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| JEB：跳蚤跳跃靠脚尖而不是膝部 |
| 添加时间：2011-01-27 13:29:22 浏览次数：1747
来源：生物谷
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花了44年，使用了高速摄像机、电子显微镜和数学模型，研究人员才最终发现跳蚤跳跃靠的是脚尖而不是膝部。
自1967年以来，人们就知道跳蚤如何为跳得快、跳得高而积蓄能量，但人们过去一直就跳蚤如何将这些能量转移到地面以便起跳而争论不休。
在《实验生物学杂志》（Journal of Experimental Biology）上刊登的一篇长达12页的论文中，剑桥大学动物学家格雷戈里·萨顿等人称，他们拍摄了10只成年跳蚤进行的51次跳跃。他们“对跳跃轨迹、线速度和角速度都进行了测量”。
对录像片段进行的分析显示，跳跃过程开始于跳蚤将一个关节卡在身体和两条后腿之间。然后它会收缩两块肌肉。这会压缩含有节肢弹性蛋白的一部分身体，从而有效引起一种生物弹力。当跳蚤释放这种弹力时，能量通过其腿部传导，它的腿部充当了杠杆，脚尖受到压迫。
这一动作使重为0.7毫克的跳蚤能以每秒1.9米的速度跳跃。（生物谷Bioon.com）
生物谷推荐原文出处：
Journal of Experimental Biology doi: 10.1242/jeb.052399
Biomechanics of jumping in the flea
Gregory P. Sutton* and Malcolm Burrows
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
It has long been established that fleas jump by storing and releasing energy in a cuticular spring, but it is not known how forces from that spring are transmitted to the ground. One hypothesis is that the recoil of the spring pushes the trochanter onto the ground, thereby generating the jump. A second hypothesis is that the recoil of the spring acts through a lever system to push the tibia and tarsus onto the ground. To decide which of these two hypotheses is correct, we built a kinetic model to simulate the different possible velocities and accelerations produced by each proposed process and compared those simulations with the kinematics measured from high-speed images of natural jumping. The in vivo velocity and acceleration kinematics are consistent with the model that directs ground forces through the tibia and tarsus. Moreover, in some natural jumps there was no contact between the trochanter and the ground. There were also no observable differences between the kinematics of jumps that began with the trochanter on the ground and jumps that did not. Scanning electron microscopy showed that the tibia and tarsus have spines appropriate for applying forces to the ground, whereas no such structures were seen on the trochanter. Based on these observations, we discount the hypothesis that fleas use their trochantera to apply forces to the ground and conclude that fleas jump by applying forces to the ground through the end of the tibiae.
Key words: trajectory control, kinematics, Siphonaptera
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