Friday, October 23, 2020

Animal Kingdom - Notes | Class 11 | Part 8: Arthropoda

4. ANIMAL KINGDOM

PHYLUM ARTHROPODA (JOINT-LEGGED ANIMALS): GENERAL CHARACTERS

Arthropoda is the largest phylum. Over two-thirds of all named species are arthropods.
  1. Grades of organization:
    • Organ system.
  2. Symmetry:
    • Bilateral symmetry.
  3. Germ layers:
    • Triploblastic.
  4. Coelom:
    • Coelomate.
  5. Habit and habitat:       
    • Cosmopolitan.
  6. Digestive system:          
    • Complete.
  7. Respiratory system:
    • Gills/ book gills/ trachea/book lungs.
  8. Circulatory system:
    • Open type.
  9. Reproduction:
    • Mostly dioecious.
    • Usually internal fertilization.
    • Mostly oviparous.
    • Development is direct or indirect.
  10. Unique features:
    • Jointed appendages.
    • Body has 3 regions: head, thorax & abdomen.
    • Body is covered by chitinous cuticle (exoskeleton).
    • Excretion by Malpighian tubules.
    • Sensory organs are antennae, compound & simple eyes, statocysts (balance organs).
  11. Examples:
    • Spider, Scorpion, Crab, Prawn, Insects etc.
    • Economically important insects: Apis, Bombyx, Laccifer.
    • Vectors: Mosquitoes (Anopheles, Culex & Aedes), Housefly etc.
    • Gregarious pest: Locusta.
    • Living fossil: Limulus (King crab).

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