SUPPORT SYSTEMS IN ANIMALS AND PLANTS

Ms. T.J. MkhizeUniversity of Johannesburg

There 3 types of skeletons

1. Hydrostatic skeletons- lack hard parts)

2. Exoskeletons- external hard parts

3. Endoskeletons- internal hard parts

Different types of skeletons

A hydrostatic skeleton consists of fluid held under pressure in a closed body.

This is the main type of skeleton in most cnidarians, flatworms, nematodes, and annelids.

Annelids use their hydrostatic skeleton for peristalsis, a type of movement on land produced by rhythmic waves of muscle contractions.

Hydrostatic Skeletons

Examples of hydrostatic skeleton

NEMATODE FLATWORMS ANNELIDA

An exoskeleton is a hard encasement deposited on the surface of an animal

Exoskeletons are found in most molluscs and arthropods

Arthropod exoskeletons are made of cuticle and can be both strong and flexible

The polysaccharide chitin is often found in arthropod cuticle

Exoskeletons

EXOSKELETONS

MOLLUSC

ARTHROPODS

An endoskeleton consists of hard supporting elements, such as bones, buried in soft tissue.

Endoskeletons are found in sponges, echinoderms, and chordates.

A mammalian skeleton has more than 200 bones.

Some bones are fused; others are connected at joints by ligaments that allow freedom of movement.

ENDOSKELETONS

ENDOSKELETONS

SPONGES ECHINODERMATA CHORDATA

THE HUMAN SKELETON

There are two type of human skeleton

1.Axial skeleton2.Appendicular skeleton

The human skeleton

Axial skeleton

Axial skeleton

Consist of 28 bones It consists of flat bones that are connected on the

sides by immovable joints called sutures. In babies not all the bones of the skull make contact

with each other and fontanels are formed. The lower jaw bone (Mandible) is the only movable

bone of the skull – Upper jaw (Maxilla) is not moveable.

The large opening at the base of the skull is called the foramen magnum – it is where the spinal cord enters the skull.

Human skull

Human skull

Consists of 33 bones called vertebrae. 24 vertebrae are individual single bones. 9 vertebrae are fused to form the sacrum and

coccyx. Cartilage disks are found between vertebrae. The s-shaped structure of the vertebral column and

the disks absorb shock and help to protect the spinal cord.

The first vertebrae – Atlas – carry the weight of the skull, allows the head to nod.

2nd vertebrae – Axis – allows head to move to the side

Vertebral column

7 Cervical vertebrae

12 Thoracic vertebrae

5 Lumbar vertebrae

5 fused vertebrae = sacrum

4 fused vertebrae = coccyx

Vertebrae is divided into

Consists of the sternum, 12 pairs of ribs and thoracic vertebrae.

It protects the heart and lungs. First 7 pairs of ribs are directly attached to the

sternum by cartilage – called true ribs. Next 5 pairs – false ribs – last 2 pairs of false

ribs are not attached to the sternum – called floating ribs

Intercostal muscles found between ribs – aid in breathing process.

Thorax

Thorax

True ribs

False ribs

sternum

Floating ribs

Made up of the shoulder (pectoral girdle), arms, hips (pelvic girdle) and legs.

126 bones. Function: Movement

APPENDICULAR SKELETON

Pectoral girdle and arm

Pelvic girdle and leg

Support Movement Protection Blood cell production Storage Endocrine regulation

FUNCTIONS OF A SKELETON

Support in land vertebrates

Support in land vertebrates

The backbone of four - legged land vertebrates such as the camel

and the horse either curve upwards or downwards.

The curve enables the backbone to withstand the heavy load acting

on the animal

Big land animals such as elephant and the rhinoceros need strong

and big pectoral and pelvic girdles to support their body weight

. Big animals that have short legs with larger cross sections are

more stable and can also support a heavier load.

Support in aquatic vertebrates

The support system of aquatic vertebrates is not the same as land

vertebrates because life in water is very different from life on land.

Aquatic vertebrates such as whales and dolphins have smaller

and lighter endoskeletons than land vertebrates.

This is because a large part of their body weight is supported by

water buoyancy. Water buoyancy helps aquatic animals to move

in water.

Support in aquatic vertebrates

Support in aquatic vertebrates

The pelvic girdles of many aquatic vertebrates are

very small of non-existent.

They are adapted only for swimming in water.

Whales have small skeletons when compared to their

body size because a large part of their body weight is

supported by water buoyancy.

Anas,M.(2012).Support and Movement.http://www.slideshare.net/anasyem/support-and-movement1

Campbell,N.A.,Reece,J.B. 2010.Biology Eighth Edition Pearson International. 50-701-713.

Unversiti Teknologi Malaysia.(2013). Support system in animal.

http://www.slideshare.net/anasyem/support-and-movement1

Reference