Recent findings have greatly improved our understanding of mysticete oral filtration, and have upended the traditional view of baleen filtration as a simple process. Flow tank experiments, telemetric tag deployment on whales, and other lab and field methods continue to yield new data and ideas. These suggest that several mechanisms arose from ecological, morphological, and biomechanical adaptations facilitating the evolution of extreme body size in Mysticeti. Multiple lines of evidence strongly support a characterization of baleen filtration as a conceptually dynamic process, varying according to diverse intraoral locations and times of the filtration process, and to other prevailing conditions. We review and highlight these lines of evidence as follows. First, baleen appears to work as a complex metafilter comprising multiple components with differing properties. These include major and minor plates and eroded fringes (AKA bristles or hairs), as well as whole baleen racks. Second, it is clear that different whale species rely on varied ecological filtration modes ranging from slow skimming to high-speed lunging, with other possibilities in between. Third, baleen filtration appears to be a highly dynamic and flow-dependent process, with baleen porosity not only varying across sites within a single rack, but also by flow direction, speed, and volume. Fourth, findings indicate that baleen (particularly of balaenid whales and possibly other species) generally functions not as a simple throughput sieve, but instead likely uses cross-flow or other tangential filtration, as in many biological systems. Fifth, evidence reveals that the time course of baleen filtration, including rate of filter filling and clearing, appears to be more complex than formerly envisioned. Flow direction, and possibly plate and fringe orientation, appears to change during different stages of ram filtration and water expulsion. Sixth, baleen’s flexibility and related biomechanical properties varies by location within the whole filter (=rack), leading to varying filtration conditions and outcomes. Seventh, the means of clearing/cleaning the baleen filter, whether by hydraulic, hydrodynamic, or mechanical methods, appears to vary by species and feeding type, notably intermittent lunging versus continuous skimming. Together, these and other findings of the past two decades have greatly elucidated processes of baleen filtration, and heightened the need for further research. Many aspects of baleen filtration may pertain to other biological filters; designers can apply several aspects to artificial filtration, both to better understand natural systems and to design and manufacture more effective synthetic filters. Understanding common versus unique features of varied filtration phenomena, both biological and artificial, will continue to aid scientific and technical understanding, enable fruitful interdisciplinary partnerships, and yield new filter designs.

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须鲸的动态过滤：最新发现和新兴趋势

最近的研究结果极大地提高了我们对须鲸口腔过滤的理解，并颠覆了鲸须过滤作为一个简单过程的传统观点。流槽实验、鲸鱼遥测标签部署以及其他实验室和现场方法不断产生新的数据和想法。这些表明，生态、形态和生物力学适应中产生了多种机制，促进了Mysticeti极端体型的进化。多种证据有力地支持鲸须过滤作为概念上的动态过程的特征，根据不同的口腔内位置和过滤过程的时间以及其他普遍条件而变化。我们回顾并强调这些证据如下。首先，鲸须似乎是一个复杂的元过滤器，由具有不同特性的多个组件组成。其中包括主要和次要板块和侵蚀的边缘（又名刚毛或毛发），以及整个鲸须架。其次，很明显，不同的鲸鱼物种依赖于不同的生态过滤模式，从缓慢的掠过到高速的冲刺，以及介于两者之间的其他可能性。第三，鲸须过滤似乎是一个高度动态且依赖于流量的过程，鲸须孔隙率不仅在单个机架内的不同位置上变化，而且还随流向、速度和体积变化。第四，研究结果表明，须鲸（尤其是须鲸和可能的其他物种）通常不是作为简单的吞吐量筛，而是可能使用错流或其他切向过滤，就像在许多生物系统中一样。第五，有证据表明鲸须过滤的时间过程，包括过滤器填充和清除的速度，似乎比以前想象的更复杂。在冲压过滤和排水的不同阶段，流动方向以及可能的板和边缘方向似乎会发生变化。第六，鲸须的灵活性和相关的生物力学特性因整个过滤器（=机架）内的位置而异，导致过滤条件和结果不同。第七，清除/清洁鲸须过滤器的方法，无论是通过液压、流体动力还是机械方法，似乎因物种和进食类型而异，特别是间歇性冲刺与连续撇油。总之，过去二十年的这些发现和其他发现极大地阐明了鲸须过滤过程，并增加了进一步研究的必要性。鲸须过滤的许多方面可能与其他生物过滤器有关；设计师可以将多个方面应用于人工过滤，既可以更好地了解自然系统，也可以设计和制造更有效的合成过滤器。了解各种生物和人工过滤现象的共同特征和独特特征将继续有助于科学和技术理解，实现富有成效的跨学科合作，并产生新的过滤器设计。