“Surrounding
the fish, symmetrically on both sides, are extensions of the
mantle, the ‘skin’ that encloses the soft
parts of all clams and usually ends at the
shell margin. These extensions are elaborately
shaped and colored to resemble a fish, with a
definite, often flaring ‘tail’ at one end and an ‘eyespot’ at
the other. A special ganglion located
inside the mantle edge innervates these flaps. As the
flaps move rhythmically, a pulse,
beginning at the tail, moves slowly forward to
propel a bulge in the flaps along the entire body.
This intricate apparatus formed by the
marsupium and mantle flaps, not only looks like a
fish but also moves like one.”