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Zoology

Zoology. Unit 1 Taxonomy Protozoa Early Embryonic Development Simple Metazoans. Chapter 10 - Taxonomy. 1. List the hierarchy of taxonomic ranks in the modern classification system 2. Compare & contrast concepts of species identification

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Zoology

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  1. Zoology Unit 1 Taxonomy Protozoa Early Embryonic Development Simple Metazoans

  2. Chapter 10 - Taxonomy 1. List the hierarchy of taxonomic ranks in the modern classification system 2. Compare & contrast concepts of species identification 3. Explain how taxonomic characters are used to infer evolutionary relationships 4. Define “clade”. Use shared and derived characters to construct cladograms 5. Identify characteristics that define the Animal Kingdom

  3. Taxonomic Ranks Taxonomic groupings are of human design, and are organized in a way to simplify our thinking about living organisms Early taxonomic systems recognized two Kingdoms, Plant and Animal As more varied organisms have been discovered, many do not neatly fit into either the Plant or Animal Kingdom

  4. Conflicts in Early Taxonomy Fungi have cell walls and are sessile, but cannot make their own food Many single celled organisms are capable of photosynthesis, but have well developed mechanisms for locomotion Cyanobacteria (formerly known as Cyanophyta) are photosynthetic, but lack organelles and a true nucleus

  5. Modern Taxonomy Taxonomic systems expanded from the early 2 kingdom approach to the recognition of 5 kingdoms: Monera (the bacteria), Protista, Fungi, Plantae, and Animalia Improvements in analytical techniques have uncovered significant differences in bacteria resulting in the recognition of 2 distinct types, Archaebacteria and Eubacteria

  6. A new level at the top: Domain • Modern trends in taxonomy emphasize ancestral relationships over convenience. The addition of Domain above the Kingdom level allows grouping of related Kingdoms. There are 3 recognized Domains: • Archaea – Includes the Kingdom Archaebacteria • Eubacteria – The “true Bacteria” • Eukarya – Eukaryotes: • Includes Kingdom Protista, Fungi, Plantae and Animalia

  7. Species • There are different approaches to the recognition of species. Each approach has advantages and disadvantages • Morphological Species Concept • Based on body form characteristics • Biological Species Concept • Based on the ability to interbreed • Evolutionary and Phylogenetic Species Concepts • Based on ancestral/evolutionary relationships

  8. Biological Species Concept Based on the ability to interbreed Some closely related species can interbreed, but their offspring are sterile (example: lion x tiger = liger) http://www.youtube.com/watch?v=CD6vpheUoPE

  9. Reflecting Ancestry in Taxonomy • Accurate interpretations of evolutionary relationships require a variety of evidence. The difficulty lies in determining which similarities are superficial and which reflect common ancestry • “Homology” reflects common ancestry • “Analogous” traits are evolved independently in separate lineages

  10. The Cladistic Approach Modern taxonomy is moving towards greater emphasis on common ancestry Cladistics is based on identifying an ancestral characteristic present in a lineage Progressively smaller groupings are formed as the result of “derived” characteristics A “clade” includes all descendants of a particular ancestral lineage

  11. Sample Cladogram

  12. Create a Cladogram

  13. Cladogram Sample #2

  14. Cladogram Sample #3

  15. Kingdom Animalia • Eukaryotic • Multicellular • Heterotrophic • No cell wall • No Chloroplasts

  16. Chapter 11 - Protozoa 6. Compare and contrast protozoans with animals 7. Describe means of locomotion employed by protozoans 8. Categorize major taxonomic groups of protozoans

  17. Protozoans = “first animals” • Animal-like protists. Unicellular, but: • Heterotrophic • Lack cell walls (usually) • Motile (usually) • http://www.youtube.com/watch?v=-zsdYOgTbOk&feature=related

  18. Modes of Protozoan Locomotion • Cilia • Relatively short and densely distributed over the surface of the cell

  19. Modes of Protozoan Locomotion • Flagellae • Longer and less numerous than cilia, but practically identical in internal structure

  20. Structure of Cilia & Flagellae • Internal structure consists largely of bundles of microtubules in a “9+2” arrangement • 9 pairs in a circular arrangement with 2 in the middle

  21. Cilia and Flagellae http://www.youtube.com/watch?v=QGAm6hMysTA

  22. Modes of Protozoan Locomotion • Pseudopodia • Literally “false feet” • Extensions of the cytoplasm used not only for movement but also for feeding

