Forked tongue

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Forked tongue of a Carpet Python (Morelia spilota mcdowelli)

A forked tongue is a tongue split into two distinct tines at the tip; this is a feature common to many species of reptiles. Reptiles smell using the tip of their tongue, and a forked tongue allows them to sense from which direction a smell is coming. Sensing from both sides of the head and following trails based on chemical cues is called tropotaxis.[1] It is unclear whether forked-tongued reptiles can actually follow trails or if this is just a hypothesis.[2][3][4]

Forked tongues have evolved in these Squamate reptiles (lizards and snakes) for various purposes. The advantage to having a forked tongue is that more surface area is available for the chemicals to contact and the potential for tropotaxis.[5] The tongue is flicked out of the mouth regularly to sample the chemical environment. This form of chemical sampling allows these animals to sense non-volatile chemicals, which cannot be detected by simply using the olfactory system.[6][7][8] This increased ability to sense chemicals has allowed for heightened abilities to identify prey, recognize kin, choose mates, locate shelters, follow trails, and more.[9]

Forked tongues have evolved multiple times in Squamates. It is unclear, based on the morphological and genetic evidence, where the exact points of change are from a notched tongue to a forked tongue, but it is believed that the change has happened two to four times.[10][11] A common behavioral characteristic that has evolved in those with forked tongues is that they tend to be wide foragers.[12][13]

Hummingbirds also have tongues that split at the tip.[14] Galagos (bushbabies) have a secondary tongue, or sublingua, used for grooming, hidden under their first.[15]

Usage as First Nations cultural term[edit]

The phrase "speaks with a forked tongue" means to deliberately say one thing and mean another or, to be hypocritical, or act in a duplicitous manner. In the longstanding tradition of many Native American tribes, "speaking with a forked tongue" has meant lying, and a person was no longer considered worthy of trust, once he had been shown to "speak with a forked tongue". This phrase was also adopted by Americans around the time of the Revolution, and may be found in abundant references from the early 19th century — often reporting on American officers who sought to convince the tribal leaders with whom they negotiated that they "spoke with a straight and not with a forked tongue" (as for example, President Andrew Jackson told the Creek Nation in 1829[16]). According to one 1859 account, the native proverb that the "white man spoke with a forked tongue" originated as a result of the French tactic of the 1690s, in their war with the Iroquois, of inviting their enemies to attend a Peace Conference, only to be slaughtered or captured.[17]

See also[edit]

References[edit]

  1. ^ Schwenk, K. 1994. Why snakes have forked tongues. Science 263:1573-1577.
  2. ^ Kubie, J. L., and M. Halpern. 1979. Chemical senses involved in garter snake prey trailing. Journal of Comparative and Physiological Psychology 93:648-667.
  3. ^ Waters, R. M. 1993, Odorizedair current trailing by garter snakes, Thamnophis sirtalis. Brain Behavior Evolution 41:219-223.
  4. ^ Parker, M. R., B. A. Young, and K. V. Kardong. 2008. The forked tongue and edge detection in snakes (Crotalus oreganus): an experimental test. Journal of Comparative Psychology 122:35-40.
  5. ^ Cooper, W. E. 1995a. Evolution and function of lingual shape in lizards, with emphasis on elongation, extensibility, and chemical sampling. Journal of Chemical Ecology 21:477-505.
  6. ^ Baxi, K. N., K. M. Dorries, and H. L. Eisthen. 2006. Is the vomeronasal organ system really specialized for detecting pheromones? Trends in Neurosciences 29:1-7.
  7. ^ Shine, R., X. Bonnet, M. J. Elphick, and E. G. Barrott. 2004. A novel foraging mode in snakes: browsing by the sea snake Emydocephalus annulatus (Serpentes, Hydrophiidae). Functional Ecology 18:16-24.
  8. ^ Schwenk, K. 1995. Of tongues and noses, chemoreception in lizards and snakes. Trends in Ecology & Evolution 10:7-12.
  9. ^ Schwenk, K. 1995. Of tongues and noses, chemoreception in lizards and snakes. Trends in Ecology & Evolution 10:7-12.
  10. ^ Schwenk, K. 1994. Why snakes have forked tongues. Science 263:1573-1577.
  11. ^ Townsend, T. M., A. Larson, E. Louis, and J. R. Macey. 2004. Molecular phylogenetics of Squamata: the position of snakes, Amphisbaenians, and Dibamids, and the root of the Squamate tree. Systematic Biology 53:735-757.
  12. ^ Schwenk, K. 1994. Why snakes have forked tongues. Science 263:1573-1577
  13. ^ Cooper, W. E. 1995b. Foraging mode, prey chemical discrimination, and phylogeny in lizards. Animal Behaviour 50:1709-1709.
  14. ^ Bill Hilton Jr (2007-06-12). "Hummingbird Internal Anatomy and Physiology". Operation RubyThroat: The Hummingbird Project. Hilton Pond Center for Piedmont Natural History. Retrieved 2008-02-13. The tongue itself splits in the floor of the mouth 
  15. ^ Monkeyland. "Bushbaby - Galago moholi". Meet Our Primates. Monkeyland Primate Sanctuary. Archived from the original on 2007-10-22. Retrieved 2008-02-13. equipped with a second, pointy tongue underneath their normal one 
  16. ^ Niles' Register, June 13, 1829
  17. ^ Transactions of the New York State Agricultural Society, Vol 19, 1859, p. 230.