谁都跑得比你快——对于一只食肉蜗牛来说，没什么比这更让人泄气的了。
为了让这顿饭能待着不动，鸡心螺—— 一种大型海洋软体动物（如上图）——进化出满嘴中空的鱼叉形牙齿，其中填满了毒液。当这些毒液被喷到猎物身上后会使后者麻痹，并最终被鸡心螺拖入口中。
然而其毒腺本身意大利面条式的罕见结构却在一个多世纪的时间里让科学家感到困惑不解。
为了重温由一名19世纪的法国博物学家所进行的奇妙观察——他相信毒腺由食道剥离的组织进化而来，一名研究人员切开了一些小鸡心螺，并研究了它们的喉咙解剖学构造。
这名研究人员发现在食道中存在一种非常细微的结构变化，它是如此之小以至于不足以破坏蜗牛祖传的食草习性，然而当鸡心螺长大后便会形成一个毒腺。
研究人员在5月17日的英国《皇家学会学报B》网络版上报告了这一发现，并指出，这种平稳过渡或许解释了这些蜗牛如何进化出它们复杂的“兵工厂”，以及在极短的进化时间表内变为肉食性的。（生物谷Bioon.com）
生物谷推荐原文：
Proceedings of the Royal Society B: Biological Sciences DOI： 10.1098/rspb.2011.0501
Developmental modularity and phenotypic novelty within a biphasic life cycle: morphogenesis of a cone snail venom gland
Page, Louise R.
The venom gland of predatory cone snails (Conus spp.), which secretes neurotoxic peptides that rapidly immobilize prey, is a proposed key innovation for facilitating theextraordinary feeding behaviour of these gastropod molluscs. Nevertheless, the unusual morphology of this gland has generatedcontroversy about its evolutionary origin and possible homologues in other gastropods. I cultured feeding larvae of Conus lividus and cut serial histological sections through the developing foregut during larval and metamorphic stages to examine the developmentof the venom gland. Results support the hypothesis of homology between the venom gland and the mid-oesophageal gland of othergastropods. They also suggest that the mid-region of the gastropod foregut, like the anterior region, is divisible into dorsaland ventral developmental modules that have different morphological, functional and ontogenetic fates. In larvae of C. lividus, the ventral module of the middle foregut transformed into the anatomically novel venom gland of the post-metamorphic stageby rapidly pinching-off from the main dorsal channel of the mid-oesophagus, an epithelial remodelling process that may besimilar to other cases where epithelial tubes and vesicles arise from a pre-existing epithelial sheet. The developmental remodellingmechanism could have facilitated an abrupt evolutionary transition to the derived morphology of this important gastropod feedinginnovation.
