INTRODUCTION

Spiders are unique in the animal world due to the use of silk throughout their life span and a nearly total dependence on silk for their evolutionary success (Lucas, 1964; Vollrath, 1992). There were periods of fairly intense study of spider silk prior to World War II and in the late 1950s. However, progress was relatively meager, especially when compared with research on silkworm silk. Beginning in the 1970s, studies carried out in the laboratories of Work, Gosline, and Tillinghast reinvigorated interest in spider silk, with several papers describing their physical, mechanical, and chemical properties. These papers set the stage for the current advances in our understanding of these fibers.

BIOLOGICAL ASPECTS OF SPIDER SILK PRODUCTION

Typical spider webs are constructed from several different silks, each of which is produced in a separate gland. Non-orb web-weaving spiders produce fewer silks and use them differently in many cases. The non-orb weavers constitute the majority of spiders and include those species that do not make the usual orb-shaped web. The various silks produced by the orb web-weaving spiders, the glands that produce them, and the uses of the spiders for each silk are listed in Table 7.1.

Although each of the silk glands has its own distinctive shape and size, they are all functionally organized in a similar pattern. The majority of the gland serves as a reservoir of soluble silk protein that is synthesized in specialized cells at the distal end of the gland.