We found that protein feeding and deprivation affected silk mechanics differently among the five species examined (see Supporting Information, S3 Table). Argiope keyserlingi’s silk was more extensible when protein deprived than when protein fed. On the other hand Eriophora transmarina’s silk was less extensible when protein fed (Supplementary Material, S3A and S3B Table). Both Nephila plumipes’ and Phonognatha graeffei’s MA silks were stronger and tougher when they were protein deprived (Supporting Information, S3D and S3E Table). Wherein we found neither protein feeding nor deprivation to effect the mechanical properties of Latrodectus hasselti’s silk (Supporting Information, S3C Table). Comparisons of the silk thread widths across treatments found a significant difference for A. keyserlingi only (means ± SE: protein deprived spiders = 3.39 ± 0.18 μm, protein fed spiders = 2.17 ± 0.15 μm, Supporting Information, S3A Table), thus thread width differences across treatments were not responsible for any of the variations silk mechanical properties found across the five species.