Insect legs have attracted broad attention due to their complexity and critical functions including crawling,jumping,capturing,excavating and even perceiving,all of which are highly dependent on their morphology and microstructure.The relation between the function and structure of insect legs can provide valuable insights for bionic engineering and the development of new materials.As an excellent predator in the insect world,the praying mantis has a pair of powerful tools,two sharp and strong forelegs.The shape,microstructure and material of the foreleg of praying mantis play critical roles in capturing the prey,but their functional importance is not fully understood.Herein,the morphology,microstructure and nanomechanical properties of praying mantis forelegs(Mantis religiosa Linnaeus)have been investigated by CAD profiling,Matlab fitting,scanning electron microscopy and nanoindenter measurement.It has been found that the profiles of apical claw are same in shape and comparable in size,showing an exponential fitted curve,and the shape of the profiles is not closely related to the size of forelegs.The microstructure of the cuticle on femur and tibia is squamous and the surface of spines on these two parts has arris.The Youngs modulus and hardness of the femur cuticle,tibia cuticle and the apical claw show variations,which are in line with the observed microstructure.The analysis suggested that the foreleg shape of the praying mantis is critical for the preying action,and the dense and well-aligned microstructure offer excellent mechanical properties to the tibia and femur.It is conceivable that different microstructures caused different mechanical properties and the mechanical performance of foreleg surface is further enhanced by its shape,thus,the shape and microstructure of foreleg in praying mantis well accomplish the pray action and afford remarkable physical properties to the powerful capture tool: tibia and femur.In general,this analysis proved that shape and material are inseparable,and only a shape optimized for a material could lead to an efficient design in bionic engineering,and vise versa.Thus it has been demonstrated that the prey function of praying mantis is fitted and enabled by the synergy of morphology,microstructure and mechanical properties of the tibia and femur.The insight gained is expected to provide inspiration to the design of new bionic highperformance materials and bionic functional structures.