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( Spiders)
Mesothelae
Mygalomorphae
Araneomorphae
&_160;See table of families A vegetarian species was described in 2007, but all others are predators, mostly preying on insects and on other spiders, but a few large species also take birds and lizards. However the young of many spiders supplement their diet with nectar and there is statistical evidence that even adults supplement theirs with pollen. Spiders' chelicerae are modified into fangs, which in most cases can inject venom into prey. While the venom of relatively few species is dangerous to humans, scientists are now researching the use of spider venoms in medicine and as non-polluting pesticides. Spiders capture prey by trapping it in sticky webs, waiting in ambush for it or running it down. Species that use webs or ambush tactics are extremely sensitive to vibrations in the air, ground and silk threads that they use as tripwires, while the active hunters have eyesight up to ten times as acute as that of dragonflies. Some active hunters also use different tactics for different prey, and show signs of intelligence by trying a variety of tactics against difficult prey and by learning very quickly what tactics to adopt against unfamiliar prey. Others have modified bodies and behavior patterns that enable them to mimic ants on which they prey. Spider's webs vary widely in size, shape and the amount of sticky thread used. It now appears that the spiral orb web may be one of the earliest forms. Orb-web spiders, although well-known and the most extensively studied, are a minority of spider species and spiders that produce other types of web are more abundant, possibly because their tangled webs present greater obstacles to predatory wasps. In males spiders the pedipalps (appendages just below / behind the mouth) are modified as syringes that inject sperm into females' genitalia. To avoid being eaten before they can mate, male spiders identify themselves by a variety of complex courtship rituals. Males of most species survive a few matings, limited mainly by their short life spans, and in a few species males live for a while in their mates' webs. However males of a few species impale themselves on the females' fangs while mating, perhaps because ensuring that their mates are well-fed increases the likely number of offspring. Female spiders weave silk egg-cases, each of which may contain hundreds of eggs; the spiders then hatch as apparently miniature adults, although most are incapable of feeding until after their first molt. Females of many species care for their young, for example by carrying them around or by sharing food with them. A minority of species are social, building communal webs that may house anywhere from a few to 50,000 individuals. Social behavior ranges from precarious toleration, as in the aggressive widow spiders, to co-operative hunting and food-sharing. Although most spiders live for at most two years, tarantulas and other mygalomorph spiders can live up to 25&_160; years in captivity. Spider-like arachnids with silk-producing spigots appear in the Devonian period about 386 million years ago, but these animals apparently lacked spinnerets. True spiders have been found in Carboniferous rocks from 318&_160;to&_160;299 million years ago, and are very similar to the most primitive surviving order, the Mesothelae. The main groups of modern spiders, Mygalomorphae and Araneomorphae, first appear in the Triassic period, before 200 million years ago. After 130 million years ago fossil amber preserves details of spiders' anatomy and behavior, including mating, killing prey, producing silk and possibly caring for their young. In a few cases amber has preserved spiders' egg sacs and webs, occasionally with prey attached.
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Spiders Subcategories
Spiders Articles
Easily Prevail Over A Silly Fear Of Spiders - Arachnophobia by Alan Densky
programs available for treating phobias. Most utilize traditional forms of hypnosis that rely on the use of post-hypnotic suggestions with very exact wording to work against fears. In this day and age, post-hypnotic suggestions rarely work becaus...
Relief for Phobias by Phone by Michelle Beaudry
You've Had Enough Pain and Suffering You're tired of being afraid, and you're ready to change. Phobias limit your life at every turn, and you're all done feeling limited. You need a plan to make the change. Read on, my friend, and let me help you...
Spiders in Your Legs? Here's How to Get Rid of Them by Ismael D. Tabije
As I was searching for more information on varicose veins’ cure, I sat on the swivel chair in front of the PC in a relaxed but poised position: upright with my right leg over my left leg. What I thought of as a comfortable sitting position coul...
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