近日，据美国国家地理网站报道，美国科学家进行的一项新研究发现，体型微小蜘蛛的拥有相对于它们的体型来说巨大的大脑。这种巨脑可能解释了体型微小的蜘蛛的织网能力为何与体型更大的蜘蛛不相上下。相关论文刊登在11月出版的《节肢动物结构与发育》（Arthropod Structure and Development）杂志上。
研究过程中，史密森尼热带研究所研究员比尔-伊伯哈德率领的团队对来自6个结网蜘蛛家族的9个种群进行了分析。研究人员发现，蜘蛛的体型越小，相对于体型的大脑体积越大。一些蜘蛛种群的中枢神经系统所占据的空间达到整个身体的近80%，有时甚至会溢入腿部。
圆蛛Leucauge mariana等一些蜘蛛的幼仔因大脑巨大身体发生膨胀，这种现象直到发育成熟后才消失。伊伯哈德表示大脑占据大部分体内空间似乎对其他器官带来问题。对于这一现象，科学家并没有进行深入研究。巨大的大脑同样影响了蜘蛛纲动物的外形。科学家在研究中发现，成年跳蛛Phidippus clarus的消化系统位于头胸部。但在年轻个体身上，所有这些空间都被大脑占据，幼仔的消化系统并不成熟。巨脑将对蜘蛛的发育产生影响仍是一个未知数。
Eberhard在描述这项研究的文章中指出，据推测，较大的大脑是织网所必须的。织网是一种更为复杂的行为。所谓的偷窃寄生蜘蛛并不具有织网能力，靠偷窃其他蜘蛛的猎物为生，但没有任何迹象显示，它们拥有相对较小的大脑。偷窃需要在悄无声息中进行，要求偷窃寄生蜘蛛具备一定程度的智商，这也就解释了这个窃贼的大脑为何与结网蜘蛛不相上下。（生物谷Bioon.com）
doi:10.1016/j.asd.2011.07.002
PMC:
PMID:
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.
