Good Luck Clam

I have been in France for a week. I wanted to sketch the River Dordogne. I was looking for the autumn colours. I was hoping to see lots of autumn leaves floating down the river. For some reason there were not many. Downstream the river was in the late afternoon sunshine. Where I was sitting it was soon hidden by the limestone cliffs: not many leaves and soon not much sunshine. Walking along the shore I found small brown clam shells. I was not sure what they were. Fresh water clams. Later I identified them as the Good Luck Clam. Good luck for me, not such good luck for the local variety, who are being wiped out by these non natives. Corbicula Flumea was brought to America with Asians in the 19th century. They were first seen on the River Dordogne in 1980. No wonder they are invasive. A single self fertilising individual of these rather dull, muddy shell fish can produce between 35,000 and 47000 baby clams a year. Self fertilisation! Where do they get the time?