近日，據(jù)美國國家地理網(wǎng)站報道，美國科學家進行的一項新研究發(fā)現(xiàn)，體型微小蜘蛛的擁有相對于它們的體型來說巨大的大腦,。這種巨腦可能解釋了體型微小的蜘蛛的織網(wǎng)能力為何與體型更大的蜘蛛不相上下。相關論文刊登在11月出版的《節(jié)肢動物結構與發(fā)育》（Arthropod Structure and Development）雜志上,。
研究過程中,，史密森尼熱帶研究所研究員比爾-伊伯哈德率領的團隊對來自6個結網(wǎng)蜘蛛家族的9個種群進行了分析,。研究人員發(fā)現(xiàn),，蜘蛛的體型越小，相對于體型的大腦體積越大,。一些蜘蛛種群的中樞神經(jīng)系統(tǒng)所占據(jù)的空間達到整個身體的近80%,，有時甚至會溢入腿部。
圓蛛Leucauge mariana等一些蜘蛛的幼仔因大腦巨大身體發(fā)生膨脹,，這種現(xiàn)象直到發(fā)育成熟后才消失,。伊伯哈德表示大腦占據(jù)大部分體內空間似乎對其他器官帶來問題。對于這一現(xiàn)象,，科學家并沒有進行深入研究。巨大的大腦同樣影響了蜘蛛綱動物的外形?？茖W家在研究中發(fā)現(xiàn),，成年跳蛛Phidippus clarus的消化系統(tǒng)位于頭胸部,。但在年輕個體身上,，所有這些空間都被大腦占據(jù)，幼仔的消化系統(tǒng)并不成熟,。巨腦將對蜘蛛的發(fā)育產(chǎn)生影響仍是一個未知數(shù)。
Eberhard在描述這項研究的文章中指出,，據(jù)推測,，較大的大腦是織網(wǎng)所必須的?？椌W(wǎng)是一種更為復雜的行為。所謂的偷竊寄生蜘蛛并不具有織網(wǎng)能力,，靠偷竊其他蜘蛛的獵物為生,，但沒有任何跡象顯示，它們擁有相對較小的大腦,。偷竊需要在悄無聲息中進行,，要求偷竊寄生蜘蛛具備一定程度的智商,，這也就解釋了這個竊賊的大腦為何與結網(wǎng)蜘蛛不相上下,。（生物谷Bioon.com）
doi:10.1016/j.asd.2011.07.002
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The allometry of CNS size and consequences of miniaturization in orb-weaving and cleptoparasitic spiders
Rosannette Quesada, Emilia Triana, Gloria Vargas, John K. Douglass, Marc A. Seid, Jeremy E. Nivena, William G. Eberhard, William T. Wcislo
Allometric studies of the gross neuroanatomy of adults from nine species of spiders from six web-weaving families (Orbicularia), and nymphs from six of these species, show that very small spiders resemble other small animals in having disproportionately larger central nervous systems (CNSs) relative to body mass when compared with large-bodied forms. Small spiderlings and minute adult spiders have similar relative CNS volumes. The relatively large CNS of a very small spider occupies up to 78% of the cephalothorax volume. The CNSs of very small spiders extend into their coxae, occupying as much as 26% of the profile area of the coxae of an Anapisona simoni spiderling (body mass < 0.005 mg). Such modifications occur both in species with minute adults, and in tiny spiderlings of species with large-bodied adults. In at least one such species, Leucauge mariana, the CNS of the spiderling extends into a prominent ventral bulge of the sternum. Tiny spiders also have reduced neuronal cell body diameters. The adults of nearly all orbicularian spiders weave prey capture webs, as do the spiderlings, beginning with second instar nymphs. Comparable allometric relations occur in adults of both orb-weaving and cleptoparasitic species, indicating that this behavioral difference is not reflected in differences in gross CNS allometry.
