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Animals

Animals. What makes an animal? How can you tell if something is an animal or not? What are some examples of animals?. Evolution of Animals (intro). All animals are multicellular heterotrophic organisms that must take in preformed food. mulitcellular : made of more than one cell

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Animals

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  1. Introduction to Invertebrates

  2. Animals • What makes an animal? • How can you tell if something is an animal or not? • What are some examples of animals?

  3. Evolution of Animals (intro) • All animals are multicellular heterotrophic organisms that must take in preformed food. • mulitcellular: made of more than one cell • heterotrophic: take in preformed food from other organisms • food: complex organic molecules; often glucose related compounds

  4. Outline • Criteria for the Evolution of Animals • 1. Multicellularity • 2. True Tissues • 3. Bilateral Symmetry • 4. Body Cavities • 5. The Coelom • 6. Segmentation • 7. Development

  5. Evolution of Animals (intro) • All animals are multicellular heterotrophic organisms that must take in preformed food • Classification Criteria • Level of organization • Cellular, tissue, organ • Body Plan • Sac, tube-within-a-tube • Segmentation • Segmentation leads to specialization

  6. Evolution of Animals (intro) • Classification Criteria, cont • Symmetry • Radial - Two identical halves • Bilateral - Definite right and left halves • Type of Coelom • Acoelomate • Pseudocoelom • Coelom • Early Developmental Pattern • Protostome - First embryonic opening becomes the mouth • Dueterostome - Second embryonic opening becomes the mouth

  7. Animals:How does this picture demonstrate that an animal is involved?

  8. Traditional Phylogenetic Tree of Animals

  9. Animal? In order to be considered an animal, what must be true about this organism?

  10. Multicellularity • Sponges • Only level of animal to have cellular organization • Saclike bodies perforated by many pores • Beating of flagella produces water currents that flow through pores into central cavity and out osculum • Sessile filter feeders • Asexual reproduction by fragmentation or budding

  11. Simple Sponge Anatomy

  12. Porifera in the Animal Cladogram • Sponges • sitting at the bottom of the animal phylogeny • simplest of the existing animals and possibly one of the simplest of all time

  13. True Tissue Layers – Ctenophora & Cnidarians • Many animals have a total of three possible germ layers • Ectoderm – outside layer; skin or outer covering , brain and peripheral nerves • Endoderm – inside layer; gut track and some digestive tissues • Mesoderm – inner layer; muscles • phlyaCtenophora and Cnidaria develop only ectoderm and endoderm • Diploblasts – animals derived from only 2 embryonic layers • Radially symmetrical

  14. True Tissue Layers • phlyaCtenophora and Cnidaria develop only ectoderm and endoderm • So what is in the middle if these organisms (the first with true tissue layers) ? • What are Ctenophora called again?

  15. Types of Symmetry

  16. Comb Jellies - Ctenophora • Characteristics: • Small, transparent, and often luminescent • Most of body composed of mesoglea • Largest animals propelled by beating of cilia • Capture prey with tentacles

  17. Comb Jelly Compared to Cnidarian

  18. Cnidarians • Tubular animals that most often reside in shallow marine waters • Polyp and medusa body forms • Specialized stinging cells (cnidocytes) • Fluid-filled capsule, nematocyst • Two-layered body sac • Outer layer - Protective epidermis • Inner layer - Gastrovascular cavity • Nerve net found throughout body

  19. Cnidarian Diversity

  20. Hydra • Freshwater cnidarian • Small tubular poly body about one-quarter inch in length • Gastrovascular cavity is central cavity • Tentacles can respond to stimuli • Can reproduce sexually and asexually

  21. Anatomy of Hydra

  22. Obelia • A colony of polyps enclosed by a hard, chitinous covering. Chitin? • Feeding polyps • Extend beyond covering • Have nematocyst-bearing tentacles • Reproductive polyps • Budding of new polyps • Also has sexual reproduction (medusae) stage

  23. Obelia Life Cycle

  24. Ctenophora and Cnidarians • Where are we now? • How are cnidarians and ctenophora different from sponges? • What new “feature” do they posses that sponges did not have? • http://www.youtube.com/watch?v=bcmLxsJ5SAg&feature=related

  25. Bilateral Symmetry • New Characteristics • Bilateral Symmetry • animals have a “left and right” • one plane of symmetry • Cephalization • identifiable or obvious “head” end of the animal • having mouth and/or sensory organs at one end

  26. Bilateral Symmetry • Pseudocoelomates • Both phyla today will be considered pseudocoelomates • What is the difference between acoelomates, pseudocoelomates and coelomates (or eucoelomates?)

