[muawiyah]

Just did a quick check. You ask a good question. The answer is "invasion" ~ people and animals have been hauling these critters around to lakes and rivers for millions of years. The result is everything you could imagine.

Recently you've had African freshwater clams show up in Europe, and European clams in America, and American clams in Australia and Australian clams in China, and so on.

What a mess. And some of them are all male, and others are all female, and some of them just don't care.

No doubt there are doctorates waiting to be printed.

[colorado tanker]

What a mess. And some of them are all male, and others are all female, and some of them just don't care.

LOL!

The Zebras have arrived here. DOW is fighting to keep them out of our rivers and lakes, but IMHO it's probably a losing fight.