“Every
naturalist has his favorite example of an awe-inspiring
adaptation. Mine is the ‘fish’
found in several species of the freshwater mussel Lampsilis.
Like most clams, Lampsilis
lives partly buried in bottom sediments, with
its posterior end protruding. Riding atop the
protruding end is a structure that
looks for all the world like a little fish. It
has a streamlined body, well-designed side
flaps complete with a tail and even an
eyespot. And, believe it or not, the flaps
undulate with a rhythmic motion that imitates
swimming.”