  23. Feeding and Movement of Amoebae http://www.youtube.com/watch?v=pvOz4V699gk http://www.youtube.com/watch?v=KeQ1c6_Md1Q http://www.youtube.com/watch?v=TOPMaNvGTvc http://www.youtube.com/watch?v=d_Bkg8euB5Y

  24. Modes of Protozoan Locomotion • Non-motile • All of these types are parasitic and rely on a “vector” for movement to a new host

  25. Traditional Protozoan Taxonomy Since motility is a trait generally associated with Animals, categorizing the protozoa by their locomotion was a logical approach: Flagellates – use flagellae Ciliates – use cilia Sarcodines – use pseudopodia Sporozoans – are nonmotile

  26. Chapter 12 – Simple Metazoans 9. Discuss the colonial flagellate hypothesis of metazoan origin 10. Identify distinguishing characteristics of the phylum mesozoa 11. Identify distinguishing characteristics of the phylum placozoa 12. Identify distinguishing characteristics of the phylum porifera 13. Discuss the fundamental anatomy of sponges 14. Relate variations in sponge canal systems to feeding efficiency 15. Categorize the classes of sponges

  27. Metazoans Metazoans, in contrast with Protozoans, are truly multicellular (with some differentiation of tissues) The most “primitive” of the metazoa are barely more than colonies of cells, but have some cells specialized for feeding, or reproduction, or locomotion

  28. Protozoan Ancestor to Animalia • 2 hypotheses have been advanced as to the protozoan ancestor to the animals: • Amoeboid ancestor • Flagellate ancestor • Cells resembling each of these protozoan forms exist in some form within the Animal kingdom • The more accepted hypothesis is the Flagellate ancestor hypothesis

  29. Flagellate Ancestor Hypothesis Cells called “Choanocytes” in sponges are identical in form and behavior to Choanoflagellateprotists, which may be free living or colonial

  30. Multicellularity Multicellular organisms differ from colonial organisms due to the specialization of cells and the division of labor that results. Groups of cells that are structurally and functionally specialized are “tissues” Tissues that combine together for related functions are “organs” Organs that perform a broad coordinated function form a “system”

  31. Differentiation & Development All animals share a common pattern of embryonic development (suggesting a common ancestry) Much of the phylogeny of Kingdom Animalia can be traced back to variations in early embryonic development Animal phyla generally considered “primitive” only go through a few stages of development, while the more “complex” phyla go through additional stages

  32. Early Embryonic Development • The zygote divides in two (“cleavage”), then 4, then 8, forming a raspberry shaped “morula” • Cleavage continues forming a hollow ball of cells called a “blastula”

  33. Cleavage Patterns and Differentiation • Note that there are 2 different patterns of cleavage, Radial and Spiral • Spiral cleavage results in greater early differentiation of cells

  34. Gastrulation • The blastula caves in on one end, forming an inner layer (endoderm) and an outer layer (ectoderm) • The resulting space (“Archenteron”) will form the digestive cavity

  35. Phylum Mesozoa • Mesozoa are basically an elongated Morula – They never reach the Blastula stage • Mesozoansare at the “cellular level” of organization. No true tissues exist • The inner layer of cells are specialized for reproduction • All known forms are parasitic

  36. Phylum Placozoa • The body form of placozoans is a flattened Blastula • Placozoa are also at the cellular level of organization • The “oral” surface is specialized for feeding and locomotion

  37. Phylum Porifera – The Sponges

  38. Phylum Porifera • The name Porifera is derived from many pores (ostia) that allow water to flow through the channels in the body wall, allowing the sponge to filter feed • The flow of water is driven by flagellated “choanocytes” lining the channels

  39. Sponge Anatomy

  40. Canal System Variations ASCONOID LEUCONOID SYCONOID

  41. Asconoid Sponges • The simplest canal system • Choanocytes line the spongeocoel

  42. Syconoid Sponges • The pouching of the spongeocoel into radial canals increases the surface area of contact between choanocytes and water flow

  43. Leuconoid Sponges • Incurrent canals direct water into specialized chambers lined with choanocytes • Excurrent canals direct water to the osculum to be expelled

  44. Spongin and Spicules

  45. Sponge Phylogeny • Phylum Porifera is divided into 3 classes • Class Calcarea • Calcium carbonate spicules • All 3 canal system types represented • Class Hexactinellidae • 6 rayed, siliceous spicules • Syconoid or Leuconoidcanal systems • Class Demospongiae • Siliceous spicules (not 6 rayed), spongin • Leuconoid canal systems

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