Institute of Zoology and Evolutionary Research, Friedrich Schiller University Jena, Erbertstraße 1, 07743 Jena, Germany
Zoological Institute, Kiel University, am Botanischen Garten 1-9, 24118 Kiel, Germany.
J Exp Biol. 2020 Nov 12;223(Pt 21):jeb232868. doi: 10.1242/jeb.232868.
Intraoral food processing mechanisms are known for all major vertebrate groups, but the form and function of systems used to crush, grind or puncture food items can differ substantially between and within groups. Most vertebrates display flexible mechanisms of intraoral food processing with respect to different environmental conditions or food types. It has recently been shown that newts use cyclical loop-motions of the tongue to rasp prey against the palatal dentition. However, it remains unknown whether newts can adjust their food processing behavior in response to different food types or environmental conditions. Newts are interesting models for studying the functional adaptation to different conditions because of their unique and flexible lifestyle: they seasonally change between aquatic and terrestrial habitats, adapt their prey-capture mode to the respective environment, and consume diverse food types with different mechanical properties. Using X-ray high-speed recordings, anatomical investigations, behavioral analyses and mechanical property measurements, we tested the effects of the medium in which feeding occurs (water/air) and the food type (maggot, earthworm, cricket) on the processing behavior in We discovered that food processing, by contrast to prey capture, differed only slightly between aquatic and terrestrial habitats. However, newts adjusted the number of processing cycles to different prey types: while maggots were processed extensively, earthworm pieces were barely processed at all. We conclude that, in addition to food mechanical properties, sensory feedback such as smell and taste appear to induce flexible processing responses, while the medium in which feeding occurs appears to have less of an effect.
口腔内的食物加工机制在所有主要的脊椎动物群体中都有发现，但用于粉碎、研磨或刺穿食物的系统的形式和功能在不同的群体之间和内部可能有很大的差异。大多数脊椎动物在不同的环境条件或食物类型下，对口腔内的食物加工具有灵活的机制。最近有人指出，蝾螈利用舌头的周期性环动来将猎物刮擦到腭齿上。然而，目前尚不清楚蝾螈是否能够根据不同的食物类型或环境条件来调整它们的食物加工行为。蝾螈是研究适应不同条件的功能的有趣模型，因为它们具有独特而灵活的生活方式：它们季节性地在水生和陆生栖息地之间变化，适应它们的捕食方式到各自的环境，并消耗具有不同机械性能的各种不同类型的食物。使用 X 射线高速录像、解剖学研究、行为分析和机械性能测量，我们测试了进食介质（水/空气）和食物类型（蛆、蚯蚓、蟋蟀）对处理行为的影响。我们发现，与捕食行为相比，食物处理在水生和陆生栖息地之间的差异很小。然而，蝾螈会根据不同的猎物类型调整处理的周期数：虽然蛆虫被广泛处理，但蚯蚓块几乎没有被处理。我们得出的结论是，除了食物的机械性能外，感官反馈，如气味和味道，似乎会引起灵活的处理反应，而进食的介质似乎影响较小。
