10 May 2012

Cunning Clam Escape at Changi

How does a hapless clam get away from the voracious Noble volute?
The Noble volute (Cymbiola nobilis) is a large handsome snail that feeds on clams and snails. This one seemed to have found a nice juicy Mactra clam (Mactra mera). Is the clam doomed to be breakfast?

Like many bivalves, this burrowing clam has a large strong foot. It uses its foot to dig into the ground and pull itself in. But to get away from the snail, the clam uses its foot to literally hop away. But that's not all!
I noticed, the clam didn't hop straight ahead but sort of made a U-turn, to land beside the snail but some distance away. "Wheredidgo?!" the Noble volute seems to be saying, as it waved its long siphon around. The volute uses its siphon to 'sniff' out edibles and is probably trying to sense where its breakfast went.
I was quite astounded to see the snail head in the opposite direction from where the clam was. The clam did kind of go that way for a bit, before it made a U-turn. Did the clam lay some sort of 'smell' trail to fool the volute?
Wow! So much more to discover about our marine life!

James saw a more successful Noble volute grab a clam!

Here's more about what I saw on Changi today.

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