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What is an Animal? A multicellular organism of the kingdom Animalia that uses locomotion, metabolism, pronounced response to stimuli, and fixed bodily structure Characteristics of Animals • All animals have several characteristics in common. What are the four common characteristics of animals? – Eukaryotic – Multicellular – Heterotrophic – No cell wall What Do Animals Do to Survive? • • • • • • • Feed Respire Circulate Excrete Respond Move Reproduce Trends in Animal Evolution • Your survey of the animal kingdom will begin with simple forms and move through more complicated ones. Phylogenetic relationships: Trends in Animal Evolution Cell Specialization and Levels of Organization • Groups of specialized cells that work together form tissues. • Tissues join together to form organs. • Group of organs work together to form organ systems – EX: Circulatory system Cephalization • Concentration of sense organs and nerve cells at the front end or head of the body. Flatworm • Range in size from .2 inches to 50 feet! Animal Body Plans • What is symmetry? Arrangement of body parts on opposite sides of a plane or line Asymmetry Radial Symmetry Bilateral Symmetry What type of symmetry? • Radial What type of symmetry? • Bilateral What type of symmetry? • Asymmetrical What type of symmetry? • Radial Animal Body Plans • Acoelom – Without a body cavity Animal Body Plans • Pseudocoelom – Fluid-filled internal space that is in direct contact with the wall of the digestive tract. Animal Body Plans • Coelom – Fluid-filled body cavity completely lined by a layer of mesoderm cells and suspending internal organs Animal Body Plans How do these body plans develop? Early Development Development of Animal Body Plans • Cell Division – The zygote divides by mitosis and cell division to form two cells in a process called cleavage. – How important is this first cell division? • Problems can lead to defects in embryo Zygote Development of Animals: Gastrulation (a process of forming cell layers) • The zygote undergoes a series of divisions to form a blastula, which is a hollow ball of cells. Demo Phylums Porifera and Cnidaria only have two layers Protostome vs. deuterostome Mouth is formed from the blastopore Anus is formed from the blastopore Formation of a Coelom (body cavity): Neurulation • Body cavity – a fluid-filled space that lies between the digestive tract and the body wall. Gastrula Embryo Development