Department of Biology, Hampden-Sydney College, Hampden-Sydney, Virginia, USA.
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA.
J Anat. 2023 Sep;243(3):343-373. doi: 10.1111/joa.13876. Epub 2023 Apr 12.
Cetaceans are atypical mammals whose tongues often depart from the typical (basal) mammalian condition in structure, mobility, and function. Their tongues are dynamic, innovative multipurpose tools that include the world's largest muscular structures. These changes reflect the evolutionary history of cetaceans' secondary adaptation to a fully aquatic environment. Cetacean tongues play no role in mastication and apparently a greatly reduced role in nursing (mainly channeling milk ingestion), two hallmarks of Mammalia. Cetacean tongues are not involved in drinking, breathing, vocalizing, and other non-feeding activities; they evidently play no or little role in taste reception. Although cetaceans do not masticate or otherwise process food, their tongues retain key roles in food ingestion, transport, securing/positioning, and swallowing, though by different means than most mammals. This is due to cetaceans' aquatic habitat, which in turn altered their anatomy (e.g., the intranarial larynx and consequent soft palate alteration). Odontocetes ingest prey via raptorial biting or tongue-generated suction. Odontocete tongues expel water and possibly uncover benthic prey via hydraulic jetting. Mysticete tongues play crucial roles driving ram, suction, or lunge ingestion for filter feeding. The uniquely flaccid rorqual tongue, not a constant volume hydrostat (as in all other mammalian tongues), invaginates into a balloon-like pouch to temporarily hold engulfed water. Mysticete tongues also create hydrodynamic flow regimes and hydraulic forces for baleen filtration, and possibly for cleaning baleen. Cetacean tongues lost or modified much of the mobility and function of generic mammal tongues, but took on noteworthy morphological changes by evolving to accomplish new tasks.
鲸类动物是一种非典型的哺乳动物，其舌头在结构、移动性和功能上常常与典型的（基础）哺乳动物状况不同。它们的舌头是动态的、创新的多用途工具，其中包括世界上最大的肌肉结构。这些变化反映了鲸类动物对完全水生环境的二次适应的进化历史。鲸类动物的舌头在咀嚼和哺乳（主要是引导乳汁摄入）中不起作用，这是哺乳动物的两个显著特征。鲸类动物的舌头不参与饮水、呼吸、发声和其他非摄食活动；它们显然在味觉接收方面没有发挥作用或作用很小。尽管鲸类动物不咀嚼或处理食物，但它们的舌头在食物摄入、运输、固定/定位和吞咽方面仍然发挥着关键作用，尽管它们的方式与大多数哺乳动物不同。这是由于鲸类动物的水生栖息地，这反过来又改变了它们的解剖结构（例如，鼻腔内的喉和随之而来的软腭改变）。齿鲸通过捕食性的咬或舌产生的吸力摄取猎物。齿鲸的舌头通过水力喷射排出水并可能揭开海底猎物。须鲸的舌头在过滤进食时，对于推动、抽吸或冲刺摄食起着至关重要的作用。独特的柔软须鲸舌头不是一个恒定体积的流体静力学（与所有其他哺乳动物的舌头一样），而是通过内陷形成一个气球状的袋状结构，暂时容纳被吞噬的水。须鲸的舌头还为须鲸过滤产生了流场和水力，也可能用于清洁须鲸的鲸须。鲸类动物失去或改变了普通哺乳动物舌头的大部分活动性和功能，但通过进化来完成新的任务，获得了显著的形态变化。
