Skip over navigation
Reference Center
Encyclopedia
Dictionary
Thesaurus

Sponsored Links

More Sponsored Links For:

spider
Columbia Encyclopedia entry: spider
Spider, organism, mostly terrestrial, of the class Arachnida, order Araneae, with four pairs of legs and a two-part body consisting of a cephalothorax, or prosoma, and an unsegmented abdomen, or opisthosoma. The cephalothorax is covered by a shield, or carapace, and bears eight simple eyes. On the underside of the head (the cephalic part of the cephalothorax) are two pairs of appendages, the anterior pair called chelicerae and the second pair pedipalps, with which the spider captures and paralyzes its prey, injecting into it venom produced in the poison glands. The spider then liquefies the tissues of the prey with a digestive fluid and sucks this broth into its stomach where it may be stored in a digestive gland. Breathing is by means of tracheae (air tubes) or book lungs, or both. Arachnid book lungs are similar to the gill books of horseshoe crabs but are internal and adapted to a terrestrial habitat. Three pairs of spinnerets toward the tip of the abdomen produce protein-containing fluids that harden as they are drawn out to form silk threads. Several kinds of silk glands and spinnerets produce different kinds of silk used variously for constructing cocoons or egg sacs, spinning webs, and binding prey; other light strands are spun out for ballooning, or floating, the spiders, especially young ones, long distances on air currents. Spider silk is used for the cross hairs in certain optical instruments. Spiders live chiefly on insects and other arthropods; some large spiders ensnare and kill small snakes, birds, and mammals. Many are cannibalistic; the female may eat the male when courtship and mating are completed. Young, growing spiders can regenerate missing legs and parts of legs. Several species of spiders have bites that are exceptionally painful, or even dangerous to humans. Species of black widow spiders, which are found in the warmer parts of the world including the United States and S Canada, have a virulent neurotoxic venom. The bite venom of the brown recluse spider of SE and S central United States decomposes tissue, resulting in slow healing and sometimes leaving a sunken scar as large as a quarter. Among the more interesting spiders are the tarantula; its relative the trap-door spider, which ambushes its prey from a silk-lined burrow covered by a hinged lid; the orb weavers, which spin beautiful circular webs; and the crab spider, jumping spider, and wolf spider, named for their habits. Spiders are classified in the phylum Arthropoda, class Arachnida, order Araneae.

See B. J. Kaston, How to Know the Spiders (3d ed. 1978); R. F. Foelix, Biology of Spiders (1982); The Audubon Society Field Guide to North American Insects and Spiders (1992).

The Columbia Encyclopedia. Copyright © 2001-09 Columbia University Press. All rights reserved.

Wikipedia search results for: Spider
From Wikipedia, the free encyclopedia
Spiders are air-breathing chelicerate arthropods that have eight legs, and chelicerae modified into fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms. Sebastin PA & KV Peter. Spiders of India. Universities Press. ISBN 9788173716416 Spiders are found world-wide on every continent except for Antarctica, and have become established in nearly every ecological niche with the exception of air and sea colonization. As of 2008, approximately 40,000 spider species, and 109 families have been recorded by taxonomists; however, there has been confusion within...more »
Columbia Encyclopedia search results: spider
Results 1 - 10  of 46
  • trap-door spider

    Trap-door spider, spider of the same family as the native American tarantula. Trap-door spiders dig burrows, which they line with silk and protect by constructing one or two circular, hinged t...

  • sea spider

    Sea spider, common name for members of the class Pycnogonida, long-legged, rather spiderlike organisms of the phylum Chelicerata, widely distributed in marine waters. Most are tiny, from 1 to ...

  • brown recluse spider

    Brown recluse spider or violin spider, poisonous nocturnal spider, Loxoceles reclusa, most common in the SE and S central United States. Adults are 3/8 in. (10 mm) long and are light brown wit...

  • bookworm

    Bookworm, popular name for the larvae of several beetles that bore through books, e.g., the drugstore, spider, and deathwatch beetles.

  • tarantula

    Tarantula, name applied chiefly to several species of the large, hairy spiders of the families Theraphosidae and Dipluridae of North and South America. The body of a tarantula may be as much a...

  • black widow

    Black widow, poisonous spider of the genus Latrodectus, found throughout North and South America and common in the SW United States. The name derives from the fact that the female, like those ...

  • Arachne

    Arachne, in Greek mythology, a Lydian woman who challenged Athena to a trial of skill in weaving. When Arachne won, the goddess forced Arachne to hang herself. Athena then turned Arachne into ...

  • Chelicerata

    Chelicerata, phylum of the living horseshoe crabs (class Merostomata), the arachnids (class Arachnida), and the sea spiders (class Pycnogonida). Chelicerates are characterized by the absence o...

  • book lung

    Book lung, terrestrial respiratory organ characteristic of arachnids such as scorpions and primitive spiders. Each book lung consists of hollow flat plates. Air bathes the outer surface of the...

  • arachnid

    Arachnid, mainly terrestrial arthropod of the class Arachnida, including the spider, scorpion, mite and tick, harvestman (daddy longlegs), and a few minor groups. The body is divided into a ce...

Sponsored Links

More Sponsored Links For:

spider
1 2 3 4 5 Next

Related Encyclopedia Matches

Toggle Results

Video Results

powered by Truveo
more video »
Toggle Results

Reference Center To Go

Get Dictionary at your fingertips!

Download the Toolbar Now
About This Page | Browse Directory | Tell Us What You Think
© 2009 ReferenceCenter.com. All Rights Reserved.