Tuesday, June 4, 2013

'Sulphur-eating' clams, shrimps and sea cucumbers: Mini-talks at the Southern Expedition

The highlight of the day are the mini-talks by experts at the Expedition. From 'sulphur-eating' clams, to wondrous shrimps and amazing sea cucumbers.
The series kicks off with a talk on "Chemosymbiotic bivalves" by Drs John Taylor and Emily Glover, The Natural History Museum, London UK.

Dr Taylor explained how the discovery of 'sulphur-eating' clams in deep sea vents changed the way people studied clams. These fascinating clams were also found in other deep sea habitats like sunken wood and the bones of dead whales that fall to the bottom of the sea.
These deep sea clams had bacteria in their gills which could convert sulphur into nutrients that the clams could use. Soon it was discovered that many other clams including shallow water ones had similar relationships with such bacteria.
Drs Taylor and Glover are particularly interested in the clams in this family that have these bacteria. Dr Taylor points out the special one with tubular thingies through which the clam sucks up sulphur rich stuff to 'feed' its bacteria.
These interesting clams are found in all kinds of places from the intertidal to the deep sea.
After searching hard, the good Doctors found their sought after clams at the artificial lagoon of Seringat-Kias! As well as other bivalves too.
Next, we learn more about shrimps in the talk "Biodiversity of caridean shrimp" by Dr Sammy de Grave, University of Oxford, UK and Dr Arthur Anker, National University of Singapore. These often small creatures can be colourful and there are lots and lots of different kinds.
Dr Sammy jokes that these prawns are boring and that if we find one we should just eat it.
There are many kinds of shrimps that live with a wide variety of animals. Alas, Dr Sammy did not find those he expected while in Singapore. Oh dear.
Snapping shrimps are of course fascinating. Being able to produce such forceful snaps that can stun prey and crack shells with one enlarged pincer.
While snapping shrimps belong to Family Alpheidae, there are other families with member than can snap. Like this machine gun shrimp that is found in corals. It can snap with both pincers!
Dr Sammy shares lots and lots of colourful photos. Here's a selection of some of them. This motivates me and Pei Yan to redouble our efforts to find more shrimps tomorrow!
Dr Sammy pre-empts the question: what is the difference between a prawn and a shrimp? Scientifically this is not a meaningful distinction. While in Singapore prawns may refer to those that we can eat, and shrimps to those not usually eaten, in other countries these terms may refer to different kinds of 'shrimps'.
We learnt more about sea cucumbers in the talk "Aspidochirotid sea cucumbers in the collections of the Research Center for Oceanography, LIPI Jakarta" by Ms Ismiliana Wirawati, LIPI, Indonesia.
She shares details of some special sea cucumbers found in Indonesia. In the process showing what goes into identifying sea cucumbers. These soft squishy animals that usually become totally flat when preserved, are identified by the shapes of the tiny bits of skeleton found in their bodies. It is tedious work. Many sea cucumbers can look similar when alive and they are difficult ID precisely just from a photograph.
As  usual, the talks are just the tip of the iceberg. It whets the appetite to learn more! There will be another session of evening talks tomorrow.

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