Mechanics and morphology of silk drawn from anesthetized spiders

CO2 and N-2 anesthetized Nephila spiders produced dragline silk with mechan ical properties that differed from control silk as a function of time under anesthesia. Silk from CO2 spiders had a significantly lower breaking strai n and breaking energy, significantly higher initial modulus, and marginally lower breaking stress. At the onset of anesthesia the silk diameter became highly variable. During deep anesthesia silk either became thinner or reta ined cross-section but fibrillated.