Lifeline for Immature Spiders

It is important to measure the degree of safety since a spider s life depends on the draglines. 

in order to consider the draglines from the structural point of view, it is important to estimate the value (S/W) of the cross section area S of the dragline per spider s weight W. 

A drastic change in the safety coefficient from 3 to 2 was observed at about 50 mg of N. clavata spiders in summer when divergence of sex and rapid increase in the female spider s weight after the final ecdysis occurred. The spider s weight of about 50 mg corresponds to the weight at the stage when spiders grow from immature to mature in summer. 

It was found that the safety coefficient of about 3 is based on relatively thick draglines for young or immature spiders while the safety coefficient of about 2 is most efficient for mature spiders from the viewpoint of energy consumption and safety. 

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