Shells belong to the animal art “soft animals”. This art is divided into eight parts. In the shell-part (Bilvalvia) there are 7000 arts.
Typical for shells is that they have two
shell-parts that are articulated together by an elastic ligament. Because
of this ligament, the shell opens when the scale relaxes. It has an
articulated body, which is surrounded by the shell and a mantle. It has a
symmetric body shape. The shell is like an outer skeleton, which protect
it against beasts of prey and bad environment conditions.
The oldest part of the shell is the growing centre for the scale,
and is called UMBO. Most of the scales got a few pair of teeth, so the
shell-parts keep together. To close the shell-parts fast is very important
for all sorts of shells. Inside
of the shell you will find the MANTEL, which protect the inner organs.
Kamskjell