Occidental College, Los Angeles, CA 90041-3314, USA.
J Exp Biol. 2010 Mar 1;213(5):673-82. doi: 10.1242/jeb.035550.
Cone snails use an extensile, tubular proboscis as a conduit to deliver a potent cocktail of bioactive venom peptides into their prey. Previous studies have focused mainly on understanding the venom's role in prey capture but successful prey capture requires both rapid physiological and biomechanical mechanisms. Conus catus, a fish-hunting species, uses a high-speed hydraulic mechanism to inject its hollow, spear-like radular tooth into prey. We take an integrated approach to investigating the biomechanics of this process by coupling kinematic studies with morphological analyses. Taking advantage of the opaque venom and translucent proboscis of a mollusc-hunting juvenile cone snail, Conus pennaceus, we have determined that a high-speed prey capture mechanism is not unique to cone species that hunt fish prey. Two morphological structures were found to play crucial roles in this process. A constriction of the lumen near the tip of the proboscis, composed of tall epithelial cells densely packed with microfilaments, impedes forward movement of the radular tooth prior to its propulsion. Proximal to the constriction, a muscular sphincter was found to regulate venom flow and pressurization in the proboscis. In C. pennaceus, the rapid appearance and flushing of venom within the proboscis during prey capture suggests a mechanism involving the delivery of a discrete quantity of venom. The interplay between these elements provides a unique and effective biomechanical injection system for the fast-acting cone snail venom peptides.
梭子蜗牛利用可伸展的管状喙作为导管，将强效的生物活性毒液肽混合物输送到猎物身上。以前的研究主要集中在了解毒液在猎物捕获中的作用上，但成功的猎物捕获需要快速的生理和生物力学机制。以捕食鱼类的 C. catus 为例，它利用高速液压机制将中空的、形似矛头的齿舌刺入猎物体内。我们通过将运动学研究与形态分析相结合，采用综合方法研究这一过程的生物力学。利用捕食软体动物的幼年梭子蜗牛 C. pennaceus 的不透明毒液和半透明喙，我们确定高速猎物捕获机制并非仅存在于捕食鱼类的蜗牛物种中。研究发现，有两种形态结构在这一过程中起着至关重要的作用。喙尖端附近的管腔变窄，由排列紧密的微丝组成的高上皮细胞组成，在齿舌推进之前阻碍其向前运动。在收缩处的近端，发现一个肌肉括约肌可以调节喙内毒液的流动和加压。在 C. pennaceus 中，在猎物捕获过程中，喙内毒液的快速出现和冲洗表明存在一种涉及输送离散量毒液的机制。这些元素之间的相互作用为快速作用的梭子蜗牛毒液肽提供了一种独特而有效的生物力学注射系统。
