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Chapter 33

Chapter 33. Invertebrates. LE 33-2. Cnidaria. Echinodermata. Chordata. Porifera. Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida). Deuterostomia. Bilateria. Eumetazoa. Ancestral colonial choanoflagellate. LE 33-3a. A jelly. A sponge. 0.5 mm. 250 µm.

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Chapter 33

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  1. Chapter 33 Invertebrates

  2. LE 33-2 Cnidaria Echinodermata Chordata Porifera Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Deuterostomia Bilateria Eumetazoa Ancestral colonial choanoflagellate

  3. LE 33-3a A jelly A sponge 0.5 mm 250 µm A placozoan (LM) A kinorhynch (LM) A rotifer (LM) A marine flatworm Ectoprocts Phoronids

  4. LE 33-3b A ribbon worm A brachiopod 5 mm A ctenophore, or comb jelly An acanthocephalan An octopus A marine annelid 50 µm A priapulan A loriciferan (LM)

  5. LE 33-3c A roundworm A scorpion (an arachid) 100 µm 100 µm Tardigrades (colorized SEM) A cycliophoran (colorized SEM) An acorn worm An onychophoran A sea urchin A tunicate

  6. Sponges • Characteristics • Suspension feeders • Hermaphrodites • Sessile • Structure • Spongocoel • Osculum • Choanocytes • Mesohyl • Amoebocytes

  7. LE 33-4 Food particles in mucus Flagellum Choanocyte Choanocytes Collar Osculum Azure vase sponge (Callyspongia plicifera) Spongocoel Phagocytosis of food particles Amoebocyte Porocytes Spicules Epidermis Water flow Amoebocyte Mesohyl

  8. Cnidarians • Characteristics • Radial symmetry • Gastrovascular cavity • Cnidocytes, cnidae, and nematocysts • Carnivores • Body plan • Polyps • Medusa

  9. LE 33-5 Mouth/anus Tentacle Polyp Medusa Gastrovascular cavity Gastrodermis Mesoglea Body stalk Epidermis Tentacle Mouth/anus

  10. LE 33-6 Prey Tentacle “Trigger” Discharge of thread Nematocyst Coiled thread Cnidocyte

  11. Four classes of Cbidaria • Hydrozoans • Both polyp and medusa stages • Scyphozoans • Poly stage reduced, free-swimming • Cubozoans • Box-shaped medusae, complex eyes • Anthozoans • No medusa stage, most sessile

  12. Table 33-1

  13. LE 33-7 Scyphozoans (jellies) Cubozoan (sea wasp) Anthozoan (sea anemone) Hydrozoans

  14. Reproductive polyp Feeding polyp LE 33-8–3 Medusa bud MEIOSIS Gonad Medusa Sperm Egg SEXUAL REPRODUCTION ASEXUAL REPRODUCTION (BUDDING) Portion of a colony of polyps FERTILIZATION Zygote Developing polyp Mature polyp Planula (larva) Key Haploid (n) 1 mm Diploid (2n)

  15. Clade Bilateria (Bilateral symmetry)Phyla: • Platyhelminthes (Flatworms) • Live in marine, freshwater and damp terrestrial habitats • Acoelomates, triplobastic development • Flat shape - adaptation • Rotifera • Live in marine, freshwater and damp soil • Alimentary canal replaces gastrovascular cavity • Pseudocoelomates • Parthenogenesis

  16. Table 33-2

  17. Pharynx LE 33-10 Gastrovascular cavity Eyespots Ganglia Ventral nerve cords

  18. LE 33-12 Proglottids with reproductive structures 200 µm Scolex Hooks Sucker

  19. LE 33-13 0.1 mm

  20. More Phyla of Bilateria • Lophophorates • Ectoprocta, Phoronida, and Brachiopoda • Have lophphore • U-shaped alimentary canal • No distinct head • Nemertea • Ribbon worms • Have alimentary canal (unlike flatworms) • Closed circulatory system (unlike flatworms)

  21. LE 33-14 Lophophore Lophophore Ectoprocts Phoronids Brachiopods

  22. Figure 33-15

  23. Molluscs • Snails, slugs, oysters, clams, octopi, squid • Most marine • Soft-bodied, hard shell (most) • Similar body plan • Muscular foot • Visceral mass • Mantle • Many also have mantle cavity, radula • Life cycle – most have separate sexes, larval stage (trochophore)

  24. Visceral mass LE 33-16 Coelom Heart Intestine Nephridium Gonads Mantle Stomach Radula Mantle cavity Shell Mouth Radula Anus Gill Mouth Nerve cords Foot Esophagus

  25. Figure 33-17

  26. A land snail LE 33-18 A sea slug. Nudibranchs, or sea slugs, lost their shell during their evolution.

  27. Stomach Intestine Mantle cavity LE 33-19 Anus Mouth

  28. Figure 33-20

  29. Coelom Hinge area Mantle Gut Heart Adductor muscle LE 33-21 Shell Anus Mouth Excurrent siphon Palp Water flow Foot Incurrent siphon Mantle cavity Gill

  30. LE 33-22 Squids are speedy carnivores with beaklike jaws and well-developed eyes. Chambered nautiluses are the only living cephalopods with an external shell. Octopuses are considered among the most intelligent invertebrates.

