Our Dynamic bones

No. Not all. Very tiny animals like amoeba do not have any bones. Bigger animals with more than one cell, but not too many cells, can also survive without any skeleton. E.g. Hydra, Jellyfish do not have bones.

Do all big animals have bones?

Some animals like Squid and shark have no bones. They can be as long as 35 feet in body length. Squids have an endoskeleton, an internal supporting, strong structure of Calcium salts.It is hard and rigid. Sharks have an endoskeleton of cartilage alone and have no bones though they are vertebrates.

How many bones do we humans have?

We, adult humans, have 206 bones in our body.

Where are they located?

Nearly all parts of our body have them. The skull and face have 28, the adult backbone has 26 of them.

The number of bones of the rib cage is 25. Each of our limbs has 30 bones. The shoulder girdle has 4 and hip girdle has 2.That makes it 205 in all and there is a single bone called HYOID on inner side of the mandible, that is the lower jawbone. The hyoid is U shaped and is not connected to any other bone or cartilage. This is a unique feature of hyoid as all other bones are attached to either a bone or a cartilage.

What is the shape of bones?

The bones differ in shape. Most of them are long rod like. A few are flat like a table. Bones called vertebrae, which form our backbone, are irregular in shape.

What are they made of?

The bones are made up of an organic cement like ground substance; the protein called OSSEIN and salts of Calcium. Rods of calcium salt are fixed in the proteinous matter giving strength like the mixture of cement-concrete.

What is the structure of bones?

Human bones show at rim connective tissue (periosteum) and a few rings of cells called osteoblasts. The osteoblasts lay down the bone. The bone has in its center the soft part, bone marrow. Between the bone marrow and the periosteum lies the substance of the bone. Around small cylindrical Haversian canals which contain blood vessels lie cells of bone trapped in the matrix laid by the osteoblasts. The cells around the Haversian canals are the osteocytes. They are arranged in concentric circles called Haversian lamellae.

An Haversion canal in center, with many Haversion lamellae around forms a unit called Osteon.

Is the bone alive?

Yes. Most people seem not to appreciate this fact, but the bone is very much a live tissue.

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