The
skeleton (from Greek σκελετός,
skeletós "dried up") is the body part that forms the supporting structure of an
organism. There are two different skeletal types: the
exoskeleton, which is the stable outer shell of an organism, and the
endoskeleton, which forms the support structure inside the body. There are also two other forms of skeleton referred to, the
hydroskeleton and the
cytoskeleton.