Four species of salamander of the family Plethodontidae were examined using electromyographic (EMG) recording during prey-capture behavior to test the hypotheses that the tongue retractor, tongue protractor and jaw depressor muscles are activated simultaneously and in a stereotyped pattern, as was found in other salamanders, and to determine whether species with different tongue morphologies and tongue protraction abilities exhibit different motor control strategies. The results show that sequential activation was observed far more frequently than simultaneous activation; the jaw depressor muscle was activated first, followed by the tongue protractor and then the tongue retractor. Species with short, attached tongues (Desmognathus quadramaculatus and Plethodon jordani) showed simultaneous activation more often than species with long, free tongues (Pseudotriton ruber and Hydromantes supramontis), which showed strongly non-simultaneous activation. Most EMG variables showed no effect of prey-capture success, suggesting that sensory feedback is not involved in modulating the motor pattern during the prey-capture strike. Hydromantes supramontis was examined for modulation of its motor pattern in response to prey distance, and several EMG variables were found to be positively correlated with tongue protraction distance. The motor pattern of strongly non-simultaneous activation of antagonistic tongue muscles has evolved along with the evolution of long, free tongues in plethodontids. The variable motor patterns observed provide further evidence that amphibian feeding in general is not as highly stereotyped as has been previously thought.

REFERENCES

Deban
S. M.
(
1997
).
Modulation of prey-capture behavior in the plethodontid salamander Ensatina eschscholtzii
.
J. Exp. Biol
20
,
1951
–.
Deban
S. M.
,
Nishikawa
K. C.
(
1992
).
The kinematics of prey capture and the mechanism of tongue protraction in the green tree frog Hyla cinerea
.
J. Exp. Biol
170
,
235
–.
Deban
S. M.
,
Wake
D. B.
,
Roth
G.
(
1997
).
Salamander with a ballistic tongue
.
Nature
389
,
27
–.
Elwood
J. R. L.
,
Cundall
D.
(
1994
).
Morphology and behavior of the feeding apparatus in Cryptobranchus alleganiensis (Amphibia: Caudata)
.
J. Morph
220
,
47
–.
Erdman
S.
,
Cundall
D.
(
1984
).
The feeding apparatus of the salamander Amphiuma tridactylum: morphology and behavior
.
J. Morph
181
,
175
–.
Gans
C.
,
Gorniak
G. C.
(
1982
).
Functional morphology of lingual protrusion in marine toads (Bufo marinus)
.
Am. J. Anat
163
,
195
–.
Jackman
T. R.
,
Applebaum
G.
,
Wake
D. B.
(
1997
).
Phylogenetic relationships of bolitoglossine salamanders: A demonstration of the effects of combining morphological and molecular data sets
.
Mol. Biol. Evol
14
,
883
–.
Larsen
J. H.
Jr.
,
Beneski
J. T.
Jr.
(
1988
).
Quantitative analysis of feeding kinematics in dusky salamanders (Desmognathus)
.
Can. J. Zool
66
,
1309
–.
Larsen
J. H.
Jr.
,
Beneski
J. T.
,
Miller
B. T.
(
1996
).
Structure and function of the hyolingual system in Hynobius and its bearing on the evolution of prey capture in terrestrial salamanders
.
J. Morph
227
,
235
–.
Larsen
J. H.
Jr.
,
Beneski
J. T.
,
Wake
D. B.
(
1989
).
Hyolingual feeding systems of the Plethodontidae: comparative kinematics of prey capture by salamanders with free and attached tongues
.
J. Exp. Zool
252
,
25
–.
Larsen
J. H.
Jr.
,
Guthrie
D. J.
(
1975
).
The feeding system of terrestrial tiger salamanders (Ambystoma tigrinum melanostictum Baird)
.
J. Morph
147
,
137
–.
Lauder
G. V.
,
Shaffer
H. B.
(
1988
).
Ontogeny of functional design in tiger salamanders (Ambystoma tigrinum): are motor patterns conserved during major morphological transformations?
.
J. Morph
197
,
249
–.
