Study On Morphology And Jumping Behavior Of Pygmy Mole Crickets

Pygmy mole crickets has unique body structure and movement pattern which has the characteristics of flexible movement and adaptability to different media.The jumping ability of pygmy mole crickets are superior,so it is an excellent bionic model.However,The research of morphology and motion mechanism of pygmy mole crickets are still in its infancy both internationally and domestically.This article takes the pygmy mole cricket as the main research object,the surface microstructure characteristics of Pygmy mole crickets were obtained,through the comprehensive study of the observation of the body suface morphology and limb characteristic structure.At the same time,the platform of jumping movement information collection was built,the jumping process of crida cinerea,Locusta migratoria manilensis and pygmy mole cricket were recorded and analyzed.The kinematic model of the pygmy mole cricket at the take-off stage was established to explore the jumping motion patterns.The details are as follows:The biological structure and microscopic surface characteristics of the pygmy mole crickets were analyzed by stereo microscope and ultra-depth-of-field electron microscope.The results showed that: the micro morphology of the head of pygmy mole cricket is convex hull shape,and the micro morphology of the pronotum of pygmy mole cricket is compound convex hull shape.the basic unit morphology of is different between head and pronotum;The microscopic surface of the front wing of the pygmy mole cricket contains convex hull shape,scale shape,pit shape and dent shape,which exist in a composite form;The microscopic surface of hind wings of pygmy mole cricket have convex hull shape and scale shape.According to the degree of hardening and the surface microscopic morphology,the lateral sides of the hind femur tibia joints of the hind leg of the pygmy mole cricket can be divided into six parts: Semi-lunar process,Quasi semi-lunar process,Tail membranous area,Center membranous area,Cover plate and Sub-cover plate;the medial sides of the hind femur tibia joints of the hind leg of the pygmy mole cricket can be divided into six parts: Semi-lunar process,Quasi semi-lunar process,Quasi membranous area,Medial membranous area,Medial cover plate and Sub-medial cover plate.The hind tibia present a convex hull shape when fully extension,and a scaly shape when fully flexed.There are terminal hook at the distal end of long apical spurs and short sub-apical spurs.This feature combined with the living habits of pygmy mole crickets,can inferred that the microscopic surface characteristics and biological morphology are related to their living environment.An insect jumping kinematics information collection platform was set up,we research the characteristic structures and regular pattern of joint changes of Acrida cinerea,Locusta migratoria manilensis and pygmy mole cricket by speed camera systems and Image analysis software(tracker).The mathematical model of correction to space linear which has symmetrical feature is established to improve the accuracy of data.The results showed that the three orthoptera insects all completed the take-off with the rapid extension of the hind legs.The jumping patterns of the Acrida cinerea and the Locusta migratoria manilensis are the same,but the coordination methods between the characteristic structures are different.The jumping patterns of pygmy mole crickets are quite different from others,The jumping characteristics of pygmy mole crickets are as follows: 1.The hind tibia of pygmy mole crickets does not contact with the base before jumping;2.The rotation speed of hind tibia and the extension speed of femur-tibia joint presents the patterns of “Sharp increase-sharp decrease-gradually increasing”;3.The body of pygmy mole crickets rotates after entering the middle stage of takeoff,and the rotation speed increases gradually;4.The change range of the hind femur-body joint angle is small during take-off;5.The role of tarsus appears largely to have been supplanted by the long apical spurs,particularly in jumping.The long apical spurs will point directly forwards.The long apical spurs of pygmy mole crickets does not contact with the base before jumping,and the tips of the long apical spurs are finally out of contact with the base at the end of the take-off stage;6.Once airborne the body rotates backwards and rises;The ratio of the characteristic structure of pygmy mole cricket to the body length was measured and counted.According to the movement regular pattern of the pygmy mole cricket in the take-off phase and the characteristic structure parameters of the pygmy mole cricket,the link structure of the pygmy mole cricket take-off model is abstracted and simplified into a plane mechanism.The D-H parameter method is used to establish the motion equation of the characteristic structure and calculate the motion trajectory of each characteristic point.The obtained trajectory has a high degree of agreement with the actual take-off trajectory.