Scanning electron micrograph of ivory ornamental spider silk (Poecilotheria subfusca). Silk is commonly used by tarantulas for basic functions such as protecting eggs or lining burrows, varying greatly in its appearance from the complex and elaborate webs spun by other spiders, such as the orb weavers. While tarantula silks may be simple in their nature great interest has been generated in determining whether the variation seen in the silk types produced by the 900 mygalomorph species translates to a difference in their material properties. Magnification: 500x. Silk strands are approximately 2 micrometers thick. Supplied by Lauren Holden, courtesy of Wellcome Images.