Redirection of ambient light improves predator detection in a diurnal fish

Cases where animals use controlled illumination to improve vision are rare and thus far limited to chemiluminescence, which only functions in darkness. This constraint was recently relaxed by studies on Tripterygion delaisi, a small triplefin that redirects sunlight instead. By reflecting light sideways with its iris, it has been suggested to induce and detect eyeshine in nearby microprey. Here, we test whether \"diurnal active photolocation\" also improves T. delaisi's ability to detect a cryptobenthic sit-and-wait predator Scorpaena porcus, a scorpionfish with strong daytime retroreflective eyeshine. Three independent experiments revealed that triplefins in which light redirection was artificially suppressed approached scorpionfish significantly closer than two control treatments before moving away to a safer distance. Visual modelling confirmed that ocular light redirection by a triplefin is sufficiently strong to generate a luminance increase in scorpionfish eyeshine that can be perce...

动物利用受控照明（controlled illumination）提升视觉的案例极为罕见，迄今为止仅见于仅能在黑暗环境中发挥作用的化学发光（chemiluminescence）。这一局限近期被针对小型三鳍鳚（triplefin）Tripterygion delaisi的研究打破，该物种并非依赖化学发光，而是通过虹膜侧向反射光线来实现太阳光的重定向。此前研究推测，该物种可借此诱导并探测附近微型猎物的眼反射光（eyeshine）。本研究旨在检验这种"日间主动光定位（diurnal active photolocation）"是否同样能提升T. delaisi对隐蔽底栖伏击型捕食者褐菖鲉（Scorpaena porcus，一种具备强日间逆向反射眼反射光的鮋科鱼类）的探测能力。三组独立实验结果显示：人工抑制光线重定向功能的三鳍鳚，在撤离至安全距离前，会比两个对照组个体更近距离地接近褐菖鲉。视觉建模验证表明，三鳍鳚的眼部光线重定向效应足够强烈，足以使褐菖鲉的眼反射光产生可被感知的亮度提升……