This mystery large pink sea cucumber has been identified as Holothuria (Stauropora) fuscocinerea!
Thanks to Siyang, Lionel and Kok Sheng!
The sea cucumbers in Singapore are insufficiently documented. Even large sea cucumbers that are frequently encountered have remained a mystery. So I'm delighted that the three gentlemen have taken the time to sort out this one.
It's quite tedious to identify sea cucumbers, because positive identification requires a really close look at the hard bits inside these squishy animals. Called ossicles, these microscopic bits come in wondrous shapes and designs.
And these are the ossicles of our mystery sea cucumber! Aren't they fascinating?!
This sea cucumber is widespread in the tropics. In Singapore, we have seen it on the reefs of our Southern shores, while the animal in the study was found at Tanah Merah! (The shore sadly has been hit by the recent oil spill). It is not often encountered, possibly because it is usually well hidden in rubble, reef or rocks. It seems to be less shy at night. For those I've seen, it is usually alone.
We've seen some of these spit out white sticky cylindrical 'tubes' when stressed. These are called Cuvierian tubules. These sticky and sometimes toxin strings immobilise the disturber in a gummy mess or release toxins. The sea cucumber eventually regrows its arsenal of Cuvierian tubules.
As usual, I haven't thought of a very good common name for the sea cucumber. If you can think of a better common name, please share by commenting!
Thanks once again to Siyang, Lionel and Kok Sheng for sorting out this sea cucumber's identity!
Read the paper on Nature in Singapore on the Raffles Museum of Biodiversity Research website: Teo, S., C. S. L. Ng & K. S. Loh, 2010. New record of a sea cucumber, Holothuria (Stauropora) fuscocinerea Jaeger, 1833 (Holothuroidea: Aspidochirotida: Holothuriidae) in Singapore. Nature in Singapore, 3: 133–137. [PDF, 1.10 MB]
See also posts by Kok Sheng and Siyang about the sea cucumber and the paper.