In this article we will discuss about the structure of spider with the help of a suitable diagram.
Spiders, like most arachnids, live on a completely liquid diet. All are predatory. The prey is bitten and often paralyzed by the chelicerae, and then enzymes from the mid-gut are poured out over the torn tissues to produce a partially digested broth.
The liquefied tissues of the prey are pumped into the stomach by the muscular pharynx, where digestion is completed and the juices absorbed. Arachnids respire by means of tracheae or book lungs, or both. Book lungs are a series of leaf like plates within a chitin-lined chamber into which air is drawn and expelled by muscular action.
On the posterior portion of the spider’s abdominal surface is a cluster of spinnerets, fingerlike organs from which a fluid protein exudes that polymerizes into silk as it is exposed to air.
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Silk is used not only for the variety of prey-snaring webs made by the different species but for a number of other purposes as well, such as a drop line, on which the spider can make a defensive dive, draglines for marking a course, gossamer threads for ballooning, hinges for trap doors, an egg case, lining for a burrow, the shroud of a victim, or a wrapping for an edible offering presented to the female of certain species by the courting male.
Most spiders can spin several kinds and thicknesses of silk. Webs are species-specific, and web-building is a genetically programmed behaviour.