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Arthropods

Arthropods. Chapter 28. Arthropod characteristics. Segmented bodies Tough exoskeleton made of chitin Multiple shapes and textures Jointed appendages: legs and antennae. Arthropod evolution. Modern arthropods have fewer body segments and more specialized appendages.

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Arthropods

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  1. Arthropods Chapter 28

  2. Arthropod characteristics • Segmented bodies • Tough exoskeleton made of chitin • Multiple shapes and textures • Jointed appendages: legs and antennae

  3. Arthropod evolution • Modern arthropods have fewer body segments and more specialized appendages. Fossil of a Trilobite, extinct class of Arthropod

  4. Fossil of Leanchoilia, Phylum Arthopoda www.burgess-shale.bc.ca/ gallery/gallery.htm

  5. Feeding • Herbivores, carnivores, omnivores, parasites, blood suckers, filter feeders, and detritovores • Variety of mouthparts: pincers, fangs, sickle-shaped jaws, feeding tubes stag beetle pincers

  6. Respiration • Most arthropods • Tracheal tubes: branching network of tubes that deliver and expel air through spiracles • Some arthropods (including spiders) • Book lungs: layers of respiratory tissue stacked like pages of a book

  7. Circulation • Open circulatory system: heart pumps blood to tissues, sinuses, and cavities but does not return to the heart directly

  8. Excretion • Malpighian tubules: saclike organs that extract wastes from blood and then add them to feces to move through the gut

  9. Chrysina quetzalcoatli is freed in Cusuco National Park, leaving a fecal trail National Geographic

  10. Response • Sensitive sensory organs (sight, smell, touch) • Well-developed nervous system • Brain • Ventral nerve cord • Ganglia: groups of nerve cells

  11. Movement • Flexor muscles • Extensor muscles • Muscle pulling against exoskeleton enables movement

  12. Reproduction • Terrestrial arthropods: internal fertilization • Male places sperm in female • Sperm sac that female picks up • Aquatic arthropods: internal or external fertilization

  13. Growth and development • Molting: period of shedding exoskeleton when outgrown • Glands secrete digestive enzymes to break down exoskeleton. • Glands secrete new exoskeleton. • Vulnerable stage Insect molting case left on tree bark

  14. Arthropod subphylums • Crustaceans • Spiders and their relatives • Insects and their relatives

  15. Crustacean characteristics • Two pairs of antennae • Two or three body sections • Mandibles: chewing mouthparts • Body plan: celphalothorax, abdomen, carapace • Barnacles have “lost” appendages. • Decapods have chelipeds and swimmerets. • Ex: shrimp, lobster, crayfish

  16. Tail Swimmerets Carapace First antenna Mandible Second antenna Cheliped The Anatomy of a Crayfish Section 28-2 Abdomen Cephalothorax Walking legs

  17. Subphylum Crustacea – hermit crab

  18. Subphylum Crustacea –crab

  19. Subphylum Crustacea – fire shrimp

  20. Chelicerate characteristics • Four pairs of walking legs • Chelicerae mouthparts: fangs that sting and pedipalps that grab prey • Two body sections: cephalothorax and abdomen • Classes: Merostomata (horseshoe crabs) and Arachnida (spiders, scorpions) • Spiders have spinnerets, silk glands.

  21. Pumpingstomach Heart Brain Intestine Ovary Eyes Malpighiantubules Poisongland Anus Pedipalp Spiracle Fanglikechelicera Spinnerets Bases ofwalking legs Silk glands Airflow The Anatomy of a Spider Section 28-2 Cephalothorax Abdomen Book Lung Figure 28–9 

  22. Subphylum Arachnida – black widow spider

  23. Scorpion

  24. Gum shoe spider web Theridae family National Geographic Photo by Darlyne A. Murawski

  25. Uniramia characteristics • Jaws • One pair of antennae • Unbranched appendages • Groups: centipedes, millipedes, insects

  26. Millipede

  27. Centipede

  28. Why insects are evolutionarily successful • Flight • Variety of stimuli responses • Differential feeding methods between young and adult • Different morphology between young and adult

  29. Insect characteristics • Compound eyes • Some with wings • Three part body plan • Three pairs of legs • Sensitive taste and smell receptors • Three appendages for mouth, including pair of mandibles

  30. Compound eye Brain Digestivetract Malpighian tubules Antennae Heart Reproductive organs Mouth Salivaryglands Legs Anus Ganglia Spiracles Trachealtubes Nervecord The Anatomy of a Grasshopper Section 28-1 Ventral View Tracheal tubes Spiracles Figure 28–4 

  31. Insect life cycle • Metamorphosis: process of changing shape and form from juvenile to adult stage • Incomplete: juvenile stage (nymphs) appear like adults, just smaller • Complete: juvenile stage (larvae) becomes pupa, final stage before becoming an adult

  32. Metamorphosis Section 28-3 Adult Eggs Adult Eggs IncompleteMetamorphosis CompleteMetamorphosis Larva Adult Nymph Nymph Immature Larva Nymph Adult Pupa Figure 28–18 

  33. Insects and humans • Although they can be a nuisance or pest, insects are significant to agriculture. • They facilitate flower pollination.

  34. Insect communication and societies • Chemical cues: pheromones • Visual cues: light, flight patterns • Some insects form societies where castes, groups of individuals, perform specific tasks.

  35. Polyphemus moth Pheromone chemical: (E,Z)-6,11-Hexadecadienyl acetate National Geographic Image  by Joseph Scheer

  36. Subphylum Insecta – lady bug

  37. Subphylum Insecta – bee moth

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