书城外语英国学生科学读本
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第74章 聪明的蜘蛛

1.You may have seen men setting nets in the sea,or in a river,to catch fish.Let me tell you about the little animals that are always setting nets in your house and in your garden in much the same way.These animals are called spiders,and they use their nets or webs to catch flies and other insects.

2.The spider itself is not an insect.An insect has only six legs,while the spider has eight.Theinsect‘s body is plainlydivided into three parts;but the spider has its body in two parts only,the head and the chest being united into one part,while the belly forms the other.Insects have four wings;spiders have no wings.

Spiders,again,have no feelers in front oftheir heads,as insects have.GARDEN SPIDER(园蛛)HEAD OF SPIDER(蜘蛛的头部)3.An insect lays an egg,which changes first into a grub or cater-pillar,then into a pupa or chrysalis,and lastly into an insect.The spider also lays eggs,but each egg produces a perfect little baby spider.The perfect insect never grows bigger;but the little spiders grow so fast for a time that they haveto throw off their leathery①skins,and grow larger ones every few weeks.

4.The web of the spider is made of silk.This silk is formed inside the spider’s body as a gummy fluid.It is squeezed out of several holes at the end of the spider‘s body,and the moment it comes out into the air it hardens and forms adelicate②thread.The spider twists several of thesefine threads together to form one strong line.

5.Try to find a spider’s web on a bush or on theUNDER SIDE OF BODY(蜘蛛的腹面)grass in your garden,and look very closely at it.The spider makesthe outside lines of the web first.Then it forms the lines which extend like the spokes③of a wheel from the centre of the net to the edges.All these lines of the web are made of smooth elastic④threads of silk.

6.Lastly,it starts from the centre of the web and fastens a slender line across the others,SPIDER‘S WEB(蜘蛛网)①Leathery,tough like leather.

②Delicate,tender;easily broken or hurt.

③Spokes,the bars of a wheel stretching from the rim to the centre.

④Elastic,springy;able to return quickly to its original shape.

going round and round in a spiral①.This spiral or cross thread is covered by the spider with thousands of tiny drops of a very sticky substance.Then the spider goes to one corner of the net and waits.

7.Soon an insect-perhaps a common fly-rushes in its flight against the web,and is caught by the drops of sticky stuff.Out comes the spider,runs to the fly,and rolls a band of its gummy silk around it.Then the spider gives the fly a bite,to kill it,or carries it away to one corner of the web till it is wanted for food.

8.The spider’s jaws are grooved②,and in its head are sometiny poison-bags.When the spider bites,some of the poison runs down the grooves,and so enters the body of the insect which is bitten.After this the insect is unable to move or to fly away.

TRAP-DOOR SPIDER(活门蜘蛛即)

9.There are many spiders which in habits and appearance are quite different from the garden spider.Some of them have their nests in little holes in the ground,and make little trap-doors③to close them.Others live under water,and carry down little bubbles of air to breathe in their homes.

①Spiral,screw-like fashion.

②Grooved,hollowed out.

③Trap-door,a door or roof which shuts with a spring like a trap.

SUMMARY

The spider differs from an insect in having eight legs,a body divided into two parts only,no wings,and no feelers.Each egg of the spider produces a little spider,which does not pass through any changes like the insect.The spider grows very fast,but the perfect insect never grows.The spider‘s web is made of silk formed by the hardening of a gummy juice squeezed out of the spider’s body.Flies and other insects are caught by the sticky cross threads of the web.From spiders‘webs silk gloves and stockings have been made.The spider has grooved jaws,down which poison runs from small bags in its head when it bites.

