First discovered in 1822, the sponges grew so large—a meter or more in both height and diameter—that their cup-like structures were sometimes used as tubs for babies. But their size made them valuable to collectors around the world and they were overharvested until they disappeared from Singapore in the 1870s. The last time living sponges were seen was 1908, when collectors found some in West Java, Indonesia. The species was then thought to be extinct.
But in the 1990s, a few dead Neptune's cup sponges turned near Australia, giving researchers hope that they might find these massive Porifera again in the oceans around Singapore.
And now that hope has been met: Two living Neptune's cup sponges have been found near Singapore's St. John's Island. The first specimen was found in March by biologists with the environmental engineering firm DHI Water & Environment (S) Pte Ltd. A second sponge was found 50 meters away.
"When we came across the sponge, we knew immediately that this was something very different," marine biologist Karenne Tun said in a prepared release from DHI.
Writing for My Green Space, the newsletter of Singapore's National Parks Board, Tun and fellow biologist Eugene Goh said the sponges were "pale yellow to white, and resembled shallow bowls standing on robust stalks. Unlike other sponges found in Singapore waters, the Neptune's cup sponge felt firm and leathery."
Sponge expert Lim Swee Cheng, author of the book A Guide to Sponges of Singapore, was called in to identify the two animals as members of the long-lost species. "My heart skipped a beat when I saw it in Singapore waters this year," Mr. Lim recently wrote on his Facebook page.
Neither of the sponges have reached the epic, meter-high height and diameter of legend—both are described as "young" and are only 30 centimeters in diameter—but they will now be studied in their natural environment to find out how they grow and how to conserve them.
Some assumptions about the species are already proving false. Previously thought to be a slow-growing species, the two sponges actually grew several centimeters between April and August, said Tun.
Meanwhile, the scientists hope to find more of the sponges out there. "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," Tun told Straights Times. "More importantly, [it] points to the possibility of adult populations present within Singapore's coastal waters."
Photo 1: One of the recently rediscovered Neptune's cup sponges, courtesy of DHI Water & Environment. Photo 2: A 1925 image of a Neptune's cup sponge being used for a child's bath