Tensile properties of A. atlas silk submerged in liq- uid media was previously reported [20]. It was reported that immersion in water greatly reduced the elastic modulus but immersion in ethanol increased the mod- ulus. Although A. atlas fibers have different amino acid composition compared to that of B. mori silk fibers, they have similar mechanical properties. However, the A. at- las fibers have considerably different mechanical prop- erties than spider silk although spider silk and A. atlas have similar amino acid composition [21]. It has also been suggested that the tensile failure mechanism of A. atlas fibers involves the pulling of micofibrils from the matrix, similar to that observed in composites [26]. The moisture regain of the A. atlas silk fibers was higher than that of the other silk fibers in Table 2. Overall, the tensile properties of the A. atlas fibers are similar to that of B. mori silk than the common wild silks