Click on a lesson name to select. Chapter 24 Introduction to Animals Section 1: Animal Characteristics Section 2: Animal Body Plans

24.1 Animal Characteristics Animal Features Introduction to Animals Chapter 24  The ancestral animals at the beginning of the evolutionary tree are eukaryotic and multicellular.

Adaptive Radiation They developed adaptations in structure that enabled them to function in numerous habitats.

Feeding and Digestion Introduction to Animals  Animals are heterotrophic.  The structure or form of an animal’s mouth parts determines how its mouth functions Animal Characteristics Chapter 24

Support Introduction to Animals  Invertebrates  Exoskeletons  Hard or tough outer coverings that provide a framework of support  Protect soft body tissues  Provide protection from predators 24.1 Animal Characteristics Chapter 24

Support Introduction to Animals  Vertebrates  Endoskeletons  Protect internal organs  Provide support for the body  Provide an internal brace for muscles to pull against 24.1 Animal Characteristics Chapter 24

Movement Introduction to Animals  The evolution of nerve and muscle tissues enables animals to move in ways that are more complex and faster than organisms in other kingdoms. Chapter 24

Reproduction Introduction to Animals  Fertilization occurs when the sperm penetrates the egg to form a fertilized egg cell called the zygote.  Internal fertilization  External fertilization 24.1 Animal Characteristics Chapter 24

Introduction to Animals  Asexual reproduction means that a single parent produces offspring that are genetically identical to itself.  Budding  Fragmentation  Regeneration  Parthenogenesis 24.1 Animal Characteristics Chapter 24

Early Development Introduction to Animals  The zygote undergoes mitosis and a series of cell divisions to form new cells.  The cells continue to divide, forming a fluid- filled ball of cells called the blastula.  The blastula continues to undergo cell division as some cells move inward to form a gastrula Animal Characteristics Chapter 24

Introduction to Animals 24.1 Animal Characteristics Chapter 24 Cell Differentiation in Animal Development

Introduction to Animals Tissue Development  Endoderm  inner layer of cells in the gastrula  Ectoderm  outer layer of cells in the gastrula  Mesoderm  layer of cells between the endoderm and ectoderm 24.1 Animal Characteristics Chapter 24

Introduction to Animals 24.1 Animal Characteristics Chapter 24

24.2 Animal Body Plans Introduction to Animals Evolution of Animal Body Plans  Anatomical features in animals’ body plans mark the branching points on the evolutionary tree.  Relationships on this tree are inferred by studying similarities in embryological development and shared anatomical features. Chapter 24

Introduction to Animals 24.2 Animal Body Plans Chapter 24

Introduction to Animals Symmetry  Similarity or balance among body structures of organisms  Asymmetry  Radial symmetry  Bilateral symmetry 24.2 Animal Body Plans Chapter 24

Introduction to Animals Cephalization  The tendency to concentrate nervous tissue and sensory organs at the anterior end of the animal 24.2 Animal Body Plans Chapter 24

Introduction to Animals Body Cavities  Coelomates  Have a fluid- filled cavity with tissue formed from mesoderm that lines and encloses the organs in the coelom 24.2 Animal Body Plans Chapter 24

Introduction to Animals Body Cavities  Pseudocoelomates  Have a fluid-filled body cavity that develops between the mesoderm and the endoderm rather than developing entirely within the mesoderm 24.2 Animal Body Plans Chapter 24

Introduction to Animals Body Cavities  Acoelomates  Have solid bodies without a fluid-filled body cavity between the gut and the body wall 24.2 Animal Body Plans Chapter 24

 The mouth develops from the first opening in the gastrula. Introduction to Animals Development in Coelomate Animals  Protostomes  Deuterostomes  The anus develops from the first opening in the gastrula Animal Body Plans Chapter 24 Visualizing Protostomes and Deuterostomes

Introduction to Animals Segmentation  Segmented animals can be “put together” from a succession of similar parts.  Can survive damage to one segment  Movement is more effective 24.2 Animal Body Plans Chapter 24

Segmentation!

Michel Angelo’s David