Page 114 - Science Class 06

Endoskeleton: It is an internal skeleton largest group in the animal kingdom that
present inside the body of a living organism, has an exoskeleton made up of a substance

e.g., a bony or a car laginous skeleton of called chi n. Their wings are a ached to the
vertebrates. All vertebrates like birds, fish, exoskeleton through muscles. Exoskeleton
rep les, amphibians and mammal have an does not grow with the body. It is shed by

endoskeleton. The endoskeleton is the the insects several mes during their life
internal support system that provides cycle in a process called mol ng.
structural support and protec on to the Skull
internal organs and aids in the movement
Skull is a hard structure made up of small
and locomo on. Furthermore, it also
bones. It forms the cranium and the face.
provides sites for the a achment of
Cranium protects the brain.
muscles and thus can transmit the forces to
the muscles. Skull is formed by 22 bones out of which 8
bones are fixed together to form the
The endoskeleton mainly comprises of
cranium and 14 bones fuse to form the face.
bones and car lage. In some organisms like
car laginous fishes, it is exclusively made The only bone which has movable joint is

up of car lage. Bones are made up of bone the lower jaw. This movable joint is
cells known as osteoblasts and they form supported by muscles and ligaments.
joints to ar culate with each other. A bone Skull placed on the top of the backbone can
is a ached to another bone by ligament be moved up, down and sidewards.

and muscles are a ached to bones by
tendons.

Exoskeleton : The exoskeleton is the
external skeleton that exists on the outside
of an organism. It is the hard outer coa ng
that provides support to the body and

protects the muscles and so ssues or
organs of the body. It also protects the
animals from predators and harsh environ-
ment. Exoskeletons developed from the

ectoderm. Some common examples of
Human Skull
exoskeleton include scales, calcified shells
and chi nous cu cle. Spine or Backbone

Most of the invertebrates or animals that Spine or backbone consists of 24 separate
lack backbone have exoskeletons, e.g., differently shapes. Bones a ached to a
grasshoppers, cockroaches and crustaceans triangular, curved bone at the bo om. Spine

like crabs and lobsters. Insects are the starts from the neck and extends throughout

114 Science-6