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spider
Table of Contents
  • Introduction
  • General features
    • Size range
    • Distribution
    • Importance
  • Form and function
    • External features
    • Internal features
      • Nervous system and senses
      • Digestion and excretion
      • Respiration
      • Circulation
      • Reproductive system
    • Specialized features
      • Venom
      • Silk
  • Natural history
    • Reproduction and life cycle
      • Courtship
      • Mating
      • Eggs and egg sacs
      • Maturation
    • Feeding behaviour
      • Stalking prey
      • Spider webs
  • Classification
    • Distinguishing taxonomic features
    • Annotated classification
References & Edit History Quick Facts & Related Topics
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Animal Factoids
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Science Bugs, Mollusks & Other Invertebrates Arachnids

Internal features

in spider in Form and function
Also known as: Araneae, Araneida
Written by
Lorna R. Levi
Coauthor of A Guide to Spiders and Their Kin; cotranslator and coeditor of Invertebrate Zoology by A. Kaestner.
Lorna R. Levi,
Herbert W. Levi
Emeritus Professor of Biology, Harvard University; Curator of Arachnology, Museum of Comparative Zoology, 1966–91. Coauthor of A Guide to Spiders and Their Kin; cotranslator and coeditor of Invertebrate...
Herbert W. Levi•All
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Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.
The Editors of Encyclopaedia Britannica
Last Updated: Apr 27, 2025 • Article History
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News •

New Caterpillar Found in Hawaii Wears Dead Bugs and Lives With Spiders • Apr. 25, 2025, 4:31 AM ET (Gizmodo)
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Levi, Lorna R., Levi, Herbert W., Culin, Joseph. "spider". Encyclopedia Britannica, 27 Apr. 2025, https://www.britannica.com/animal/spider-arachnid. Accessed 10 May 2025.
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External Websites
  • AZ Animals - Spider
  • Arizona-Sonora Desert Museum - Spiders
  • Australian Museum - What is a spider?
  • Better Health Channel - Spiders
  • University of Minnesota Extension - Spider
  • University of Wisconsin-Madison - Wisconsin Horticulture Division of Extension - Garden Spiders
  • Burke Museum - Spider Myths
  • University of Missouri Extension - Spiders
  • Cell Press - Current Biology - The global spread of misinformation on spiders
Britannica Websites
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  • spider - Children's Encyclopedia (Ages 8-11)
  • spider - Student Encyclopedia (Ages 11 and up)