  31. Annelids – Segmented worms

  32. Cuticle Coelom Epidermis Septum (partition between segments) Circular muscle LE 33-23 Longitudinal muscle Metanephridium Anus Dorsal vessel Chaetae Intestine Ventral vessel Nerve cords Nephrostome Metanephridium Clitellum Esophagus Crop Pharynx Intestine Giant Australian earthworm Cerebral ganglia Gizzard Mouth Ventral nerve cords with segmental ganglia Subpharyngeal ganglion Circulatory system

  33. Nematodes • Roundworms • No segmented body, cylindrical bodies • Pseudocoelomates • Have a cuticle • Mostly sexual reproduction • Examples: • C. elegans • Trichinella spiralis

  34. LE 33-26 25 µm

  35. Muscle tissue Encysted juveniles 50 µm LE 33-27

  36. Arthropods • General characteristics • Segmented • Coelomates • Exoskeletons • Open circulatory systems • Specialized organs for gas exchange

  37. Table 33-5

  38. Cephalothorax Abdomen LE 33-29 Thorax Head Antennae (sensory reception) Swimming appendages (two sets located under abdomen Walking legs Pincer (defense) Mouthparts (feeding)

  39. Figure 33-30

  40. LE 33-31 50 µm Scorpions have pedipalps that are pincers specialized for defense and the capture of food. The tip of the tail bears a poisonous stinger. Dust mites are ubiquitous scavengers in human dwellings but are harmless except to those people who are allergic to them (colorized SEM). Web-building spiders are generally most active during the daytime.

  41. Stomach Intestine LE 33-32 Brain Heart Digestive gland Eyes Ovary Poison gland Anus Book lung Gonopore (exit for eggs) Spinnerets Pedipalp Chelicera Sperm receptacle Silk gland

  42. Figure 33-33

  43. Figure 33-34

  44. LE 33-35 Thorax Abdomen Head Compound eye Antennae Dorsal artery Crop Cerebral ganglion Heart Anus Vagina Malpighian tubules Ovary Tracheal tubes Mouthparts Nerve cords

  45. LE 33-36 Larva (caterpillar) Pupa Pupa Emerging adult Adult

  46. LE 33-37aA APPROXIMATE NUMBER OF SPECIES MAIN CHARACTERISTICS EXAMPLES ORDER Blattodea 4,000 Cockroaches have a dorsoventrally flattened body, with legs modified for rapid running. Forewings, when present, are leathery, whereas hind wings are fanlike. Fewer than 40 cockroach species live in houses; the rest exploit habitats ranging from tropical forest floors to caves and deserts. German cockroach

  47. LE 33-37bA APPROXIMATE NUMBER OF SPECIES MAIN CHARACTERISTICS EXAMPLES ORDER Beetles comprise the most species-rich order of insects. They have two pairs of wings, one of which is thick and leathery, the other membranous. They have an armored exoskeleton and mouthparts adapted for biting and chewing. Beetles undergo complete metamorphosis. Coleoptera 350,000 Japanese beetle

  48. LE 33-37cA APPROXIMATE NUMBER OF SPECIES MAIN CHARACTERISTICS EXAMPLES ORDER Earwigs are generally nocturnal scavengers. While some species are wingless, others have two pairs of wings, one of which is thick and leathery, the other membranous. Earwigs have biting mouthparts and large posterior pincers. They undergo incomplete metamorphosis. Dermaptera 1,200 Earwig

  49. LE 33-37dA APPROXIMATE NUMBER OF SPECIES MAIN CHARACTERISTICS EXAMPLES ORDER Dipterans have one pair of wings; the second pair has become modified into balancing organs called halteres. Their head is large and mobile; their mouthparts are adapted for sucking, piercing, or lapping. Dipterans undergo complete metamorphosis. Flies and mosquitoes are among the best-known dipterans, which live as scavengers, predetors, and parasites. Diptera 151,000 Horsefly

  50. LE 33-37eA APPROXIMATE NUMBER OF SPECIES MAIN CHARACTERISTICS EXAMPLES ORDER Hemipterans are so-called “true bugs,” including bed bugs, assassin bugs, and chinch bugs. (Insects in other orders are sometimes erroneously called bugs.) Hemipterans have two pairs of wings, one pair partly leathery, the other membranous. They have piercing or sucking mouthparts and undergo incomplete metamorphosis. Hemiptera 85,000 Leaf- footed bug

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