea punctata is described as probably the smallest of the zooxanthellate corals, being circular, encrusting, and usually less than 1 cm in diameter. The polyps are flower-like and less than 1 mm across, each having twelve tentacles. The cup-shaped corallites have a solid central columella and poorly-developed calcareous septa in two whorls of six. The colouring is usually pale brown or purple with white septa and columella.

This coral is native to shallow tidal pools in tropical parts of the Indian and Pacific Oceans. Its known distribution includes widely separated locations such as East Africa, the Seychelles, Indonesia, the Great Barrier Reef, and Guam. It is possible that it is present in other locations as it is easily overlooked. Its habitat is shallow tidal pools seldom more than half a metre deep, just above the sediment and hidden under dead pieces of coral or under massive coralline algae, where it suffers little competition from other coral species.

The IUCN lists Stylaraea punctata as 'Data deficient' due to insufficient evidence to judge its status and whether any conservation measures are required. Like other corals, this species is likely to be affected by a rise in sea temperature and ocean acidification due to climate change, and as a result be more susceptible to coral diseases.

Reader's Guide

Stylaraea is significant as a monotypic genus within the family Poritidae, represented solely by Stylaraea punctata. Its primary distinction is being probably the smallest of all zooxanthellate corals, a characteristic that makes it easily overlooked in its natural habitat. The species is found in shallow tidal pools across the tropical Indo-Pacific, from East Africa to Guam, but its actual distribution may be wider than currently known due to its inconspicuous size. The coral occupies a specific ecological niche just above the sediment, hidden under dead coral or coralline algae, where it faces little competition from other corals. Its conservation status is listed as 'Data deficient' by the IUCN, reflecting a lack of information needed to assess its risk. However, like other corals, it is considered vulnerable to rising sea temperatures and ocean acidification from climate change, which could increase its susceptibility to diseases. The legacy of Stylaraea lies in its role as an example of a minute, specialized coral that may be more widespread than records show, and whose status remains uncertain due to insufficient data.

Did You Know?

• Stylaraea punctata is probably the smallest of the zooxanthellate corals, usually less than 1 cm in diameter.
• Each polyp of Stylaraea punctata has twelve tentacles.
• The coral is known from widely separated locations including East Africa, the Seychelles, Indonesia, the Great Barrier Reef, and Guam.