Stalked crinoids have long been considered sessile. In the 1980s, however, observations both in the field and of laboratory experiments proved that some of them (isocrinids) can actively relocate by crawling with their arms on the substrate, and dragging the stalk behind them. Although it has been argued that this activity may leave traces on the sediment surface, no photographs or images of the traces produced by crawling crinoids have been available. Herein, we present results of neoichnological experiments using the shallowest species of living stalked crinoid, Metacrinus rotundus, dredged from Suruga Bay (near the town of Numazu, Shizuoka Prefecture, ~ 140 m depth). Our results demonstrate that isocrinids produce characteristic locomotion traces, which have some preservation potential. They are composed of rather deep and wide, sometimes weakly sinuous, central drag marks left by the stalk and cirri, and short, shallow scratch marks made by the arms. Based on the functional morphology and taphonomy, it has been argued that the ability to autotomize the stalk and relocate had already evolved in the oldest stem-group isocrinids (holocrinids), likely in response to increased benthic predation pressure during the so-called Mesozoic marine revolution. Our data show that this hypothesis may be corroborated in the future by ichnological findings, which may provide more direct proof of active locomotion in Triassic holocrinids.

中文翻译：

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爬行的茎状海百合的实验新技术

长期以来，茎秆类固醇一直被认为是无柄的。但是，在1980年代，在现场和实验室实验中的观察都证明，其中的某些（异c类）可以通过将其手臂爬行在基底上并将茎杆拖到其后方来主动迁移。尽管有人认为这种活动可能会在沉积物表面上留下痕迹，但尚无爬行的类海百合产生的痕迹的照片或图像。在这里，我们介绍了使用从浅野湾（静冈县沼津市附近，深约140 m的深度）挖出的最浅的活茎类海百合，圆形cri鱼（Metacrinus rotundus）进行的新技术实验的结果。我们的结果表明，异旋风虫可产生特征性的运动轨迹，具有一定的保存潜力。它们由相当深而广泛的组成，有时由茎和卷毛留下轻微弯曲的中央拖曳痕迹，而手臂则留下短而浅的划痕。基于功能形态学和拓扑学，有人认为，在最古老的茎群异oc鱼（holocrinids）中已经进化出了使茎自动解剖和迁移的能力，这可能是由于所谓的中生代海洋中底栖捕食压力的增加所致。革命。我们的数据表明，这一假说可能会在未来的鱼卵学发现中得到证实，这可能会为三叠纪全人类的主动运动提供更直接的证据。有人认为，在最古老的茎群异旋体（holocrinids）中，茎秆自动重定位的能力已经得到了发展，这可能是由于所谓的中生代海洋革命期间底栖捕食压力的增加所致。我们的数据表明，这一假说可能会在未来的鱼卵学发现中得到证实，这可能会为三叠纪全人类的主动运动提供更直接的证据。有人认为，在最古老的茎群异旋体（holocrinids）中，茎秆自动重定位的能力已经得到了发展，这可能是由于所谓的中生代海洋革命期间底栖捕食压力的增加所致。我们的数据表明，这一假说可能会在未来的鱼卵学发现中得到证实，这可能会为三叠纪全人类的主动运动提供更直接的证据。