Department of Biology, Dickinson College, Carlisle, PA, USA.
Biol Lett. 2012 Jun 23;8(3):473-6. doi: 10.1098/rsbl.2011.1105. Epub 2012 Jan 18.
Many species of snakes use constriction-the act of applying pressure via loops of their trunk-to subdue and kill their prey. Constriction is costly and snakes must therefore constrict their prey just long enough to ensure death. However, it remains unknown how snakes determine when their prey is dead. Here, we demonstrate that boas (Boa constrictor) have the remarkable ability to detect a heartbeat in their prey and, based on this signal, modify the pressure and duration of constriction accordingly. We monitored pressure generated by snakes as they struck and constricted warm cadaveric rats instrumented with a simulated heart. Snakes responded to the beating heart by constricting longer and with greater total pressure than when constricting rats with no heartbeat. When the heart was stopped midway through the constriction, snakes abandoned constriction shortly after the heartbeat ceased. Furthermore, snakes naive to live prey also responded to the simulated heart, suggesting that this behaviour is at least partly innate. These results are an example of how snakes integrate physiological cues from their prey to modulate a complex and ancient behavioural pattern.
许多蛇类使用缠绕身体的方式来收缩（通过施加压力来缠绕），以制服和杀死猎物。收缩是有代价的，因此蛇类必须恰当地收缩其猎物，以确保猎物死亡。然而，目前尚不清楚蛇类如何确定其猎物已经死亡。在这里，我们证明了蟒蛇（Boa constrictor）具有检测猎物心跳的非凡能力，并根据该信号相应地调整收缩的压力和持续时间。我们监测了蛇类在攻击和缠绕装有模拟心脏的温热尸体时产生的压力。当蛇类感觉到跳动的心脏时，它们会比收缩没有心跳的老鼠时更长时间、更大程度地施加总压力。当心脏在收缩过程中被中途停止时，蛇类会在心跳停止后不久放弃收缩。此外，对活体猎物一无所知的蛇类也对模拟心脏做出了反应，这表明这种行为至少部分是天生的。这些结果是蛇类如何整合来自猎物的生理线索来调节复杂而古老的行为模式的一个例子。
