Biologic evolution

The photograph of littleneck clam's hinge is taken.

It is understood to be different from ark shell's shape.

Littleneck clam's shell is strong adhesion.

The shell doesn't open with seawater entered the shell in which it died.

The shell doesn't open even if it makes efforts and it pulls it.

The opening method opens when the shell is dropped to the floor.

I think that the filling pull of the tide of hunting and the relation of the
shell are interesting themes.

It is imagined that time that the shell can be sealed up is limited.

Therefore, the time sealed up and physical strength might be supported by putting the body
in sand.

By the filling pull of the tide

When the tide pulls it, the sand pit in the sea becomes hard.

The thing that becomes hard might be convenient for the littleneck clam.