Chapter 8 Support Chapter 8 Support and Movementand Movement

Chapter 8 Support Chapter 8 Support and Movementand Movement

8.1 Support systems in Animals8.1 Support systems in Animals

Prepared by: C.K. Ong

What is a support system? Why do animals need a support system?

Before answering these questions, look at Figure 8.1 (page 76) to see what happens when an elephant is without its support system.

The support system is very important to all animals.

Without a support system, the body would just collapse.

The elephant, for example, will not have any particular shape.

It would not be able to raise its body above the ground, and therefore would have great difficulty walking on land.

1. All living things need a support system to support soft body tissues.

2. Humans and land animals have support systems which enable them to stand erect and move.

3. The support system in humans and animals is known as the skeleton.

4. There are three types of support systems in animals. They are the

(a)exoskeleton

(b)endoskeleton

(c) hydrostatic skeleton

8.1 Support System in Animals

1. Crabs, prawns, snails and millipedes have exoskeletons. An exoskeleton is a hard, outer skin or shell.

2. Function of exoskeletons:

Exoskeleton

(c) protect the soft parts inside the body.

(b) support the weight of the body

(a) maintain the shape of body

1. The human and vertebrate skeletal system is an endoskeleton.

2. The functions of the endoskeleton are

(a) to support the weight of the body.

(b)to maintain the shape of the body

(c) to protect the soft organs inside the body such as the brain, heart, lungs and spinal cord.

(d)To allow the muscles in the human body a place to attach themselves.

(e)To enable the limbs to move.

Endoskeleton

1. Some invertebrates such as the earthworms, leeches and caterpillars have soft bodies. These organisms have hydrostatic skeletons.

2. The hydrostatic skeleton is a muscular wall that encloses the body cavity of the animal.

3. A fluid fills the body cavity of the invertebrate. This fluid pushes out in all directions. This supports and shapes the body.

Hydrostatic skeletons

4. Functions of the hydrostatic skeleton:

(a)Supports and maintains body shape.

(b)Supports and protects internal tissues and organs.

(c) Allows invertebrates to bend, straighten and move.