  27. Bilateral Symmetry • Coelomates(also known as eucoelomates — "true coelom") have a fluid filled body cavity called a coelom with a complete lining called peritoneumderived from mesoderm (one of the three primary tissue layers). • Pseudocoelomate have a pseudocoel (literally “false cavity”), which is a fully functional body cavity. Tissue derived from mesoderm only partly lines the fluid filled body cavity of these animals. Thus, although organs are held in place loosely, they are not as well organized as in a coelomate. • Acoelomateanimals, like flatworms, have no body cavity at all. Organs have direct contact with the epithelium. Semi-solid mesodermal tissues between the gut and body wall hold their organs in place.

  28. Bilateral Symmetry • Flatworms (phylum Platyhelminthes) • Majority are parasitic • Organ-level organization • No specialized circulatory or respiratory structures • Have undergone cephalization • Ladder-type nervous system • Ribbon worms (phylum Nemertea) • Have distinctive proboscis • Have a complete gut track

  29. Belong to the phylum platyhelminthes. (Plat = flat) There are three classes: Turbellaria Trematoda Cestoda Flatworms

  30. They are acoelomates (they don’t have body cavities) They have bilateral symmetry Show cephalization Respiration through skin Single opening to digestive tract (pharynx) Characteristics of Flatworms

  31. Free-living Flatworms • Planarians (genus Dugesia) • Live in freshwater habitats • Head is bluntly arrow shaped • Auricles function as sense organs • Two light-sensitive eye spots • Three kinds of muscle layers: • Outer circular layer • Inner longitudinal layer • Diagonal layer

  32. Planarian Anatomy

  33. Planarians • Planarians, cont. • Excretory organ functions in osmotic regulation and water excretion • Can reproduce asexually • Hermaphroditic • Practice cross-fertilization

  34. Parasitic Flatworms • Parasitic flatworms are flukes (trematodes) and tapeworms (cestodes) • Well-developed nerves and gastrovascular cavity are unnecessary • Flukes • Reproductive system well developed • Usually hermaphroditic

  35. Life Cycle of Schistosomiasis

  36. Parasitic Flatworms • Tapeworms • Have anterior region with modifications for attachment to intestinal wall of host • Behind head region, scolex, a long series of proglottids are found • Segments each containing a full set of both male and female sex organs • Complicated life cycles

  37. Life Cycle of a Tapeworm, Taenia

  38. Are parasitic flukes Have suckers on both ends of the body Can live inside or outside of host Not much cephalization Class Trematoda

  39. Nervous and excretory systems like turbellarians Hermaphrodites Have complex life cycles Class Trematoda

  40. Parasitic Tapeworms Long, ribbon-like bodies Absorbs nutrients from host Hermaphrodites Class Cestoda

  41. TapewormAnatomy

  42. Ribbon Worm, Lineus

  43. The nemerteans (ribbon worms) are long, marine predatory worms and there are about 1000 species known. Unlike members of the Platyhelminthes nemerteans have a complete gut with a mouth and anus and a true circulatory system Phylum Nemertea (Rhynchocoela) Ribbonworms

  44. Prey is captured using a long muscular proboscis armed with a barb called a stylet.. The proboscis lies in an interior cavity called the rhynchocoel and muscular pressure on fluid in the rhynchocoel causes the proboscis to be quickly everted. The prey is wrapped in the sticky, slime-covered, proboscis and stabbed repeatedly with the stylet. Neurotoxins in the slime incapacitate the prey. Phylum Nemertea (Rhynchocoela) Ribbonworms

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