Skeletons and supporting systems

Skeleton is the bony framework of the body which provide support, shape, rigidity and protection to the soft tissue and organ in animal. The skeleton of any animal depend on the position of the organism in the evolutionary trend help to determine the advancement and development of organism e.g. man is able to stand erect than other organism due to their sophisticated skeletal build up.


  1. Cuticle:

Cuticle is composed of protein called chitin and a thin waterproof layer of wax. Chitin is a non-living substance, hence animal with this type of skeletal structure undergo moulting or ecdysis. Cuticle is an exoskeleton which is located externally on the body of the animal. Examples of organisms with this kind of the body structure are mainly Arthropods e.g. insect, crab, scorpion, prawn and crayfish.

  1. Bones:

Bones consist of a living bone cell called osteocytes, protein fibres called collagen and minerals which are mainly of calcium phosphate and calcium carbonate. A bone consists of a hard outer layer called shaft and a spongy or hollow cavity filled with bone marrow. Animal that has bones include bony fish, toad, lizard and mammals.

III. Cartilage:

A cartilage is a tissue found in the skeleton of complex vertebrates. It consists of living cell called chondroblast, carbohydrate and protein fibre. It is a very tough and flexible tissue that has great tensile strength. Examples of organisms which possess cartilage are: cartilaginous fishes such as: Shark, rays and mammal.

Types of cartilage.

  1. Hyaline cartilage : Trachea, bronchi and surface of moveable joint, nose.
  2. Fibro- cartilage: between inter vertebral column.(c) Elastic cartilage: ear, epiglottis.

Types of skeleton.

  1. Hydrostatic of fluid skeleton.
  2. Exoskeleton.
  3. Endoskeleton.

Hydrostatic Skeleton is a type of skeleton possessed by soft bodied animal examples of organism with this type of skeleton are earthworm and sea anemones.

Exoskeleton is a type of skeleton which is found outside or external part of the body of some animals. Most invertebrates do possess cuticle which is composed of chitin.

Endoskeleton is the type of skeleton which is found inside the body of the animal. Endoskeleton exists in toad, lizard, birds and mammals.

Endoskeleton in mammal include the skull, the vertebral alumni or backbone, ribs, and the bones of the fore and hind limbs.

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