Clams

This is our back pond.

In the fall it attracts its fair share of leaves. And when it gets warm algae begins to bloom. And thus this past weekend I donned my muck boots and headed in. And while scooping the fruits of my labor, the aforementioned algae and leaf muck, into a wheelbarrow for disposal, I noticed a small shell.

It was a clam. A tiny clam. And then I noticed another. And another.

So I grabbed a small aquaria, as a school teacher Patty has a bunch, filled it with water, and began to pick through the muck for clams.

There were lots of tiny clams.

And they were very active, moving about the tank (you can see the center clam has its foot out) and siphoning for food.

I transferred a couple to a tank with cleaner water to take pictures. Here is a shot with the foot more obvious (as with any image, click to bigafy):

Here is an image of an empty shell, with a dime for scale.

I told you they were tiny.

Both our ponds are man made with the back pond being the more natural of the two. I understand how frogs (and tadpoles) and turtles and snakes found their way there. They hopped or crawled or slithered. But clams? While that foot works great in water I doubt it would do too well for the quarter mile or so from the nearest lake or stream.

My reference works and field guides are silent on the subject of clams. And the interwebs were little better. While I did discover that these are known as "fingernail clams" (FnCs) I learned little else. Other than some are native and some are not.

It's a puzzlement.

Update: Patty found this page on the web. I found this bit especially interesting:

The concept of a barely-half-inch wingless, aquatic critter starting out in mid-country and taking over America (and the world) is fairly astonishing, no matter how much geologic time you give it, but it turns out that FnCs “think outside the pond.” They attach to water plants as tiny juveniles, and the water plants attach to the feet of water birds, and water birds DO have wings. Sometimes the clam-ettes clamp directly onto feathers, amphibians, or mobile aquatic insects (clam and clamp both derive from Old English “clamm,” “to bond or fetter”). In addition, some species of FnC are ingested by ducks but not digested, and they may be regurgitated alive at some distance from home.

So maybe they hitched a ride on these?