Survey of the Animal Kingdom – Unit III - Chapters 29, 30, and 31

1. Survey of the Animal Kingdom – Unit III - Chapters 29, 30, and 31 • Invertebrates – Chapters 29 & 30 • Vertebrates – Chapter 31 • * Approximately one million animals have been identified and classified.

2. Introduction to Invertebrates

3. Outline • Evolution of Animals • Multicellularity • Sponges • True Tissues • Cnidarians and Comb Jellies • Hydra • Obelia • Bilateral Symmetry • Flatworms • Roundworms • Body Cavities • Acoelomates • Psuedocoelomates • Eucoelomates

4. Animals Animals:Multicellular, Heterotrophic Eukaryotes

5. Evolution of Animals • All animals are multicellular heterotrophic organisms that must take in (ingest) preformed food • Classification Criteria: • Level of organization • Cellular – no true tissues, like sponges • Tissue – two germ layers, like jellyfishes; diploblastic with ectoderm and endoderm • Organ – three germ layers, like octopuses; triploblastic, also the mesoderm

6. Classification Criteria, contd. • Body Plan • Sac plan – like jelly fishes and tapeworms; have incomplete digestive systems – only one opening as an entrance for food and exit for undigested material • Tube-within-a-tube plan – like roundworms and alligators; have complete gastrointestinal tracts – have two openings

7. Classification Criteria, contd. • Segmentation • Repetition of body parts along length of the body • Segmentation leads to specialization of parts cause the various segments can become differentiated for different purposes • EXAMPLES SEGMENTATION: • Earthworms – annelids • Grasshoppers – arthropods • Hawks - chordates

8. Classification Criteria, contd. • Symmetry • Radial - cylindrical in shape, e.g. sea stars - Two identical halves • Bilateral - Definite right and left halves (longitudinal section) • Asymmetrical – some sponges, no particular body shape

9. Classification Criteria, contd. • Type of Coelom - a true body cavity found in many animals that contains internal organs • Acoelomate – no body cavity; tapeworms have mesoderm but no coelom • Pseudocoelomates - coelom incompletely lined by mesoderm; roundworms, where a layer of mesoderm exists beneath the body wall, but not around the gut. • Coelomates - coelom completely lined with mesoderm • Either protostomes or deuterostomes

10. Classification Criteria, contd. • Early Developmental Pattern • Protostome - First embryonic opening (the blastopore) becomes the mouth. • e.g. spiders • Dueterostome - First embryonic opening (the blastopore) is associated with the anus; the second embryonic opening is associated with the mouth. • e.g. monkeys

11. Classification Criteria, contd. • Molecular Data • The more closely related two organisms are the more nucleotide (rRNA) sequences they will have in common.

12. 1. Digestive systems – complete and incomplete A. nutritional strategies 1. herbivore 2. carnivore/ predator 3. omnivore 4. scavenger 5. parasite 6. filter feeder 2. Circulatory systems – open and closed 3. Respiratory systems – diffusion, gills, lungs, spiracles and trachea 4. Excretory systems – protonephridia, nephridia, kidneys Comparative Animal Anatomy

13. 5. Skeletal system – Endoskeleton – inner skeleton Exoskeleton – outer skeleton 6. Muscular system – longitudinal, circular, oblique muscle fibers 7. Nervous systems – nerve net, ganglia, central nervous system, ventral and dorsal nerve cords 8. Reproduction A. sexual and asexual B. separate sexes and hermaphrodites Comparative Animal Anatomy, contd.

14. Traditional Phylogenetic Tree of Animals 12 Phyla Anatomical & embryological data

15. Evolutionary Tree (Ribbonworms) (Rotifers) (Ctenophora – comb jellies)

16. Multicellularity • Sponges – 5000 species • Only level of animal to have cellular organization; lack true tissues • Mostly marine but some freshwater forms • 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

17. Sponges continued • Unique Features - asymmetrical, only two germ layers present, no organs or organ systems, simplest animals • 1. choanocyte - "collar cells", function in feeding and reproduction • 2. amoebocyte – wandering amoebalike cells that function in digestion and transfer of nutrients from cell to cell, spicule-formation, and reproduction • 3. spicules - skeletal elements of a sponge; may be composed of calcium carbonate, silicates, or spongin • Digestion and Nutrition - filter-feeding organisms; collar cells and amoebocytes cooperate with digestive process • Locomotion - sessile except during larval stages • Defense - spicules • Reproduction - sexual or asexual by budding or fragmentation

