ABSTRACT
Vertebrates are a major group of animals that are fairly well understood and have evolved complex body systems that enable them to compete effectively with and dominate other groups of animals. The complex action of the different vertebrate body systems is coordinated by relatively advanced nervous and endocrine systems. It is this complexity that makes vertebrates quite noticeable since they are able to perform rapid and complex movements, produce a variety of sounds and exploit the different niches in water, air and on land. It was recognized long back by the Greek physician and scientist Claudius Galen (130-200) that a living organism is not a summation of body parts but an indivisible unity.
