Ensemble of functions of biological life of tarantulas is connected with production of web. It is used for following purposes:
- arboreal species entwines in fissures of bark, forks of branches or amongs leafs of trees so-called "silken tubes" used as a retreats where`re they live – it is practically peculiar air «burrows»;
- most of terrestrial tarantulas plait an entry in burrow with the web for preventing a flood as well as for additional insulation from external world (this is important, for instance, during the molting process, when spider helpless practically);
- during his movements outside of burrows spider pull after itself silken track, to find quick way back;
- tarantulas is also lay with the web the room inside the burrow that prevents its fall and enlarges the living area;
- the web is used by many tarantulas for fastening a food objects;
- tarantula enwinds a web cradle for additional protection during a molting process;
- tarantula males spins a sperm-web, used as a vault for temporary store of sperm;
- also tarantulas were recognize a female`s burrow on chemical features of the web beside its entry;
- and, probably, one of the the most important moments in tarantula life is connected with producing the web by female for constructing a cocoon for eggs.
Other spiders use the web for more wider purposes, for example, spins hunting nets, but it is not characteristic for tarantulas that is also confirms an antiquity of their origin.
Spider web has mainly protein base and possesses the unique characteristics: it is surprisingly strong, light, for a long time does not decay under influence of surrounding ambience, nearly not a subject to be infected by microorganisms and fungi.
Aborigines of some countries use it for entwined a net for catching a small fishes and fabrics for clothes. The web is produced with silk-producing glands openning through microscopic channels in spinnerets (silk appendages), which is disposed on the end of tarantula abdomen.
Male tarantulas have silk-producing organs near their genital openings called epiandrous glands. These glands lead out to tiny, hardly observable spinneret channels in a crescent shape above the epigastric furrow called epiandrous fusillae. It is considered that it takes part in the process of male sperm-web producing.
And finally the recent scientists findings discover that tarantulas can produce the silk by means of the micro-glands on the end of the tarsi (Stanislav N. Gorb, Senta Niederegger, Cheryl Y. Hayashi, Adam P. Summers, Walter Vetsch, Paul Walther (2006) Silk-like secretion from tarantula feet. NATURE Journal, Vol. 443: 28) which gives a heavy spiders an additinal possibility to creep up the smooth surfaces.