Comparison of Tongue Extrusions in Representatives of Six Families of Lizards

Abstract

Many species of lizards extend the tongue frequently under natural conditions. Several reasons, including chemoreception, have been hypothesized for this behavior but sufficient quantitative data have not been collected to indicate its importance. Baseline rates of tongue extrusions for 6 different families of captive lizards were compared and significant differences between all 6 families were found. The range of variation in frequency was from a low of 3.4 tongue extrusions/30 min for the Cordylidae to a high of 299.5/30 min for the Teiidae. The frequency of tongue extrusions was Cordylidae < Iguanidae < Gerrhosauridae < Scincidae < Helodermatidae < Teiidae. An increase in the frequency of tongue extrusions may be correlated with increased bifurcation of the tongue. Possible uses of this tongue extrusion are explored for the 6 different families. The differences in frequency of tongue extrusion in different families may indicate the relative importance of the tongue-Jacobson''s organ system.