When some people think of skeletons, they think of Halloween or some mad scientist's display in a laboratory. But we all have a skeleton. It is what gives our bodies shape and form. Without a skeleton, we would be a heap of skin and muscles.
The skeleton is made of a series of bones. The key feature of all animals with bones is that they have a set of bones known as the vertebrates which travel along the spine. In fact, animals with bones are called vertebrates and animals without these bones are called invertebrates.
So what are bones? Bones are largely made of calcium and other minerals. They are hard enough to support our weight and daily stress. Bones protect our major organs and give our bodies shape. Bones are actually living tissue. The center of the bone, or marrow, is where your blood is created.
The bones in children actually grow and change. The human body has 206 bones which make up the skeleton. Six of those are tiny bones found in the inner ear, three in each ear.
How We Move Our Bones
Our bones are not able to move on their own. They require something to pull them in order to be useful. Attached to many of the bones are fibroustissues known as tendons. They are slightly elastic and have a white or gray color.
Tendons connect bones to muscles. Muscles contract and relax as needed to help our bones — and the arms, legs, head, feet, etc. they support — move.
Tendons do not have any blood vessels and so take a long time to heal if damaged.
Between some of our bones we have joints that allow the body to bend like our elbows and our knees.
These special connections between the bones are covered with a plastic-like material that protects the ends of the bones from rubbing together. This material is called cartilage. Cartilage also makes up our outer ear and the end of our nose.
Protecting our brain is the bone known as the skull. The skull is a special set of bones and plates that when we are born are separated by cartilage, but as we grow the cartilage dissolves away and is replaced by the growing skull bone. Without this unique system, the skull bones would collide with each other as they grew.
The animals known as vertebrates make up the animals we call mammals, fish, birds, reptiles, and amphibians. Each of these animals has a backbone and a skeleton. Birds have bones that are hollow — this makes their bones lighter for flight.
While vertebrates all have skeletons to give their bodies shape and support, invertebrates have no bones. Many of the invertebrates have an exoskeleton, or a hard outer shell, as their skin to act like bones do.
Insects, crabs, lobsters, and shrimp are a few of the creatures with exoskeletons. Other invertebrates are soft like the octopus, squid or earthworm.