【中文阅读】

1.你可能看到过有人在海面或河面上撒网捕鱼。现在,我来跟你说一说,有一种动物经常在你的家里、花园里结网捕食。这种动物叫做蜘蛛①,它们利用自己的网来捕食苍蝇与其他昆虫。

2.蜘蛛并不属于昆虫,因为昆虫只有六条腿,但蜘蛛有八条;昆虫的身体很明显地分为三个部分,但是蜘蛛则只有两个部分:它们的头部与胸部连接在一起,腹部则构成另外一部分。昆虫长有四只翅膀;而蜘蛛没有翅膀。蜘蛛的头部也没有昆虫那样的触角②。

3.昆虫产卵,然后孵化为幼虫或毛虫,再变成蛹并最终生长为昆虫。蜘蛛同样产卵,但是每一颗卵都能够孵化出结构完整的小蜘蛛。昆虫成虫身体不会生长变大,但是小蜘蛛的生长速度却快,经过一段时间之后就要蜕皮,每过几周时间身体就会长大一些。

4.蜘蛛网由细丝构成,这些细丝来自其体内的粘稠液体。蜘蛛通过身体末端的几个小孔将这些液体排出,它们一遇到空气就会立刻凝固并形成细线。蜘蛛将这些细线缠绕在一起,形成一条结实的绳索③。

5.走到花园中,试试看能不能在树丛或草地上找到一张蜘蛛网,然后仔细观察。蜘蛛首先编织的就是外围的蛛丝,然后从中间往边缘的方向搭建轮辐般的蛛丝。这些蛛网全部由极富弹性的柔顺丝线组成。

6.最后,蜘蛛从蛛网中心绕上一圈又一圈的细丝,它们构成彼此交叉的横丝。蜘蛛又在这些螺旋或交叉横丝上涂抹了数以千计的非常粘稠的物质。然后,它便躲在一个角落里,耐心等待。

7.很快,有只昆虫--可能就是一只普通点的苍蝇--在飞行中撞上了这张蛛网,然后便被粘稠物质抓个正着。这时,蜘蛛就会爬出来,扑向苍蝇,用粘稠的细丝将其团团围住。然后,蜘蛛就会在苍蝇身上咬上一口,把它杀死或者把它搬运到蛛网的某个角落,等到想吃的时候再慢慢品尝。

8.蜘蛛的牙齿长有沟槽,头部则生有几个很小的毒囊。当蜘蛛咬下猎物时,一部分毒液顺着凹槽流入猎物。这时候,被咬的昆虫动不了也飞不走了。

9.蜘蛛的种类很多,它们的习性、外貌与我们在花园中见到的蜘蛛相差很大。有些蜘蛛在地下的洞中栖身,在洞口造出一个既能遮挡地洞又能捕获猎物的活门。还有些蜘蛛生活在水中,它们能够将小气泡带入水中,用于在自己的巢穴中呼吸④。

译注

①蜘蛛属于节肢动物门-蛛形纲-蜘蛛目,大概3亿年前就出现在地球上了。目前大约有4万种,中国有大约2000多种。有意思的是,大部分节肢动物的腿都有肌肉,但蜘蛛腿却没有肌肉,而是用液压行动的。

②其实严格地说,蜘蛛除了4对步足也就是8条腿之外,还有前面的1对“螯肢”和1对“触肢”,所以一共是6对附肢;触肢的作用相当于触角,其实昆虫的触角也是附肢特化成的。“昆虫有触角,蜘蛛没有触角”的说法不太准确。

③蜘蛛丝:读者可能都对科幻电影《蜘蛛侠》里彼得·帕克发射蜘蛛丝的场面记忆犹新吧?蜘蛛丝是一种蛋白质,具有极好的韧性和强度,是仿生学研究的重要对象之一。

④土蜘蛛和水蜘蛛:生活在地下的蜘蛛俗称“活门蜘蛛”,学名很难写,叫““(),那个活门是用土、植物和丝混合制成的。水蜘蛛也叫银蛛,是唯一一种完全生活在水下的蜘蛛,用身上的绒毛携带的气泡来呼吸,住在蛛丝和气泡构成的巢中,偶尔游到水面上补充自己的”氧气瓶“和”住所“的空气。

A PANE OF GLASS