Lombard
R. E.
,
Wake
D. B.
(
1976
).
Tongue evolution in thelungless salamanders, Family Plethodontidae. I. Introduction, theory and a general model of dynamics
.
J. Morph
148
,
265
–.
Lombard
R. E.
,
Wake
D. B.
(
1977
).
Tongue evolution in the lungless salamanders, Family Plethodontidae. II. Function and evolutionary diversity
.
J. Morph
153
,
39
–.
Lombard
R. E.
,
Wake
D. B.
(
1986
).
Tongue evolution in the lungless salamanders, Family Plethodontidae. IV. Phylogeny of plethodontid salamanders and the evolution of feeding dynamics
.
Syst. Zool
35
,
532
–.
Lorenz
K.
(
1937
).
Über die Bildung des Instinktbegriffes
.
Naturwissenschaften
25
,
289
–.
Maglia
A. M.
,
Pyles
R. A.
(
1995
).
Modulation of prey-capture behavior in Plethodon cinereus (Green) (Amphibia: Caudata)
.
J. Exp. Zool
272
,
167
–.
Marsden
C. D.
,
Rothwell
J. C.
,
Day
B. L.
(
1984
).
The use of peripheral feedback in the control of movement
.
Trends Neurosci
7
,
253
–.
Miller
B. T.
,
Larsen
J. H.
Jr.
(
1990
).
Comparative kinematicsof terrestrial prey capture in salamanders and newts (Amphibia: Urodela: Salamandridae)
.
J. Exp. Zool
256
,
135
–.
Nishikawa
K. C.
,
Anderson
C. W.
,
Deban
S. M.
,
O'Reilly
J. C.
(
1992
).
The evolution of neural circuits controlling feeding behavior in frogs
.
Brain Behav. Evol
40
,
125
–.
Nishikawa
K. C.
,
Gans
C.
(
1996
).
Mechanisms of tongue protraction and narial closure in the marine toad Bufo marinus
.
J. Exp. Biol
199
,
2511
–.
Pearson
K. G.
(
1993
).
Common principles of motor control in vertebrates and invertebrates
.
Annu. Rev. Neurosci
16
,
265
–.
Regal
P. J.
(
1966
).
Feeding specializations and the classification of terrestrial salamanders
.
Evolution
20
,
392
–.
Reilly
S. M.
,
Lauder
G. V.
(
1989
).
Physiological bases of feeding behavior in salamanders: do motor patterns vary with prey type?
.
J. Exp. Biol
141
,
343
–.
Reilly
S. M.
,
Lauder
G. V.
(
1992
).
Morphology, behavior and evolution: comparative kinematics of aquatic feeding in salamanders
.
Brain Behav. Evol
40
,
182
–.
Ritter
D.
,
Nishikawa
K.
(
1995
).
The kinematics and mechanism of prey capture in the African pig-nosed frog (Hemisus marmoratum): description of a radically divergent anuran tongue
.
J. Exp. Biol
198
,
2025
–.
Roth
G.
(
1976
).
Experimental analysis of the prey catching behavior of Hydromantes italicus Dunn (Amphibia, Plethodontidae)
.
J. Comp. Physiol
109
,
47
–.
Schwenk
K.
,
Wake
D. B.
(
1993
).
Prey processing in Leurognathus marmoratus and the evolution of form and function in desmognathine salamanders (Plethodontidae)
.
Biol. J. Linn. Soc
49
,
141
–.
Shaffer
H. B.
,
Lauder
G. V.
(
1985
).
Patterns of variation in aquatic ambystomatid salamanders: kinematics of the feeding mechanism
.
Evolution
39
,
83
–.
Thexton
A. J.
,
Wake
D. B.
,
Wake
M. H.
(
1977
).
Tongue function in the salamander Bolitoglossa occidentalis
.
Arch. Oral Biol
22
,
361
–.
Wainwright
P. C.
,
Richard
B. A.
(
1995
).
Scaling the feeding mechanism of the largemouth bass (Micropterus salmoides): motor pattern
.
J. Exp. Biol
198
,
1161
–.
This content is only available via PDF.