First published online February 13, 2009
Journal of Experimental Biology 212, 604-609 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.024349
Losing stability: tail loss and jumping in the arboreal lizard Anolis carolinensis
Gary B. Gillis1,*,
Lauren A. Bonvini1,
and
Duncan J. Irschick2
1 Department of Biological Sciences, Mount Holyoke College, South Hadley, MA
01075, USA
2 Department of Biology and Organismal and Evolutionary Biology Graduate
Program, University of Massachusetts, Amherst, MA 01003, USA
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Fig. 1. Method for measuring body and tail base angle during jumping. Body angle
was measured relative to the horizontal using a line connecting points on the
lateral surface of the animal's body at the level of the pectoral and pelvic
girdles. Tail base angle was measured relative to the body angle and was
measured using a line connecting points on the lateral surface of the animal's
body at the level of the vent and at 20% tail length (also the point of tail
removal).
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Fig. 2. Four key jump variables (takeoff velocity, takeoff duration, takeoff angle
and jump distance) do not differ significantly between lizards before and
after tail removal. Values shown are the average of individual
means±s.e.m. (N=6 individuals).
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Fig. 3. Body angles during jumping before and after tail removal. (A) Movie stills
taken from the same lizard before and after tail removal at five points during
a jump: takeoff, 25%, 50% and 75% during the aerial phase and at landing.
White lines are drawn to highlight the orientation of the body and tail base.
Note the `head over heels' pitch in the lower panel showing the tailless
lizard. (B) Mean body angles, relative to the horizontal, from all jumps in
all lizards. Body angle diverges significantly in tailless lizards by the
halfway point of the aerial phase, Values shown are the average of individual
means±s.e.m. (N=6 individuals).
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Fig. 4. Tail base angles during jumping before and after tail removal. (A)
Representative data from four jumps (each jump is represented by a different
line) of a single lizard showing patterns of tail base movement during
jumping. Note how the tail base is raised as the animal approaches takeoff,
after which it returns to lower values for the rest of the jump
(typically<20 deg.). (B) Data from the same lizard following tail removal.
The pattern is similar until shortly after takeoff when the tail angle gets
consistently higher, reflecting vigorous rotation of the tail base, presumably
to try to correct body orientation as the animal pitches out of control.
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Fig. 5 Tail–substrate interactions after takeoff. (A) Movie stills of a
lizard with its tail intact at three points early in a jump: takeoff, shortly
after takeoff and in mid-air. At takeoff, the base of the lizard's tail is
raised and in this jump the entire tail is lifted off of the jump platform
(white arrow in left-most image). Shortly after takeoff, the tail slaps down
onto the platform and drags along it for a brief period (white arrow in center
image). We hypothesize that such tail–substrate interactions generate
forces that counteract posterior rotation of the body. (B) High-speed video
images of the same lizard at similar points in a jump after tail removal.
Shortly after takeoff, the body is in a comparable orientation; however,
without the tail–substrate interactions, once the animal is in mid-air,
exaggerated posterior rotation of the body begins.
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© The Company of Biologists Ltd 2009
