发表机构
Johns Hopkins University（约翰斯·霍普金斯大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究探究弹涂鱼在不同湿度泥地的运动，发现其主要采用拐杖式步态，湿度过高时辅以尾部推力，尾部使用是其运动适应的主要创新点。
AI 中文摘要
在水陆界面，两栖鱼类会遇到由颗粒固液混合物构成的湿流动性基底，这类基底可保持固态或像流体一样流动。当这些基底变得更湿或更干时，其屈服强度（发生固液转变的临界值）和内聚力（黏性大小）都会发生变化，对运动构成挑战。尽管人们对四足动物在流动性基底（主要是干沙）上的运动已有大量了解，但对两栖鱼类如何应对不同湿度的湿流动性基底却知之甚少。本研究在发生固液转变的可控可变湿度黏土泥地上对弹涂鱼展开研究。随着泥地湿度增加，其强度降低了100倍，导致动物下沉更深，身体和鳍与泥地的接触面积更大；相比之下，泥地在中等湿度时最容易黏附。湿度更高的泥地中，下沉量、接触面积和黏性变化导致更多泥地黏附在动物身上并对其产生拉力；我们还测试了干泥，其黏液干燥后会黏附在动物鳍上。尽管面临这些挑战，弹涂鱼在除测试过的最湿泥地外，主要采用保守的拐杖式步态，仅出现适度的性能下降。当常规拐杖式运动效果降低时，动物会用尾部推力辅助：通过弯曲和伸直尾部向下、向后推，产生额外推力和升力，甚至用尾部推力跳跃。这些观察表明，弹涂鱼的拐杖式运动程序对其原生泥质基底适应良好但缺乏灵活性，尾部使用是其最主要的创新之处。
英文摘要
At the water-land interface, amphibious fishes encounter wet flowable substrates made of granular solid-water mixtures, which can stay solid or flow like a fluid. As these substrates become wetter or drier, their yield strength (at which solid-fluid transition occurs) and cohesion (how sticky they are) both change, challenging locomotion. Despite substantial understanding of tetrapod locomotion on flowable substrates (mostly dry sand), we know little about how amphibious fishes cope with wet flowable substrates of various wetness. Here, we studied mudskippers on clay mud of controlled, variable wetness over the range where solid-fluid transition occurs. As mud became wetter, its strength decreased by 100-fold, leading the animal to sink deeper, with larger areas of body and fins contacting mud. By contrast, mud stuck most easily at intermediate wetness. The increased sinkage and contact and stickiness change caused more mud to stick to and pull against the animal on wetter mud. We also tested dry mud, which stuck to animal fins as its mucus dried. Despite these challenges, the mudskipper predominately used a conserved crutching gait on all except the wettest mud tested, with a modest performance reduction. When normal crutching became less effective, the animal assisted it with tail thrusting, by bending and straightening it to push downward and backward to generate additional thrust and lift, or even thrusting the tail to jump. These observations suggest that mudskipper's crutching motor program is well adapted to its native muddy substrates but inflexible, with most novelty in tail use.
CommentsJournal of Experimental Biology, in review
