Section 1 The Nature of Animals Chapter 32 Introduction to Animals Section 1 The Nature of Animals

Chapter 32 Objectives Identify 4 important characteristics of animals. List 2 kinds of tissues found only in animals. Explain how the first animals may have evolved from unicellular organisms. Identify four features found only in chordates.

Chapter 32 Characteristics Section 1 The Nature of Animals Chapter 32 Characteristics Animals are multicellular heterotrophic organisms that lack cell walls. Vertebrates have a backbone. Invertebrates do not have a backbone. 95 percent of all animal species alive today

Multicellular Organization Chapter 32 Multicellular Organization Each cell depends on the presence and functioning of other cells. specialization among cells tissue Organs Multicellularity and cell specialization have enabled organisms to adapt to many environments.

Evolutionary Relationships in the Animal Kingdom Chapter 32 Evolutionary Relationships in the Animal Kingdom Phylogenetic diagram represents hypothesis for the relationship among members of the animal kingdom based on rRNA analysis.

Evolutionary Relationships in the Animal Kingdom Chapter 32 Evolutionary Relationships in the Animal Kingdom Notice on this diagram the locations of similarities in body tissues, body symmetry and embryonic development.

Chapter 32 Heterotrophic Sexual Reproduction Characteristics of Animals Heterotrophic Sexual Reproduction gametes fuse and offspring are genetically different Movement Most animals move at some point within their life cycle As a result from the interrelationship of muscle tissue and nervous tissue, or neurons.

Origin and Classification Chapter 32 Origin and Classification The first animals may have evolved from colonial protists. Taxonomists have grouped animals into several phyla by comparing their: fossils body symmetry patterns of embryo development macromolecules, such as rRNA

Chapter 32 Classification Chordates All chordates have, at some stage in life: a notochord, flexible rod on the dorsal part of the body backbone a dorsal nerve cord, hollow cord brain and spinal cord a postanal tail pharyngeal pouches outpockets of anterior digestive tract gills for aquatic animals

Chapter 32 Patterns of symmetry Body Structure Patterns of symmetry Symmetry is a body arrangement in which parts that lie on opposite sides of an axis are identical. Types of symmetry are: no Symmetry (asymmetrical) radial symmetry bilateral symmetry cephalization concentration of sensory structures in the anterior region

Radial and Bilateral Symmetries Chapter 32 Radial and Bilateral Symmetries

Origins of Animal Tissues and Organs; Germ layers All animals have true tissues except sponges Chapter 32 Origins of Animal Tissues and Organs; Germ layers

The Animal Body: An Evolutionary Journey Chapter 32 Body Structure and Relatedness Biologists use similarities in body plans and patterns of development to help them classify animals and hypothesize about the evolutionary history of animals. The Animal Body: An Evolutionary Journey