04 November 2009

New record for Singapore! A sea cucumber at Changi

The strange sea cucumber with polka dots that we have been seeing at Changi turns out to be a new record for Singapore!
Polka dot sea cucumber (Holothuria ocellata)
Thanks to Siyang and Lionel for working on this mystery! Their paper (PDF) on this discovery is now online at Nature in Singapore on the Raffles Museum Biodiversity Research website.

A lot of hard work goes into scientific identification of animals. It's not as simple and just looking it up in a book or two. Often a great deal of laboratory work is involved.
For sea cucumbers, it is necessary to examine them internally to be sure of their identity. In particular, to look at their ossicles. These are microscopic pieces of calcium carbonate that are distributed throughout the otherwise soft and squishy animal. In some sea cucumbers, their ossicles can give their skin a stiff and rough texture.

Sea cucumber ossicles come in a wondrous variety of delicate shapes! Each sea cucumber may have several different kinds of ossicles, distributed in different parts of its body. Different species of sea cucumbers have different shaped ossicles in different proportions. So it can be quite a lot of work to properly identify a sea cucumber.
These are the ossicles of our mystery sea cucumber, Holothuria ocellata!

'Ocellata' means eyes and indeed, the sea cucumber does have many eye-like rings on its body. I gave it the lame common name of Polka dot sea cucumber. Siyang has a much nicer common name: the Leopard sea cucumber!

BRAVO! to Siyang and Lionel for undertaking this task to literally unravel our mysterious sea cucumber. Read their paper to learn more about this fascinating animal!

New record of a sea cucumber, Holothuria ocellata (Jaeger, 1833) (Holothuroidea: Aspidochirotida: Holothuriidae) in Singapore. Siyang Teo and Chin Soon Lionel Ng. Pp. 411–414. [PDF, 689 KB]

Siyang first shared about this sea cucumber on his Urban Forest blog, here and here and here.

A few of us shore explorers have also seen this sea cucumber on Changi. Liana also saw one of these at Seringat-Kias, a reclaimed shore. Some of these sightings are consolidated on the wildfact sheet on this sea cucumber.

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