18. Simple Sponge Anatomy

19. True Tissue Layers • Total of three possible germ layers - embryonic tissue from which all other animal tissues arise. • Ectoderm – outermost primary tissue layer of an animal embryo; gives rise to the nervous system and outer layer – epidermis and derivatives • Mesoderm – middle primary layer of animal embryo; gives rise to musculoskeletal, some internal organs, and connective tissues. • Endoderm – innermost primary tissue layer of embryo; gives rise to linings of digestive and respiratory tracts, and associated structures. • Phlya Ctenophora and Cnidaria develop only ectoderm and endoderm • Diploblasts • Radially symmetrical

20. Ctenophora - Comb Jellies • Small, transparent, and often bioluminescent • 90 species, mostly free swimming marine • Most of body composed of jellylike mesoglea • Largest animals propelled by beating of cilia • Capture prey with tentacles

21. Comb Jelly Compared to Cnidarian Comb jelly Cnidarian, medusan form

22. Cnidarians • Tubular animals that most often reside in shallow marine waters – 10,000 species • Polyp and medusa body forms - many species possess two unique stages during their life cycles; the stalk-like polyp and the free-swimming bell-shaped medusa • Specialized stinging cells (cnidocytes) • Fluid-filled capsule, nematocyst – threads that trap or paralyze prey • Use tentacles and cnidocytes to ingest food into the gastrovascular cavity; no true digestive system • Layered body sac • Outer layer - Protective epidermis (from ectoderm) • Inner layer - Gastrovascular cavity (from endoderm) • Nerve net found throughout body

23. Cnidarian Diversity

24. 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 (budding) • Capable of limited movement

25. Anatomy of Hydra

26. Obelia • Brackish water and marine colonial hydrozoan • A colony of polyps enclosed by a hard, chitinous covering • Feeding polyps • Extend beyond covering • Have nematocyst-bearing tentacles • Reproductive polyps • Asexual budding of new polyps from sessile polyp • Also has sexual reproduction (medusae) stage

27. Obelia Life Cycle

28. Bilateral Symmetry • Ribbon worms (phylum Nemertea) • Have distinctive proboscis for feeding, burrowing, defense and locomotion; bottom dwelling marine worms

29. Ribbon Worm, Lineus

30. Flatworms (Phylum Platyhelminthes) flattened, bilateral body plan; acoelomates epidermis, endoderm and mesoderm; no coelom Majority are parasitic; some free living; 20,000 species Organ-level organization Digestive system incomplete; excretory system No specialized circulatory or respiratory structures Have undergone cephalization Ladder-type nervous system Bilateral Symmetry

31. Free-living Flatworms - Turbellarians • 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 • Sexual reproduction - Hermaphroditic • Practice cross-fertilization; eggs hatch as tiny worms

34. Parasitic Flatworms • Parasitic flatworms are flukes (trematodes) and tapeworms (cestodes) • Well-developed nerves and gastrovascular cavity are unnecessary • Hooks and/or suckers for attachment to host • Flukes • Reproductive system well developed • Usually hermaphroditic

35. Life Cycle of Schistosomiasis Blood fluke, Schistoma

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 (reproductive units) 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. Pseudocoelom • Pseudocoelom: • A “false” body cavity that is incompletely lined by mesoderm • Provides a space for internal organs and can serve as hydrostatic skeleton • Roundworms (phylum Nematoda) • Rounded body, bilateral symmetry, pseudocoelomates • Non-segmented, generally colorless worms • free-living and parasitic lifestyles illustrated, complete digestive tract with mouth and anus • Several parasitic roundworms infect humans

39. Roundworm Anatomy

40. Parasitic Roundworms • Ascaris – Intestinal roundworm • Trachinella - Trichinosis • Dirofilaria - Heartworms • Wuchereria – Elephantiasis – swelling in lyphatic vessels • Pinworms – most common nematode parasite in U.S.

41. Filarial Worm

42. Rotifers • Rotifers (phylum Rotifera) • 2000 species; mainly fresh water forms • Named for crown of cilia (corona) resembling a rotating wheel • Serves as both as an organ of locomotion and aids direction of food to mouth

43. Rotifer

44. Review • Evolution of Animals • Multicellularity • Sponges • True Tissues • Cnidarians and Comb Jellies • Hydra • Obelia • Bilateral Symmetry • Flatworms • Roundworms • Body Cavities • Acoelomates • Psuedocoelomates • Eucoelomates

45. Introduction to Invertebrates