QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online August 31, 2004
Journal of Experimental Biology 207, 3483-3494 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01170

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Young, B. A. Articles by Singer, M. Search for Related Content PubMed PubMed Citation Articles by Young, B. A. Articles by Singer, M. Social Bookmarking                         What's this?

The buccal buckle: the functional morphology of venom spitting in cobras

Bruce A. Young^*, Karen Dunlap, Kristen Koenig and Meredith Singer

Department of Biology, Lafayette College, Easton, PA 18042, USA

^* Author for correspondence at present address: School of Biological Sciences, PO Box 664236, Washington State University, Pullman, WA 99164-4236, USA (e-mail: youngb{at}wsu.edu)

Accepted 5 July 2004

Multiple radiations of Asiatic and African cobras have independently evolved the ability to expel their venom as a pressurized horizontal stream, a behavior commonly referred to as spitting. Though the unique fang morphology of spitting cobras is well known, the functional bases of venom spitting have received little attention. The combined results of gross and microscopic morphology, high-speed digital videography, experimental manipulations of anesthetized cobras and electromyography reveal a two-part mechanism for spitting venom. Contraction of the M. protractor pterygoideus (PP) causes displacement and deformation of the palato-maxillary arch and fang sheath; ultimately this displacement removes soft tissue barriers to venom flow that are normally present within the fang sheath. The M. adductor mandibulae externus superficialis (AMES) is activated simultaneously with the PP; the AMES increases venom pressure within the venom gland, propelling a stream of venom through the venom duct and out the fang. The displacements of the palato-maxillary arch, which form the first part of the spitting mechanism, are very similar to the motions of these bones during prey ingestion (the pterygoid walk), suggesting that venom spitting may have evolved from a specialization of prey ingestion, rather than prey capture.

Key words: snake, reptile, fluid pressure, dentition, defensive behavior, venom

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				B. G. Fry, H. Scheib, L. van der Weerd, B. Young, J. McNaughtan, S. F. R. Ramjan, N. Vidal, R. E. Poelmann, and J. A. Norman Evolution of an Arsenal: Structural and Functional Diversification of the Venom System in the Advanced Snakes (Caenophidia) Mol. Cell. Proteomics, February 1, 2008; 7(2): 215 - 246. [Abstract] [Full Text] [PDF]