誰都跑得比你快——對于一只食肉蝸牛來說,，沒什么比這更讓人泄氣的了,。
為了讓這頓飯能待著不動，雞心螺—— 一種大型海洋軟體動物（如上圖）——進(jìn)化出滿嘴中空的魚叉形牙齒,，其中填滿了毒液,。當(dāng)這些毒液被噴到獵物身上后會使后者麻痹，并最終被雞心螺拖入口中,。
然而其毒腺本身意大利面條式的罕見結(jié)構(gòu)卻在一個多世紀(jì)的時間里讓科學(xué)家感到困惑不解,。
為了重溫由一名19世紀(jì)的法國博物學(xué)家所進(jìn)行的奇妙觀察——他相信毒腺由食道剝離的組織進(jìn)化而來，一名研究人員切開了一些小雞心螺，并研究了它們的喉嚨解剖學(xué)構(gòu)造,。
這名研究人員發(fā)現(xiàn)在食道中存在一種非常細(xì)微的結(jié)構(gòu)變化,，它是如此之小以至于不足以破壞蝸牛祖?zhèn)鞯氖巢萘?xí)性,，然而當(dāng)雞心螺長大后便會形成一個毒腺,。
研究人員在5月17日的英國《皇家學(xué)會學(xué)報B》網(wǎng)絡(luò)版上報告了這一發(fā)現(xiàn)，并指出,，這種平穩(wěn)過渡或許解釋了這些蝸牛如何進(jìn)化出它們復(fù)雜的“兵工廠”,，以及在極短的進(jìn)化時間表內(nèi)變?yōu)槿馐承缘摹＃ㄉ锕菳ioon.com）
生物谷推薦原文：
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.
