Werth Alexander J
Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA.
J Exp Biol. 2004 Sep;207(Pt 20):3569-80. doi: 10.1242/jeb.01202.
Anatomical and behavioral analyses suggest that the filtration mechanism of bowhead and right whales (Balaenidae) is driven by hydrodynamic as well as ram hydraulic pressures. Complementary models were devised to investigate biomechanical aspects of water flow in the buccal cavity of the bowhead whale Balaena mysticetus during continuous filter feeding. A mathematical model was created to test and quantify water flow predictions with steady state hydromechanical equations; a physical model of the bowhead mouth (approximately 1/15 scale) was constructed to visualize flow processes. Both models rely on morphometric data obtained from whales harvested by Inupiat Eskimos for subsistence purposes along with information on foraging ecology (locomotor velocity, gape, etc.). Results indicate that unique features of balaenid oral construction and function (e.g. subrostral gap, orolabial sulcus, curvature of baleen, extensive mandibular rotation and lingual mobility) not only permit steady, unidirectional flow of water through the mouth, but also establish Bernoulli and Venturi effects during feeding. These hydrodynamic conditions allow balaenids to improve filtering efficiency and avoid creation of an anterior compressive wave (by increasing flow velocity and thereby reducing pressure) so that they may capture elusive prey even at slow swimming speeds.
解剖学和行为学分析表明,弓头鲸和露脊鲸(须鲸科)的滤食机制是由流体动力以及冲压液压驱动的。设计了互补模型来研究弓头鲸(Balaena mysticetus)在持续滤食过程中口腔内水流的生物力学方面。创建了一个数学模型,用稳态流体力学方程来测试和量化水流预测;构建了一个弓头鲸口部的物理模型(约为1/15比例)以可视化水流过程。两个模型都依赖于因努伊特爱斯基摩人为维持生计而捕获的鲸鱼的形态测量数据以及觅食生态学信息(运动速度、口裂等)。结果表明,须鲸科动物口腔结构和功能的独特特征(例如吻下间隙、口唇沟、鲸须曲率、下颌广泛旋转和舌的活动度)不仅允许水稳定、单向地流过口腔,而且在进食过程中还会产生伯努利效应和文丘里效应。这些流体动力条件使须鲸科动物能够提高过滤效率并避免产生前部压缩波(通过提高流速从而降低压力),这样它们即使在缓慢游动速度下也能捕获难以捉摸的猎物。