Shearing overbite and asymmetrical jaw motions facilitate food breakdown in a freshwater stingray, Potamotrygon motoro
Shearing overbite and asymmetrical jaw motions facilitate food breakdown in a freshwater stingray, Potamotrygon motoro
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DOI：
10.1242/jeb.197681
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发表时间：
2019-07-01
影响因子：
2.8
通讯作者：
Brainerd, Elizabeth L.
中科院分区：
文献类型：
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作者：
Laurence-Chasen, J. D.;Ramsay, Jason B.;Brainerd, Elizabeth L.
许多种类的鱼类处理猎物的周期性颌运动，这与哺乳动物咀嚼的方式非常相似，尽管牙齿和颌的形态完全不同。这些不同类群的加工行为之间的相似程度对我们理解脊椎动物摄食系统的趋同性有影响。在这里，我们使用XROMM（X射线重建的移动形态），调查猎物加工行为的Potamotrygon motoro，ocellate河黄貂鱼，最近被发现采用不对称的，剪切下颌运动，打破它的猎物。我们发现，P. motoro调节其进食运动学产生两种不同类型的咀嚼周期：压缩周期和覆咬周期。后者的特征是上颌相对于下颌过度旋转，超过预期的咬合极限，以及与压缩咀嚼相比更高水平的双侧不对称。我们没有发现哺乳动物咀嚼的典型的中外侧剪切运动的证据，但覆咬周期似乎在propalinal方式的上下齿板之间剪切猎物。此外，比较舌骨下颌和颌骨运动表明，角软骨解耦下颌位移从舌骨下颌位移在喙尾和内外侧方向。哺乳动物的咀嚼和P. motoro的动态加工行为之间的多个相似性支持使用亚科Potamotrigoninae作为研究咀嚼样加工进化趋同的模型。
Many species of fish process their prey with cyclic jaw motions that grossly resemble those seen in mammalian mastication, despite starkly different tooth and jaw morphologies. The degree of similarity between the processing behaviors of these disparate taxa has implications for our understanding of convergence in vertebrate feeding systems. Here, we used XROMM (X-ray reconstruction of moving morphology) to investigate prey processing behavior of Potamotrygon motoro, the ocellate river stingray, which has recently been found to employ asymmetrical, shearing jaw motions to break down its prey. We found that P. motoro modulates its feeding kinematics to produce two distinct types of chew cycles: compressive cycles and overbite cycles. The latter are characterized by over-rotation of the upper jaw relative to the lower jaw, past the expected occlusal limit, and higher levels of bilateral asymmetry as compared with compressive chews. We did not find evidence of the mediolateral shearing motions typical of mammalian mastication, but overbite cycles appear to shear the prey item between the upper and lower toothplates in a propalinal fashion. Additionally, comparison of hyomandibular and jaw motions demonstrates that the angular cartilages decouple jaw displacement from hyomandibular displacement in rostrocaudal and mediolateral directions. The multiple similarities between mammalian mastication and the dynamic processing behavior of P. motoro support the use of subfamily Potamotrygoninae as a model for studying evolutionary convergence of mastication-like processing.