23 July 2012

Bivalves Unleashed: Bivalve Workshop Day 1

Bivalves are fascinating complicated creatures, I learnt today at the Bivalve Workshop. Although they may appear boring at first glance, looking more closely, they have all kinds of tricks up their valves.
Dr Tan Koh Siang of the Tropical Marine Science Institute is conducting the Workshop: Introduction to Tropical Bivalves over the next week. I attended his fascinating lectures today.

We started with the basics of bivalves. Although 'simple' creatures that lack seemingly 'important' features like a head, bivalves are the second largest mollusc group after the gastropods: snails and slugs. Singapore lies at the heart of an area which among the largest number of bivalve species!
With so many bivalves to discover, identifying them can be tricky. Not all little things with a pair of shells is a bivalve. Dr Tan is pointing at a bivalve 'baby' or larvae, which already has a tiny two-part shell that is in a shape of the letter D, so it's called a D-larva. On the right is another tiny creature with a pair of shells, but it has legs sticking out! It's an ostracod which is a kind of crustacean.
Then there are the Lampshells which belong to their own Phylum Brachiopoda. They are also generally tiny creatures and are not even molluscs.
Fortunately, scientists have figured out all kinds of ways to differentiate the bivalve species, not just using their shells, but also looking more closely at the animal that lives within.
I didn't know that bivalves have a front and back end, and top and bottom side! It's important to sort these out so as to better understand and identify a bivalve.
The inside of the shell has scars where all kinds of muscles attach to close the shell, retract vulnerable parts like the foot and siphon, and more. These scars also help us identify bivalves.
Here's a closer look at the various different kinds of scars on the inside of a bivalve shell.
Dr Tan covered lots and lots of aspects of bivalves which I can't cover in this post. But among the amazing things I learnt today is that some bivalves can be 'furry'. They produce hairs on the shell! And these hairs have different minute structures.
Some bivalves like the Venus clams we often see on our shores produce very fine hairs made out of calcium carbonate on the surface of the shell! The shell of a bivalve is not a simple thing but has complicated internal structures too. Dr Tan explained all this in a way that was quite easy even for ordinary people like me to understand.
Many bivalves also produce long threads to stick onto hard surfaces. Burrowing clams may stick onto buried stones to anchor themselves in the ground.
The variety of gill structures of a bivalve can also help us identify it. And they sure have complicated and curious gill structures!
And different kinds of bivalve tummies!
Bivalves also produce sperm in a bewildering variety of shapes.
'Baby' bivalves can also come in a variety of shapes.
Another curious thing I learnt today was how freshwater bivalves in a stream disperse. In the sea, baby bivalves can float around with the plankton and settle in new places. This method would not work for freshwater bivalves as the stream current flows away from the parents' location into the sea. So many freshwater bivalves brood their young, releasing baby clams with fierce teeth (photos on the left) that emerge to clamp onto fishes! When the fish swims to a suitable location, the clams may release to settle down. Eeks!
Dr Tan also shared more about the complicated and still ongoing business of sorting out the various bivalve groups in the great Tree of Life. He also highlighted that now is the age of molluscs and bivalves, compared to eons ago when life first began. I've certainly gained a new respect for these seemingly humble creatures!
There's so much more to learn from Dr Tan, but alas, the day is almost over. Ivan @VaranusSalvator also live tweeted the lectures #BivalveWorkshop.

There'll be more lectures the rest of the week, which part-timers like me will be eagerly looking forward to. Many of us are volunteers with the Mega Marine Survey. What we learnt today will really help us appreciate and find the bivalves on our shores.

There is also a contingent of full time residential scientists from all over the world who will be more completely immersed in the workshop. They will be going on field trips, doing lab work and learning lots more about bivalves.

We also had a great lunch and fun with the touch pool, but I forgot to take photos of this.

I never knew bivalves were so much fun!

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