'Naked' corals of Singapore

This corallimorpharian (Corynactis sp.) with tentacles and mouth protruding was found at Pulau Ubin as part of a study to establish the diversity and distribution of corallimorpharians in Singapore.

When the tide recedes along Singapore’s seashores, not many animals are as inconspicuous as the corallimorpharian, which forms slimy blobs when emerged. However, when submerged, these anemone-like creatures spread open their oral discs, exposing the upturned mouths, tentacles and intricately-textured discs that can have very distinct and beautiful forms. They are neither hard coral, soft coral nor anemone, but have been dubbed ‘naked’ corals for their close affinities to stony corals, and for how coral reefs could look like as the oceans acidify under climate change, stripping hard corals of their skeletons.

Because of their inconspicuous nature, our understanding of their biodiversity has been very poor, until Ms Oh Ren Min, an NUS Bachelor of Environmental Studies undergraduate student embarked on a study in 2018 to document these animals as part of her Undergraduate Research Opportunities Programme in Science project. She worked under the supervision of Assistant Professor Huang Danwei from NUS Biological Sciences and collaborated with citizen scientists to establish the diversity and distribution of corallimorpharians in Singapore.

The researchers employed an integrated approach, combining both morphological and DNA sequencing methods to accurately identify species. Based on local field collections and observational data generously shared by citizen scientists, the team discovered six species and characterised each of them in detail. Two of the species, Corynactis sp. and Discosoma sp., are likely new to science.

Results from this study were published in the Raffles Bulletin of Zoology on 15 May 2019. In addition to uncovering the diversity of this enigmatic group of organisms, these findings highlight citizen science as a promising approach to support conventional survey methods for characterising marine biodiversity in Singapore.