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  3. Spiders Spiders can be distinguished from other Arachnids because the prosoma (combined head and thorax) is only separated f

Spiders Spiders can be distinguished from other Arachnids because the prosoma (combined head and thorax) is only separated f

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问题                             Spiders
    Spiders can be distinguished from other Arachnids because the prosoma (combined head and thorax) is only separated from the opisthosoma (abdomen) by a narrow waist, in other Arachnids the whole body appears to be much more of a single unit. All spiders produce silk, but only some construct webs to catch their homes and to protect their eggs.
    All spiders possess poison glands but very few of them are dangerous to humans, of the 600+ species in Britain only 12 (at least one of these is a recent human assisted colonist) are strong enough to pierce the human skin, and apart from allergies, none are more dangerous than a common wasp. Most spiders have 8 eyes (though some have 6, 4, 2 or 0), as well as 8 legs. (by the way if you count the claws as separate leg section [which you shouldn’t really] then their legs have 8 parts as well [coxa, trochanter, femur, patella, tibia, tarsus, metatarus, claws]) There are more than 32000 known species of spider in the world. No human being has ever been officially recorder as having died as the result of a ’tarantula’ bite.
    All spiders are carnivorous and feed only on liquids, i.e. their preys natural juices and the breakdown products of external digestion (meaning they spit, exude or inject digestive juices onto/into their prey and suck up the resulting soup). So why not invite some to your next social do?
    What’s In a Name
    The word ’Arachnida’ comes from the Greek word ’Arachne’ who was the daughter of Idmon of Colophon in Lydia, a dyer by trade. Arachne herself was a weaver, the best in all the known world. However in a foolish moment she challenged Athena, the daughter of Zeus and goddess of, among other things, waving to a weaving competition. Arachne wove so perfect a cloth that she tore it to shreds. Arachne became depressed after this and in the end she hung herself. Athena stirred to remorse at the knowledge of what her anger had wrought turned the rope Arachne had used to hang herself into a web and Arachne herself into a spider so that the beauty of her spinning should not be lost to the world ever again.
    The Great Household Spider Safari
    There are just over six hundred different sorts of spider in the British Isles. But of these only ’a handful are commonly found in houses. At the front of the head are a pair of what appear to be small legs. These are called palps and are used to guide food to the spider’s mouth. The front of the head also has a group of six or eight eyes. On the underside of the body at the rear, are four or six small conical bumps or cylinders. There are the spinnerets from which the spider produces the silk to make its webs.
    Telling male and female spiders apart is easily done by looking at their palps. Males have swollen ends to their palps which makes them look as if they are wearing boxing gloves, these are often strange shapes if looked at with a hand lens. Females have normal looking palps that are not swollen at the ends.
    The largest spider is the Goliath spider, the female of which grows to reach a leg span of ten inches, The largest spider in Britain is the Cardinal spider which is a close cousin of Tim Tegenaria. Females can achieve a leg span of four and a half inches. It is known as the Cardinal spider as it was common in Hampton Court when Cardinal Wolsey lived there. The sight of these long legged spiders wandering around the palace at night used to frighten him. So far 32000 different kinds of spider have been discovered from all over the world. Britain has 630 different kinds of spider of which 250 are tiny Money spiders. The smallest of which has a body less than one millimeter long.
Telling male and female spiders apart is easily done by ______.
选项
答案looking at their palps
解析 该题定位在倒数第二段的首句。
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