First published online December 22, 2003
Journal of Experimental Biology 207, 461-474 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00769
Kinematics of the transition between aquatic and terrestrial locomotion in the newt Taricha torosa
Miriam A. Ashley-Ross* and
Brett F. Bechtel
Department of Biology, Box 7325, Wake Forest University,
Winston-Salem, NC 27109, USA
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Fig. 1. Schematic of the experimental setup for videotaping sequences. The chamber
is a 40-liter aquarium partially filled with water. For clarity, the front
wall of the aquarium has been omitted from the illustration.
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Fig. 2. Representative sequence of Taricha walking down a ramp into water
and the transition to swimming. Panels are in sequence vertically and are each
separated in time by 100 ms. In each panel, the top figure is a dorsal view,
and the bottom figure is a synchronous lateral view. Both cameras were rotated
to align with the ramp surface; the light-appearing diagonal line in the left
half of each lateral view is the air–water interface. Note the almost
complete immersion before the transition to swimming (right column). Images
were cropped and composited in Adobe Photoshop 7.
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Fig. 3. Representative sequence of Taricha walking from water up a ramp.
Panels are in sequence vertically and are each separated in time by 100 ms. In
each panel, the top figure is a dorsal view, and the bottom figure is a
synchronous lateral view. Both cameras were rotated to align with the ramp
surface; the light-appearing diagonal line in the left half of each lateral
view is the air–water interface. Note that walking commences while the
newt is still submerged (left column). Images were cropped and composited in
Adobe Photoshop 7.
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Fig. 4. Stride durations (A), relative stride lengths (B) and velocity (C) for
ramp-to-water (filled circles) and water-to-ramp (open squares) sequences.
Values are means ± 1 S.E.M. During the individual strides
Ramp 2 and 3, the newt is completely out of water; in Water 2 and 3, the newt
has all four limbs in the water. The transition between media occurs in
strides Ramp 1 and Water 1. Arrows indicate the direction of locomotion.
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Fig. 5. Gait diagrams for transitional locomotion sequences in Taricha.
Bars indicate periods during which the foot is on the ground. Thin bars
indicate one S.E.M. of foot placement or lifting. LH, left
hindfoot; LF, left forefoot; RF, right forefoot; RH, right hindfoot. (A)
Water-to-ramp: transition between swimming/underwater walking and terrestrial
walking. Thin gray lines separate strides. The light gray region indicates the
stride during which the feet leave the water; the dark gray region indicates
the stride in which all feet had left the water. Note decreasing variation in
footfalls (shorter error bars) as the animal leaves the water. Mean of 20
sequences. (B) Ramp-to-water: transition between walking and swimming. Thin
gray lines separate strides. The light gray region indicates the stride during
which the feet enter the water; the dark gray region indicates the stride in
which all feet had entered the water. For ease of comparison with Up patterns,
the Down sequence has been reversed. Note increasing variation in footfalls
(longer error bars) as the animal enters the water. Mean of 20 sequences. The
large arrows above each panel indicate the direction of motion.
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Fig. 6. Average kinematic profiles of two-dimensional pectoral girdle, pelvic
girdle and overall trunk angles for Up (water-to-ramp; left panels) and Down
(ramp-to-water; right panels) sequences. Symbols indicate mean values; error
bars are S.E.M. The solid blue line is the smoothed average (see
Materials and methods). Gray regions are as in
Fig. 5. All strides begin and
end with the strike of the left hindfoot. Arrows above each panel indicate the
direction of motion; Down sequences have been reversed to facilitate
comparison across analogous strides.
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Fig. 7. Average kinematic profiles of two-dimensional angles between the pectoral
girdle and humerus and between the pelvic girdle and femur for Up
(water-to-ramp; left panels) and Down (ramp-to-water; right panels) sequences.
Format of the figure follows the conventions of
Fig. 6.
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Fig. 8. Average kinematic profiles of three-dimensional angles between the humerus
and forearm and between the femur and crus for Up (water-to-ramp; left panels)
and Down (ramp-to-water; right panels) sequences. Format of the figure follows
the conventions of Fig. 6.
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Fig. 9. Average kinematic profiles of three-dimensional angles between the humerus
and ramp surface and between the femur and ramp surface for Up (water-to-ramp;
left panels) and Down (ramp-to-water; right panels) sequences. Format of the
figure follows the conventions of Fig.
6.
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Fig. 10. Average kinematic profiles of three-dimensional angles between the forearm
and ramp surface and between the crus and ramp surface for Up (water-to-ramp;
left panels) and Down (ramp-to-water; right panels) sequences. Format of the
figure follows the conventions of Fig.
6.
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© The Company of Biologists Ltd 2004
