对于盗蛛而言，没有什么比送出咀嚼过的食物更能表达爱意了。在这种欧洲蛛形纲动物的某些种群里，雄性蜘蛛必须把捕获的昆虫用蛛丝缠绕起来，作为礼物送给雌性蜘蛛，否则雌性蜘蛛不会同意做它的伴侣。
雄性蜘蛛在求爱期间随身携带数个小小的昆虫包，但目前科学家们尚不清楚这些多余的“行李”在多大程度上影响雄性蜘蛛的奔跑和战斗能力。待解的问题还有，这些八条腿的动物是否也会欺骗：把一些不能吃的东西或者是已经干透的昆虫尸体一起放进它们的礼物包中，使礼物看起来更大。
研究者们在野外观察了58只雄性盗蛛之后，把相关研究结果刊发在这个月的《动物行为》（Animal Behaviour）杂志网络版上，其中涉及了上述两个问题。
在这58只雄性蜘蛛里，23只携带了礼物包，所有的礼物包中都有新捕获的昆虫的肢体。在另外一些实验室观察中，科学家们发现，当雄性蜘蛛互相打斗时，带礼物者显然并没有因为礼物的妨碍而输给不带礼物者，尽管有一些更强壮的、携带或不携带礼物的雄性蜘蛛会从弱一些的同类那里偷走礼物包。实验室观察还发现，礼物包的确会影响雄性蜘蛛的奔跑能力。计时测验结果显示，携带礼物的蜘蛛奔跑速度比同样大小的、不携带礼物的雄性蜘蛛慢了42%。这一数据首次显示了对于昆虫和蜘蛛来说，携带礼物的代价是什么。
研究人员还推测，这种为爱甘当苦力的行为能够显示雄性蜘蛛获得并保有食物的能力。（生物谷Bioon.com）
doi:10.1016/j.anbehav.2012.03.007
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Gift carrying in the spider Pisaura mirabilis: nuptial gift contents in nature and effects on male running speed and fighting success
Pavol Prokop, Michael R. Maxwel
Males of the spider Pisaura mirabilis offer prey items as nuptial gifts to females. While gift giving in this species has received attention in captivity, the ecological context of these gifts remains largely unknown. First, we examine the occurrence of gift carrying by males in nature. Field data reveal that gift-carrying males are frequent in nature (40% of captured males), and that all gifts contain fresh arthropod prey. Gift mass was positively correlated with the longest diameter of the gift. Thus, males do not appear to ‘cheat’ by inflating their gifts with inedible items, air or loosely wrapped silk. Second, we examine two ecological costs to gift-carrying males: the effects of gifts on male running speed and male fighting success. Gift carrying reduced male running speed, but did not affect male fighting success in male–male contests. The former result is the first demonstration of a transportation cost associated with gift carrying in an arthropod.
