Van Wassenbergh Sam, Aerts Peter, Herrel Anthony
Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium.
J Exp Biol. 2005 Jun;208(Pt 11):2103-14. doi: 10.1242/jeb.01603.
Scaling effects on the kinematics of suction feeding in fish remain poorly understood, at least partly because of the inconsistency of the results of the existing experimental studies. Suction feeding is mechanically distinct from most other type of movements in that negative pressure inside the buccal cavity is thought to be the most important speed-limiting factor during suction. However, how buccal pressure changes with size and how this influences the speed of buccal expansion is unknown. In this paper, the effects of changes in body size on kinematics of suction feeding are studied in the catfish Clarias gariepinus. Video recordings of prey-capturing C. gariepinus ranging in total length from 111 to 923 mm were made, from which maximal displacements, velocities and accelerations of several elements of the cranial system were determined. By modelling the observed expanding head of C. gariepinus as a series of expanding hollow elliptical cylinders, buccal pressure and power requirement for the expansive phase of prey capture were calculated for an ontogenetic sequence of catfish. We found that angular velocities decrease approximately proportional with increasing cranial size, while linear velocities remain more or less constant. Although a decreasing (angular) speed of buccal expansion with increasing size could be predicted (based on calculations of power requirement and the expected mass-proportional scaling of available muscular power in C. gariepinus), the observed drop in (angular) speed during growth exceeds these predictions. The calculated muscle-mass-specific power output decreases significantly with size, suggesting a relatively lower suction effort in the larger catfish compared with the smaller catfish.
体型大小对鱼类吸食运动学的影响仍未得到充分理解，至少部分原因是现有实验研究结果不一致。吸食在力学上与大多数其他类型的运动不同，因为口腔内的负压被认为是吸食过程中最重要的速度限制因素。然而，口腔压力如何随体型大小变化以及这如何影响口腔扩张速度尚不清楚。在本文中，研究了体型变化对胡子鲶（Clarias gariepinus）吸食运动学的影响。对全长从111毫米到923毫米的捕食猎物的胡子鲶进行了视频记录，从中确定了颅骨系统几个部位的最大位移、速度和加速度。通过将观察到的胡子鲶头部扩张建模为一系列扩张的空心椭圆圆柱体，计算了捕食猎物扩张阶段的口腔压力和功率需求，以研究胡子鲶的个体发育序列。我们发现，角速度随着颅骨尺寸的增加大致成比例下降，而线速度或多或少保持恒定。尽管随着体型增大，口腔扩张速度下降（角速度）是可以预测的（基于功率需求计算以及胡子鲶中可用肌肉力量的预期质量比例缩放），但观察到的生长过程中（角速度）速度下降超过了这些预测。计算得出的肌肉质量比功率输出随着体型显著降低，这表明与较小的胡子鲶相比，较大的胡子鲶的吸食力度相对较低。
