Animal Diversity Introduction PDF

An Introduction to Animal Diversity  GENERAL CHARACTERS OF ANIMALS 1. Exhibit multicellular construction 2. Composed of eukaryotic cells 3. Nutrition is by ingestion(Holozoic) 4. Nervous tissue and muscle tissue are unique to animals 5. All animals, and only animals, have Hox genes...

An Introduction to Animal Diversity  GENERAL CHARACTERS OF ANIMALS 1. Exhibit multicellular construction 2. Composed of eukaryotic cells 3. Nutrition is by ingestion(Holozoic) 4. Nervous tissue and muscle tissue are unique to animals 5. All animals, and only animals, have Hox genes that regulate the development of body form. Although the Hox family of genes has been highly conserved, it can produce a wide diversity of animal morphology  6-Most animals reproduce sexually, with the diploid stage usually dominating the life cycle. 1-After a sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage. Cleavage Zygote Eight-cell stage 2- Cleavage leads to formation of a blastula. Cleavage Cleavage Blastula Zygote Eight-cell stage Blastocoel Cross section of blastula 3- The blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues Blastocoel Endoderm Cleavage Cleavage Blastula Ectoderm Archenteron Zygote Eight-cell stage Gastrulation Gastrula Blastocoel Blastopore Cross section of blastula  Classification of Animal Kingdom 1.3 million living species of animals have been identified. They are classified according to the following bases: Level of Organization Type of Body Symmetry Type of Body Cavity Embryonic Development