变色龙舌头上分泌的唾液黏性比人的唾液要高400倍左右，这或许可以解释这些捕食者是如何捕获重量为其体重1/3的猎物的。

6月20日，发表在《Nature Physics》上的一项多学科研究，组合了实验数据与力学模型，显示这种黏性附着力足以解释变色龙在捕猎成功时其舌头和猎物之间形成的连接。

变色龙是一种机会捕食者，在感觉到捕食范围内出现猎物之前都会保持不动并隐蔽。它们弹出舌头可以触到距离其身体长度两倍远的猎物。然而，变色龙的舌头粘住猎物的机制，人们至今还不清楚。目前，研究人员已经提出若干模型，包括真空吸附，涉及舌头与猎物粗糙表面的交联机制。

比利时蒙斯大学Pascal Damman团队显示，变色龙黏液的黏合性足以在没有其他因素的情况下起效。研究团队确定了变色龙舌垫处分泌的黏液的黏性。根据黏性的测量数据，研究者建立了一个模型描述了变色龙舌头是如何利用这种高黏性来捕获猎物的，并且这种机制的解释和对于不同品种的变色龙的观察相符度很高。

研究人员总结道，由于变色龙唾液的高黏性以及猎物和舌头之间较大的接触面积，黏性附着力不是捕捉猎物大小的限制因素。（来源：中国科学报 唐凤）

Dynamics of prey prehension by chameleons through viscous adhesion

Abstract  Among predators using an adhesive tongue to feed, chameleons are able to capture large prey by projecting the tongue at high acceleration. Once in contact with a prey, the tongue retracts with a comparable acceleration to bring it to the mouth. A strong adhesion between the tongue tip and the prey is therefore required during the retraction phase to ensure a successful capture. To investigate the mechanism responsible for this strong bond, the viscosity of the mucus produced at the chameleon’s tongue pad is measured, using the viscous drag exerted on rolling beads by a thin layer of mucus. Here we show that the viscosity of this secretion is about 400 times larger than that of human saliva. We incorporate this viscosity into a dynamical model for viscous adhesion, which describes the motion of the compliant tongue and the prey during the retraction phase. The variation of the maximum prey size with respect to the chameleon body length is derived, and compared with in vivo observations for various chameleon species. Our study shows that the size of the captured prey is not limited by viscous adhesion, owing to the high mucus viscosity and large contact area between the prey and the tongue.

原文链接：http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3795.html