Lecture 5-new - Lecture 5 Animal Evolution – The...

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Unformatted text preview: Lecture 5 Animal Evolution – The Invertebrates Learning Objectives  To describe the characteristics and definitions of animals o To gain knowledge regarding the origin of animals o To describe the various features of the different groups of invertebrates. Learning Outcomes  Upon successful completion of the lecture, students will be able to: › Define and explain the characteristics of all animals. › Relate the evolution of ancestor cells that evolved to form the animal cells and eventually the animal itself › Explain the characteristics of the various invertebrates in terms of their body plans, eating habits, habitats and unique features Define Animals.  Multicelled: o cells having diploid chromosomes. e Aerobic heterotrophs o Undergo Sexual/Asexual reproduction o Lack backbone o Lack cell wall o Most move actively o Most form tissues Animal Tissues  Cells interact with each other form the epithelium & connective tissues o Epithelium – o Connective tissues – o Primary tissues develop into all tissues and organs. o These primary tissues are: › Ectoderm › Endoderm › Mesoderm Primary Tissues  Ectoderm ; lines the body surface o Endoderm ; layers the inner gut lining o Mesoderm ; forms in between these two, sources of muscles, forms many organs. o Radial animals have all the tissues except mesoderm o Bilateral animals have all three tissues Body Size of Animals Similarities & differences of animal body plans can be compared with regards to these features: › body symmetry & cephalization › type of gut › body cavities › segmentation. Bilateral c Radial Body parts arranged regularly around a central axis. o Body plan adapted to intercept food coming from any direction. o These animals live in water Right half & left half are mirror images of each other. o Have anterior, posterior, dorsal & ventral. o Evolved from forward-creeping species. o Forward end encounter food & other stimuli. o Subsequently cephalization occurred??? o Bilateral body plans & cephalization coevolved Gut is a digestive sac or tube with one opening or two openings o Can be divided into two: o Saclike c Tubular ones Sac-like gut: › is an incomplete digestive system › first to evolve o Tubular gut: › is a complete digestive system › starts at mouth and ends with anus Meaning space o Exist in between the gut & body wall of most bilateral animal o Has unique tissue lining; peritoneum. o Peritoneum; encloses organs in the coelom. Type of body cavity found in most bilateral animals o Key component in the larger & more complex animals. o Less complex invertebrates do not have body cavity (coelom), tissues fill the regions between gut and body wall....
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This note was uploaded on 06/21/2009 for the course BIO 150 taught by Professor Kore during the Spring '08 term at Abraham Baldwin Agricultural College.

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Lecture 5-new - Lecture 5 Animal Evolution – The...

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