Tuesday, July 12, 2011

Atlantic Coquinas: Seeing In a New Way

Earlier this morning I walked eastward on the beach, into the morning sun. Alone. I left the house where Charlie was absorbed on his mom's 'big phone' (iPad) and Lulu and Caroline were still in bed. I love walking barefoot on hard wet sand with water rushing over my feet. A steady breeze, a big sky. A good beginning to the day. After twenty minutes of steady walking, I turned back and, with the sun behind me, I began to notice what had been obscured by the sun's brightness.
I became conscious of the tiny bi-valves burrowing into wet sand and in an instant, making what look like tiny volcanos, spewing water and sand.
I noticed a gull planted firmly on a stretch of wet sand about twenty yards from me, unmoving. Was the gull waiting to snack on these creatures when they surfaced? Did they sense my footsteps?
Back at the beach house, I found the name of these small bi-valves with two clicks of a mouse: Atlantic Cocquinas or Donax variabilis.

On Scienceray I read, "They [Atlantic Cocquinas] move up and down the beach with the movement of the tide. The water gives them a lift, first up the beach and then back down. When they fine the spot they are looking for, they quickly bury themselves in the sand.

Coquinas like to hang out with each other. Where you find one, you can find many others forming colonies of clams. They align themselves vertically in the sand, which means they can pack themselves into the sand quite nicely."

And from the Shell Museum.org I learned the following:

"In order to remain in their terrain near the surf line where the sand is always wet, the coquinas move up and down the beach as the tide goes in and out. They accomplish this by monitoring the vibration of waves on the sand. When the tide is coming in they emerge from the sand and hitch a ride to shore, digging in to prevent being washed back out to sea. If they end up too far from the water, they sense that the sand is dry and hop back on the next wave to allow themselves to be pulled further out to sea.

If uprooted, they use their foot to quickly burrow back below the surface of the sand.
"Children are fascinated by the speed at which these little creatures move in order to bury themselves in the sand. They seem to mimic a gymnast, standing on their head, using their large foot to wiggle and wriggle into the sand with lightning speed. This has been coined the 'dance of the coquinas'."

Now this information is all well and good, But what I really learned this morning as I stood quietly and watched the movement of the Atlantic Coquinas is that enormous and constant movement takes place as these tiny bi-valves surface and then burrow back into the sand, leaving an explosion of geyser of water and sand and then a simple round hole. Several waves later, they may or may not emerge and the process repeats itself. Imagine the continuous movement of sand as the Atlantic Coquinas dive deep, displacing minute patches of beach.
I began to notice that as I approached clusters of these tiny be-valves that they quickly dove beneath the sand. could they sense the vibrations of my footsteps? Perhaps. I began to think about the impact that we have on even the tiniest of creatures. I stood absolutely still, like the gull who was motionless on the sand, waiting for the return of the Atlantic Coquinas.

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