Department of Ecology and Evolution, University of California, Irvine, CA 92697-2525, USA.
J Exp Biol. 2010 Nov 15;213(Pt 22):3769-77. doi: 10.1242/jeb.046946.
The ability of a predator fish to capture a prey fish depends on the hydrodynamics of the prey and its behavioral response to the predator's strike. Despite the importance of this predator-prey interaction to the ecology and evolution of a diversity of fish, it is unclear what factors dictate a fish's ability to evade capture. The present study evaluated how the specific gravity of a prey fish's body affects the kinematics of prey capture and the signals detected by the lateral line system of the prey during the strike of a suction-feeding predator. The specific gravity of zebrafish (Danio rerio) larvae was measured with high precision from recordings of terminal velocity in solutions of varying density. This novel method found that specific gravity decreased by ∼5% (from 1.063, N=8, to 1.011, N=35) when the swim bladder inflates. To examine the functional consequences of this change, we developed a mathematical model of the hydrodynamics of prey in the flow field created by a suction-feeding predator. This model found that the observed decrease in specific gravity due to swim bladder inflation causes an 80% reduction of the flow velocity around the prey's body. Therefore, swim bladder inflation causes a substantial reduction in the flow signal that may be sensed by the lateral line system to evade capture. These findings demonstrate that the ability of a prey fish to sense a predator depends crucially on the specific gravity of the prey.
掠食性鱼类捕捉猎物的能力取决于猎物的流体动力学特性及其对掠食者攻击的行为反应。尽管这种捕食者-猎物相互作用对各种鱼类的生态和进化至关重要，但目前尚不清楚是什么因素决定了鱼类逃避被捕食的能力。本研究评估了猎物鱼体比重如何影响猎物在吸吮式捕食者攻击时的运动学和侧线系统检测到的信号。通过在不同密度溶液中记录终端速度，高精度地测量了斑马鱼（Danio rerio）幼虫的比重。这项新方法发现，当鳔充气时，比重从 1.063（N=8）下降到 1.011（N=35），下降了约 5%。为了研究这种变化的功能后果，我们开发了一个侧线系统在吸吮式捕食者产生的流场中猎物水动力的数学模型。该模型发现，由于鳔充气导致的观察到的比重下降导致猎物身体周围的流速减少了 80%。因此，鳔充气会导致侧线系统可能感知到的流动信号大幅减少，从而逃避被捕食。这些发现表明，猎物鱼感知捕食者的能力取决于猎物的比重。
