Odor plumes and how blue crabs use them in finding prey.
Odor plumes and how blue crabs use them in finding prey.
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发表时间：
1994-12
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通讯作者：
M. Weissburg;R. K. Zimmer-Faust
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作者：
M. Weissburg;R. K. Zimmer-Faust
利用化学线索对动物进行定向通常发生在流动中，其中气味的刺激特性受到流体运动特性的影响。对动物对气味羽流做出反应的运动模式的运动学分析已经被用来提供对嗅觉调节定向的行为和生理方面的洞察，特别是在陆地昆虫中。我们用这种方法分析了在受控的水动力环境中，蓝蟹对活贝虹吸释放的诱饵代谢物的羽流做出的捕食性搜索。蟹类以顺畅湍动的水流向上游直接向文蛤进发，并表现出较高的运动速度和很少的静止周期。蟹类具有更多的间接运动轨迹，在粗糙-湍流中表现出较慢的运动速度和较多的停顿。这种觅食性能的下降是最明显的，当水流从光滑的湍流状态转变为粗糙的湍流状态时，水力特性的变化与边界层粘性亚层区域的收缩有关。由于这一区域的流动是准层流，粘性亚层可能是化学刺激传递的一种特别有效的载体，因此当它被减少或移除时，定向会严重受损。我们的结果还表明，流变和化学信息都是成功定向所必需的。对化学物质的感知起到了偏向运动逆流的作用，而气味刺激分布的反馈似乎直接控制了随后的停止和转向猎物的途中。尽管昆虫和蓝蟹对气味羽流的定向机制基本相似，但蓝蟹似乎比昆虫系统更严重地依赖化学刺激分布的空间和/或时间方面。
Orientation of animals using chemical cues often takes place in flows, where the stimulus properties of odorants are affected by the characteristics of fluid motion. Kinematic analysis of movement patterns by animals responding to odor plumes has been used to provide insight into the behavioral and physiological aspects of olfactory-mediated orientation, particularly in terrestrial insects. We have used this approach in analyzing predatory searching by blue crabs in response to plumes of attractant metabolites released from the siphons of live clams in controlled hydrodynamic environments. Crabs proceed directly upstream towards clams in smooth-turbulent flows and show high locomotory velocities and few periods of motionlessness. Crabs assume more indirect trajectories and display slower locomotion and more stopping in rough-turbulent flows. This degradation of foraging performance is most pronounced as flow shifts from a smooth- to a rough-turbulent regime, where the change in hydraulic properties is associated with contraction of the viscous sublayer region of the boundary layer. Because flow in this region is quasilaminar, the viscous sublayer may be a particularly effective vehicle for chemical stimulus transmission, such that orientation is severely compromised when it is reduced or removed. Our results also suggest that rheotactic and chemical information are both necessary for successful orientation. Perception of chemical cues acts to bias locomotion upcurrent, and feedback from odorant stimulus distributions appears directly to regulate subsequent stopping and turning en route to prey. Although the mechanisms of orientation to odorant plumes displayed by insects and blue crabs are largely similar, blue crabs appear to rely more heavily on spatial and/or temporal aspects of chemical stimulus distributions than has been suggested for insect systems.