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Web-spinning spiders cannot catch food by hunting because of their poor vision. Instead, they spin webs in the air to trap flying insects. The spider does not become caught in its own web, because when walking across the web it grasps the silk lines with a special hooked claw on each foot.
In its natural habitat each species builds its traps according to predetermined, inherited patterns. Whether the web is made by a newly-hatched spiderling or a full-grown spider, the design is the same. Only the size differs.
Tangled-web weavers spin the simplest type of web. It consists of a shapeless jumble of threads attached to a support, such as the corner of a ceiling. The cobwebs found in houses are tangled webs that have collected dust and dirt. Cellar spiders spin tangled webs in dark, empty parts of buildings. Comb-footed spiders spin a tangled web with a tightly woven sheet of silk in the middle. The sheet serves as an insect trap and as the spider's hideout. These spiders get their name from the comb of hairs on their fourth pair of legs, which is used to throw liquid silk over an insect and trap it. The black widow is a comb-footed spider.
left: web of a common house spider
Some spiders spin a tangled web containing a hackled band of dry and sticky silk. The ogre-faced stick spider spins a web that is made up largely of hackled bands. With its four rear legs, the spider hangs upside down from the dry silk; it holds the sticky web with its four front legs. When an insect flies near, the spider stretches the sticky web to several times its normal size and captures the insect.
right: an enlargement of the hackled band included in an ogre-faced stick spider's web
Sheet-web weavers weave flat sheets of silk between blades of grass or branches of shrubs or trees. They also spin a net of crisscrossed threads above the sheet web. When a flying insect hits the net, it bounces into the sheet web. The spider, which hangs upside down beneath the web, quickly runs to the insect and pulls it through the webbing. Some sheet-web weavers spin two separate sheets as a web. The spider hangs upside down under the top sheet. The sheet beneath the spider probably protects it from attack from below. Sheet webs last a long time because the spider repairs any damaged parts.
left: a sheet web
Orb weavers weave their round webs in open areas, often between tree branches or flower stems. Threads of dry silk extend from an orb web's center like the spokes of a wheel. Coiling lines of sticky silk connect the spokes, and serve as an insect trap. Some orb weavers lie in wait for their prey in the center of the web. Others attach a trap line to the center of the web. The spider hides in its nest near the web, and holds on to the trap line. When an insect lands in the web, the line vibrates. The spider darts out and captures the insect. Many orb weavers spin a new web every night. Others repair or replace damaged parts of their webs.
left: a typical orb web
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This page was last updated on July 14, 2017.