Home > Marine > CRISP PILLOW CORAL- A coral living on the ‘EDGE’

Found only in the warm tropical waters of the Indian Ocean, the crisp pillow coral Anomastraea irregularis is a rare endemic. Most people snorkeling around the reef don’t see it because it is so small. It forms flat, encrusting colonies or mound-like structures that can grow up to 20 centimeters high in shallow waters. Despite its small size, it has a tall tale to tell. First, it is the only species in its genus which means if this species disappears, the whole genus becomes extinct. Being in a monospecific genus (the only species in the genus) also suggests that it has a different evolutionary path from other coral families and species.

Crisp pillow coral is categorized as an Evolutionarily Distinct and Globally Endangered (EDGE) species and in urgent need for conservation. Poorly studied, the ecology and habits of this coral are not well-understood. The International Union for the Conservation of Nature (IUCN) has it listed as Vulnerable on its Red List. The IUCN red list is a database that provides information on the global status of species facing high risk of extinction.

It grows at the base of shallow reefs with tidal pools where it is sandy with turbid water. Colonies are found at depths of two to 18 meters where light is available. As a zooxanthallate, the crisp pillow coral lives in symbiosis with a microalgae within its tissue which photosynthesizes and provides it with energy. The species therefore can only grow in areas with sufficient light for the microalgae to photosynthesize. However, the coral also feed through its tentacles which are normally extended out during the day unlike most species of coral that have their tentacles retracted during the day. Found in shallow tidal pools exposes it to damage such as people trampling on it to being smothered by algae.


Corals secrete calcium carbonate. A coral reef is made of thin layers of calcium carbonate. Coral polyps form a living mat over a calcium carbonate skeleton. Coral reefs are home to a quarter of the world’s marine species. They have numerous functions such as protecting the coastlines from eroding into the sea to providing fishers with fishing grounds. Scientists are studying how corals and coral reefs are likely to change with climate change. Increasing sea surface temperature because of climate change is altering their symbiosis with the algae and exposing them to other damaging factors such as coral diseases and pollution. Understanding the habitats and structure of species of corals like the crisp pillow coral can provide an insight on how corals are likely to adapt to stress. This can help to design a roadmap to conserving it. Setting up marine protected areas that are properly managed is important. Everyone needs to act responsibly to save the seas by reducing waste, pollution and carbon emissions because they affect the water and life within.