Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
29–1 Invertebrate Evolution Slide 1 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Origin of Invertebrates Origin of Invertebrates Invertebrate fossils, dating between 575 and 543 million years ago, were discovered in the Ediacara Hills of Australia and in Chengjiang, China. The Ediacaran fossils include some of the earliest and most primitive animals known. Slide 2 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Origin of Invertebrates The fossils: • were flat and plate shaped • were segmented • had bilateral symmetry • lived on the bottom of shallow seas • were made of soft tissues • absorbed nutrients from the surrounding water Slide 3 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Origin of Invertebrates Some of these animals may have had photosynthetic algae living within their bodies. Some may have been related to soft-bodied invertebrates. They were probably simple and had little internal specialization. Slide 4 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Origin of Invertebrates The animals of the Burgess Shale had many of the characteristics of modern day invertebrates including: • • • • • body symmetry segmentation a skeleton a front and a back end appendages adapted for many functions Slide 5 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Invertebrate Phylogeny Invertebrate Phylogeny Many features of modern invertebrates evolved during the Cambrian period such as: • tissues and organs • patterns of early development • body symmetry • cephalization • segmentation • formation of three germ layers and a coelom Copyright Pearson Prentice Hall Slide 6 of 34 29–1 Invertebrate Evolution Invertebrate Phylogeny Invertebrate Evolutionary Relationships Slide 7 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Invertebrate Phylogeny Roundworms Flatworms Cnidarians Sponges Unicellular ancestor Slide 8 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Invertebrate Phylogeny Slide 9 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Invertebrate Phylogeny Slide 10 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Invertebrate Phylogeny What are the major trends in invertebrate evolution? Slide 11 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Evolutionary Trends The appearance of each phylum in the fossil record represents the evolution of a successful and unique body plan. Features of this body plan typically change over time, leading to the formation of many new traits. Slide 12 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Slide 13 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Slide 14 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Specialized Cells, Tissues, and Organs As larger and more complex animals evolved, specialized cells joined together to form tissues, organs, and organ systems that work together to carry out complex functions. Flatworms have simple organs for digestion, excretion, response, and reproduction. More complex animals, such as mollusks and arthropods, have organ systems. Slide 15 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Body Symmetry All invertebrates, except sponges, exhibit some type of body symmetry. Slide 16 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Cnidarians and echinoderms exhibit radial symmetry where parts extend from the center of the body. Radial symmetry Planes of symmetry Copyright Pearson Prentice Hall Slide 17 of 34 29–1 Invertebrate Evolution Evolutionary Trends Worms, mollusks, and arthropods exhibit bilateral symmetry, or have mirror-image left and right sides. Bilateral symmetry Slide 18 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Cephalization Cephalization is the concentration of sense organs and nerve cells in the front of the body. Invertebrates with cephalization can respond to the environment in more sophisticated ways than can simpler invertebrates. Slide 19 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends In most worms and arthropods, nerve cells are arranged in structures called ganglia. In more complex invertebrates, nerve cells form an organ called a brain. Slide 20 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Segmentation Over the course of evolution, different segments in invertebrates have often become specialized for specific functions. Segmentation allows an animal to increase its size with minimal new genetic material. Slide 21 of 34 Copyright Pearson Prentice Hall 29–1 Invertebrate Evolution Evolutionary Trends Coelom Formation Flatworms are acoelomates. This means they have no coelom, or body cavity, that forms between the germ layers. Ectoderm Mesoderm Endoderm Digestive cavity Acoelomate Copyright Pearson Prentice Hall Slide 22 of 34 29–1 Invertebrate Evolution Evolutionary Trends Pseudocoelomates have a body cavity lined partially with mesoderm. Pseudocoelom Digestive tract Pseudocoelomate Copyright Pearson Prentice Hall Slide 23 of 34 29–1 Invertebrate Evolution Evolutionary Trends Most complex animal phyla have a true coelom that is lined completely with tissue derived from mesoderm. Coelom Digestive tract Coelomate Copyright Pearson Prentice Hall Slide 24 of 34 END OF SECTION