What is a skeleton?
For many of us, the word "skeleton" is a clear association with the medical sciences or horror films. About what it is, read our article.
The word "skeleton" comes from the ancient Greek "dried", which etymologically explains its meaning: previously, animal skeletons were made using drying under the rays of the sun or in hot sands. Roughly speaking, the skeleton is what supports the body of the vertebrate from the inside in a certain state, and the invertebrate - from the outside, performing primarily musculoskeletal functions.
Scientists believe that the oldest of the skeletal beings found was a sponge-like (its fossil) found inhabiting the coast of Australia over 550 million years ago! Even then, the animals possessed - albeit primitive - a skeleton.
- The exoskeleton - external - is characteristic of invertebrates (shells) and arthropods (chitinous shell). In these formations on the body of animals do not contain cellular organisms.
- The endoskeleton - internal - in vertebrates consists of a complex of dense formations (bones that are connected by cartilage or fibrous tissues). It is the passive part of the musculoskeletal system.
- A hydrostatic skeleton (where fluids play a supporting role) is observed in some polyps.
The skeleton performs many functions of a mechanical and biological nature and forms the basis of the movement apparatus. It serves as a framework for softer tissues. It also performs the functions of protecting the spinal cord and nervous system in vertebrates (for example, in humans) from mechanical and other damage. And the chest is the vital internal organs: the heart, lungs and stomach. And also - and biological functions of metabolism.