‘Extinct’ sponge back from the dead
by Grace Chua
Once, the enormous Neptune’s Cup sponge was common in Singapore waters, its metre-high, chalice-like form a popular trophy for collectors.
It could be found in water from Thailand to Indonesia and as far afield as Australia. In 1822, the Neptune’s Cup was the first sponge described from Singapore after Sir Stamford Raffles landed.
The second colonial Resident of Singapore John Crawfurd even called it one of “the strangest and most fantastic forms of organic life” ever seen.
Yet for more than a century, it had not been seen locally and was thought to be globally extinct, until one was dredged up off Australia in 1990.
But in March this year, local researchers found a young Neptune’s Cup (Cliona patera) alive and well in the waters off St John’s Island. It was only the second time anyone had ever seen live Neptune’s Cups in situ, in the wild. The first time was in 2000 off Thailand, but that specimen was not studied.
Sponges are primitive animals, and some luxury bath sponges are actually the dried skeletons of some sponge species.
Adult Neptune’s Cups have been used as bathtubs for children.
The months of research that followed the find were chronicled in a post yesterday in the Raffles Museum of Biodiversity blog at https://rafflesmuseum.wordpress.com/
Biologist Karenne Tun, a senior marine biologist at research and consulting organisation DHI Water & Environment, was part of the team that first spotted the sponge during a routine survey dive.
“For us, it’s really exciting because it’s an iconic species for Singapore,” she said.
On a second dive in August, they found not one but two young Neptune’s Cups about 30cm in diameter.
“The presence of two young Neptune’s Cup sponges within a surveyed area of 50m by 50m signals hope that more are present within the area, and more importantly, points to the possibility of adult populations present within Singapore’s coastal waters,” Dr Tun said.
That also suggests there are pockets where the environmental conditions are suitable for this rare species to survive, she added.
“It was indescribable,” said the sponge expert Lim Swee Cheng of the Tropical Marine Science Institute, who identified the sponge based on a small sample and followed the researchers on their August dive.
Previously, all existing information on the Neptune’s Cup came from dead museum specimens. There are some 200 sponge species around Singapore waters.
Now, the researchers have planned another dive for December, and aim to study how the sponges grow and live.
There have already been some surprises. For instance, a small wedge was cut from one sponge for a research sample.
By August, the sponge had grown back, and put on a few centimetres.
“The Neptune’s Cup was thought to be a very slow-growing species,” said Dr Tun. “Looks like we might have to rethink some of these ideas.”