Predation by Spitting Spiders: Elaborate Venom Gland, Intricate Delivery System



Spitting spiders (Araneae: Scytodidae) subdue prey by entangling them at a distance with a mixture of silk, glue, and perhaps venom. All of the components of this mixture originate in the venom glands, a pair of relatively elaborate structures consisting of five histologically distinct regions, the anterior three producing venom and the posterior two, comprising the largest lobe of the gland, producing silk and glue. The venom gland and its products anchor a suite of tightly linked adaptations that constitute the predatory system of these remarkable spiders. The spitting requires considerable metabolic expenditure both in the form of maintenance of impressively large venom glands and in the form of the biosynthesis of the proto-silk and the glue that are the primary constituents of the spit. Sensory input allowing identification and localization of the potential prey and neural coordination of the spit ejection itself also must occur. It may be that an important part of expectoration, the oscillations of the fangs (contributing to the zigzag pattern of spit that effectively covers a prey item), once triggered, does not require further neural input, but that possibility remains to be confirmed. The chemical, physical, and microfluidic properties of the proto-silk and glue mixture are also crucial for the proper functioning of the spitting system; at the moment, these properties are poorly understood except insofar as they may be similar to the analogous properties of the proto-silk and glue produced in the opisthosomal silk glands of spiders.


  1. Anderson JF, Prestwich KN (1975) The fluid pressure pumps of spiders (Chelicerata, Araneae). Z Morph Tiere 81:257–277CrossRefGoogle Scholar
  2. Binford G (2013) The evolution of a toxic enzyme in sicariid spiders. In: Nentwig W (ed) Spider ecophysiology. Springer, Heidelberg (this volume)Google Scholar
  3. Binford GJ, Wells MA (2003) The phylogenetic distribution of sphingomyelinase D activity in venoms of haplogyne spiders. Comp Biochem Physiol B 135:25–33PubMedCrossRefGoogle Scholar
  4. Choresh O, Bayarmagnai B, Lewis RV (2009) Spider web glue: two proteins expressed from opposite strands of the same DNA sequence. Biomacromolecules 10:2852–2856PubMedCrossRefGoogle Scholar
  5. Clements R, Li D (2005) Regulation and non-toxicity of the spit from the pale spitting spider Scytodes pallida (Araneae: Scydodidae). Ethology 111:311–321CrossRefGoogle Scholar
  6. Coddington JA (2005) Phylogeny and classification of spiders. In: Ubick D, Paquin P, Cushing PE, Roth V (eds) Spiders of North America: an identification manual. American Arachnological SocietyGoogle Scholar
  7. Eberhard WG (1987) How spiders initiate airborne lines. J Arachnol 15:1–9Google Scholar
  8. Foelix RF (2011) Biology of spiders. Oxford University Press, OxfordGoogle Scholar
  9. Gardner T, Cecchi G, Magnasco M, Laje R, Mindlin GB (2001) Simple motor gestures for birdsongs. Phys Rev Lett 87:208101–1CrossRefGoogle Scholar
  10. Gilbert C, Rayor LS (1985) Predatory behavior of spitting spiders (Araneae: Scytodidae) and the evolution of prey wrapping. J Arachnol 13:231–241Google Scholar
  11. Japyassú HF, Machado FA (2010) Coding behavioural data for cladistic analysis: using dynamic homology without parsimony. Cladistics 26:625–642CrossRefGoogle Scholar
  12. Josephson RK, Malamud JG, Stokes DR (2000) Asynchronous muscle: a primer. J Exp Biol 203:2713–2722PubMedGoogle Scholar
  13. Kerkam K, Viney C, Kaplan D, Lombardi S (1991) Liquid crystallinity of natural silk secretions. Nature 349:596–598CrossRefGoogle Scholar
  14. Kovoor J (1987) Comparative structure and histochemistry of silk-producing organs in arachnids. In: Nentwig W (ed) Ecophysiology of spiders. Springer, BerlinGoogle Scholar
  15. Kovoor J, Zylberberg L (1972) Histologie et infrastructure de la glande chélicérienne de Scytodes delicatula Sim. (Araneidae, Scytodidae). Ann Sci Nat Zool 14:333–388Google Scholar
  16. Kropf C (2013) Hydraulic system of locomotion. In: Nentwig W (ed) Spider ecophysiology. Springer, Heidelberg (this volume)Google Scholar
  17. Opell BD, Hendricks ML (2010) The role of granules within viscous capture threads of orb-weaving spiders. J Exp Biol 213:339–346PubMedCrossRefGoogle Scholar
  18. Sahni V, Blackledge TA, Dhinojwala A (2010) Viscoelastic solids explain spider web stickiness. Nat Commun 1:19. doi:10.1038/ncomms1019 PubMedCrossRefGoogle Scholar
  19. Sensenig AT, Shultz JW (2003) Mechanics of cuticular elastic energy storage in leg joints lacking extensor muscles in arachnids. J Exp Biol 206:771–784PubMedCrossRefGoogle Scholar
  20. Suter RB (1999) An aerial lottery: the physics of ballooning in a chaotic atmosphere. J Arachnol 27:281–293Google Scholar
  21. Suter RB, Stratton GE (2005) Scytodes vs. Schizocosa: predatory techniques and their morphological correlates. J Arachnol 33:7–15CrossRefGoogle Scholar
  22. Suter RB, Stratton GE (2009) Spitting performance parameters and their biomechanical implications in Scytodes (Araneae, Scytodidae). J Insect Sci 9:62, CrossRefGoogle Scholar
  23. Suter RB, Stratton GE (2011) Does allometric growth explain the diminutive size of the fangs of Scytodes (Araneae, Scytodidae)? J Arachnol 39:174–177CrossRefGoogle Scholar
  24. Syme DA, Josephson RK (2002) How to build fast muscles: synchronous and asynchronous designs. Integr Comp Biol 42:762–770PubMedCrossRefGoogle Scholar
  25. Townley MA, Tillinghast E (2013) Aggregate silk gland secretions of araneoid spiders. In: Nentwig W (ed) Spider ecophysiology. Springer, Heidelberg (this volume)Google Scholar
  26. Vogel S (2009) Glimpses of creatures in their physical worlds. Princeton University Press, PrincetonGoogle Scholar
  27. Vollrath F, Knight DP (2001) Liquid crystalline spinning of spider silk. Nature 410:541–548PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Department of BiologyVassar CollegePoughkeepsieUSA
  2. 2.Department of BiologyUniversity of Mississippi, UniversityOxfordUSA

Personalised recommendations