And while snakeheads have indeed popped up in half a dozen states besides Maryland, they've done so in modest numbers.

CNN: Fish tale

Such clumsy locomotion does not lend itself to wanderlust, and snakeheads in a good pond are likely to stay there forever.

CNN: Fish tale

But, like snakeheads, they are only part of the explanation for Morecambe.

ECONOMIST: Why did 19 Chinese cockle-pickers drown in Morecambe Bay?

The snakeheads are probably the most ruthless and businesslike of the people-smugglers.

BBC: More

"Snakeheads are extremely lazy and sedentary, " says Hawaii biologist Ron Weidenbach.

CNN: Fish tale

Snakeheads, however, are really nothing more than common swamp fish.

CNN: Fish tale