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

This Article Summary 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 Burrows, M. Articles by Morris, O. Search for Related Content PubMed PubMed Citation Articles by Burrows, M. Articles by Morris, O.

Jumping and kicking in bush crickets

Malcolm Burrows^* and Oliver Morris

Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK

View larger version (64K): [in a new window]   Fig. 1. Photographs of adult females of the four species of bush cricket used in this study: (A) Pholidoptera griseoaptera; (B) Leptophyes punctatissima; (C) Meconema thalassinum and (D) Conocephalus dorsalis. Scale bars, 10 mm (A—C); 15 mm (D).

View larger version (58K): [in a new window]   Fig. 2. Anatomy of the femoro-tibial joint of a left hind leg of an adult female Pholidoptera. (A) Photograph of the posterior (= medial) surface. The distal femur has a semi-lunar shaped groove. The flexor tibiae tendon inserts around a V-shaped rim of the ventral tibia. (B) A cleared leg viewed ventrally with the tibia almost flexed about the femur to show the black and opposed, flat regions of the femur and tibia that form the hinge joint. (C) The same leg as in B, viewed as in A to reveal the tendons of the flexor and extensor tibiae muscle and the apodeme of the femoral chordotonal organ (FeCO). The extensor tendon expands distally before inserting on the dorsal rim of the tibia. (D) Tracings from camera lucida drawings of the position of the tibia as it rotates about the femur. Nine positions of the tibia are shown as black lines with an outline of the tibia superimposed on a thicker line in position 2. The insertions of the flexor (red) and extensor (green) tibiae tendons are indicated. The structural reinforcing elements of the distal femur are in blue. Measurements made from this drawing were used to estimate the flexor and extensor lever arms at different joint angles, shown in the inset graph.

View larger version (57K): [in a new window]   Fig. 3. Kicking movements of a female Pholidoptera illustrated by selected frames captured at 1000 frames s-1. (A) A kick by the right hind leg. At -37 ms, this leg was touched by a small paint brush (top left of frame). The right hind leg rotated forwards so that the tarsus was lifted from the ground and the tibia was fully flexed about the femur (-14 ms). From this position, the tibia was extended rapidly while the left hind leg remained in a constant position. Full extension was achieved at 0 ms. (B) A kick by both hind legs. At -46 ms, the ovipositor was touched by the paint brush and both hind legs rotated forwards but the tibiae were not fully flexed (-12 ms). From this position, the tibiae of both legs were then extended rapidly, with the right hind leg reaching full extension at 0 ms.

View larger version (65K): [in a new window]   Fig. 4. Kicks of different velocities and from different femoro-tibial starting angles. (A) Changes of the femoro-tibial angle during four kicks by the same Pholidoptera aligned at the time of maximal extension (0 ms). Kick 2 started from a partly extended femoro-tibial angle but still achieved the same maximal rotational velocity (65 000 deg. s-1) as kick 1, which started from a fully flexed position. The rebound movement at full extension is plotted for kick 1. Kicks 3 (28 000 deg. s-1) and 4 (14 000 deg. s-1) are slower. (B) Movements of the femoro-tibial joint during a kick captured at 1000 frames s-1 and with an exposure of 0.25 ms. The tibia was fully flexed about the femur in the first frame (-34 ms). From the start of the first detectable extension movement (-7 ms) to full extension (0 ms) of the tibia took 7 ms. The crosshairs marking the anterior edge of the semi-lunar groove in the first six frames do not shift in position. (C) The femoro-tibial joint viewed end-on during a kick. There was no distortion of the distal femur either before (-13 ms) or during (-7 ms and -3 ms) the kick. The proximal part of the femur and the bush cricket itself were fixed in Plasticine.

View larger version (27K): [in a new window]   Fig. 5. Variation in the motor pattern for kicking in Pholidoptera. The extracellular recordings are from the flexor and extensor tibiae muscles of restrained animals (A is from one animal, B—D from another). Images (not shown) of the movements of the tibia were captured to enable the peak angular velocity of the tibia (measured in deg. s-1) and the timing of the kick (indicated by vertical arrows) to be determined. (A,B) Kicks involving no apparent co-contraction of flexor and extensor tibiae muscles. In A, a slow kick results from a few spikes in flexor tibiae motor neurones followed, after a delay, by two spikes in fast extensor tibiae motor neurones (FETi). In B, a prolonged flexion followed by three spikes in FETi results in a slightly faster extension of the tibia. (C,D) Kicks resulting from co-contractions. In C, the flexor motor neurones spike first and continue while six spikes of FETi occur. There is then a pause of almost 100 ms without motor activity before a slow tibial extension occurs. In D, a co-contraction of flexor and extensor tibiae motor neurones is followed immediately by a rapid extension of the tibia in a kick. In C and D, a movement artefact occurred at the time of the rapid extension of the tibia.

View larger version (28K): [in a new window]   Fig. 6. Linear relationship between the maximal rotational velocity of the tibia during a kick and the number of spikes in the fast extensor tibiae motor neurone (FETi). The greater the number of spikes, the higher the speed of rotation, but there is variation in speed for a given number of spikes in different kicks. Data from 45 kicks by six Pholidoptera are pooled. The line was fitted by linear regression y=0.83+8420x (P<0.001, r2=0.78).

View larger version (23K): [in a new window]   Fig. 7. Comparison of the muscular activity and tibial movements underlying two kicks by the same Pholidoptera. (A) A kick from an initial position where the tibia was fully flexed about the femur (kick 1 in Fig. 4A). Spikes in fast extensor tibiae motor neurone (FETi) stop before the tibia extends rapidly (65 000 deg. s-1) in a kick. (B) A second kick by the same animal (kick 2 in Fig. 4A). The tibia is first fully flexed but then extends by 27°. It remains in this partially flexed position while FETi spikes continue, until it suddenly extends rapidly (65 000 deg. s-1) in a kick. The maximal angular velocity of the tibial movements was the same in both kicks. The electrical activity of the extensor tibiae muscle was recorded at the same time as the tibial movements that are plotted from sequences of images captured at 1000 frames s-1.

View larger version (52K): [in a new window]   Fig. 8. Jumping in Pholidoptera. (A) Graphs of the changes in the femoro-tibial angle, body height and velocity of body movement during a jump by a male. The body was accelerated at 112 m s-2 during the last 5 ms before takeoff at a velocity of 1.75 m s-1. (B) Selected frames from the same jump viewed from the side. At the start, the tibia was not fully flexed about the femur but was then extended rapidly to push the body forwards and upwards. (C) A second jump by the same animal viewed headon. The hind legs were first rotated outwards at the coxa joint with the thorax, and the tibia extends so that the body was raised from the ground. The front and middle legs left the ground before the hind legs.

View larger version (30K): [in a new window]   Fig. 9. The trajectory of a female Pholidoptera during a jump. The graph plots the upwards and forwards movement of the body, and the selected frames show the propulsive extension of the hind tibiae. After takeoff, the hind legs were swung forward so that they were above the body. The numbers give the time before and after takeoff at 0 ms.

View larger version (32K): [in a new window]   Fig. 10. Jumping in Meconema and Conocephalus. (A) Two jumps by the same female Meconema. Four selected images of one jump captured at 500 frames s-1 show the hind legs were not fully flexed before they were extended rapidly. The changes in the femoro-tibial angle and speed of body movement are plotted from a second jump with a takeoff velocity of 1.6 m s-1 captured at 1000 frames s-1. (B) Selected images and plots of the femorotibial angle and speed of body movement from the same jump by a male Conocephalus taking off at a velocity of 1.0 m s-1 captured at 1000 frames s-1.