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Animal Evolution –The Invertebrates

Animal Evolution –The Invertebrates. Chapter 25 Part 3. 25.11 Roundworms— Unsegmented Worms That Molt. Roundworms (phylum Nematoda) are unsegmented, pseudocoelomate worms with a secreted cuticle that is molted Most are decomposers, some are parasites

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Animal Evolution –The Invertebrates

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  1. Animal Evolution –The Invertebrates Chapter 25 Part 3

  2. 25.11 Roundworms— Unsegmented Worms That Molt • Roundworms (phylum Nematoda) are unsegmented, pseudocoelomate worms with a secreted cuticle that is molted • Most are decomposers, some are parasites • Parasitic roundworms include Trichinella, Ascaris, hookworms, Wuchereria, and pinworms

  3. Roundworm Body Plan

  4. pharynx intestine eggs in uterus gonad false coelom (unlined body cavity) muscular body wall anus Fig. 25-29a, p. 420

  5. Animation: Roundworm body plan

  6. Roundworms

  7. 25.12 Arthropods—Animals With Jointed Legs • Arthropods (phylum Arthropoda) are the most diverse animal phylum – with more than a million species • Trilobites are an extinct group • Modern arthropods include horseshoe crabs, spiders, ticks, crabs, lobsters, centipedes, and insects

  8. Living Arthropod Subgroups

  9. Key Arthropod Adaptations • A hardened exoskeleton (cuticle) • Hormones control molting • Jointed appendages for movement • Some legs are modified for special tasks • Highly modified segments • Example: wings

  10. Key Arthropod Adaptations • Sensory specializations • Compound eyes • Antennae that detect touch and chemicals • Specialized developmental stages • Body plans may change by metamorphosis • Example: Caterpillar and butterfly

  11. Key Arthropod Adaptations

  12. Fig. 25-31a, p. 421

  13. Fig. 25-31b, p. 421

  14. Fig. 25-31c, p. 421

  15. Fig. 25-31d, p. 421

  16. 25.13 Chelicerates—Spiders and Their Relatives • Chelicerates are arthropods without antennae • Marine chelicerates include the oldest living arthropod lineage (horseshoe crabs) • All land chelicerates are arachnids, including spiders, scorpions, ticks, and mites

  17. Chelicerates

  18. telson Fig. 25-32a, p. 422

  19. telson (with stinger) pedipalp cephalothorax abdomen Fig. 25-32b, p. 422

  20. Fig. 25-32c, p. 422

  21. Fig. 25-32d, p. 422

  22. Fig. 25-32e, p. 422

  23. Fig. 25-32f, p. 422

  24. Chelicerates: The Spiders • Spiders bite with fanglike chelicerae that deliver venom from poison glands • Paired spinners in the abdomen eject silk • Open circulatory system mingles blood with tissue fluids; Malpighian tubules move excess water and wastes to gut for disposal

  25. Body Plan of a Spider

  26. digestive gland Malpighian tubules eye brain heart poison gland anus pedipalp chelicera spinners mouth book lung ovary sperm receptacle silk gland Fig. 25-33, p. 422

  27. 25.14 The Mostly Marine Crustaceans • Crustaceans are mostly marine arthropods with two pairs of antennae • Small crustaceans include krill, copepods, and barnacles • Decapod crustaceans include lobsters, crayfish, crabs and shrimps

  28. Crustaceans

  29. Fig. 25-34a, p. 423

  30. Fig. 25-34b, p. 423

  31. Fig. 25-34c, p. 423

  32. Fig. 25-34d, p. 423

  33. Body Plan of a Lobster

  34. abdomen segments cephalothorax (fused segments) eyes (two) antennae (two pairs) food-handling appendages (three pairs) swimmerets tail fan first leg walking legs (five pairs) Fig. 25-35, p. 423

  35. Crab Life Cycle

  36. egg adult female juvenile larva Fig. 25-36, p. 423

  37. egg adult female juvenile larva Stepped Art Fig. 25-36, p. 423

  38. Animation: Crab life cycle

  39. 25.15 Myriapods—Lots of Legs • Myriapods (“many feet”) are arthropods with two antennae and many body segments • Centipedes are predators • Millipedes are scavengers

  40. Myriapods • Centipede and millipede

  41. 25.16 The Insects • Insects have a three-part body plan • The head has compound eyes, a pair of antennae, and specialized mouthparts • The thorax has three pairs of legs; some lineages have wings • Malpighian tubules in the abdomen eliminate wastes and save water

  42. Insect Body Plan: Bedbug

  43. abdomen thorax with six legs head with two eyes, and two antennae Fig. 25-38, p. 424

  44. Specialized Mouthparts

  45. liplike labrum antenna compound eye mandible maxilla maxilla palps liplike labrum a c b labium d Fig. 25-39, p. 425

  46. Animation: Insect head parts

  47. Insects • Arthropods are the most successful animals, and insects are the most successful arthropods • Insects are adapted to life on land; a system of tracheal tubes delivers air to their tissues • Development may be direct, or through incomplete or complete metamorphosis

  48. Insect Development

  49. a Direct development: Growth in size between molts but no change in body form egg young adult b Incomplete metamorphosis: gradual change with each molt until the nymph becomes adult egg nymphs adult c Complete metamorphosis: larvae grow, then molt into a pupa, which is remodeled into the adult form egg larvae pupa adult Fig. 25-40, p. 425

  50. 25.17 Insect Diversity and Importance • It would be hard to overestimate the importance of insects, for either good or ill • Insects help provide us with food crops, are food for animals, and help dispose of wastes • The four most diverse groups of insects all include pollinators of flowering plants • A few insects eat our crops or carry pathogens

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