Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620, USA.
Bermuda Institute of Ocean Sciences, St George's GE01, Bermuda.
J Exp Biol. 2018 Dec 7;221(Pt 23):jeb192062. doi: 10.1242/jeb.192062.
Atlantiid heteropods are zooplanktonic marine snails which have a calcium carbonate shell and single swimming fin. They actively swim to hunt prey and vertically migrate. Previous accounts of atlantiid heteropod swimming described these animals sculling with the swimming fin while the shell passively hung beneath the body. Here, we show, via high-speed stereophotogrammetric measurements of body, fin and shell kinematics, that the atlantiid heteropod actively flaps both the swimming fin and shell in a highly coordinated wing-like manner in order to swim in the intermediate Reynolds number regime (=10-100). The fin and shell kinematics indicate that atlantiid heteropods use unsteady hydrodynamic mechanisms such as clap-and-fling and delayed stall. Unique features of atlantiid heteropod swimming include the coordinated pairing of dissimilar appendages, use of the clap and fling mechanism twice during each stroke cycle, and the fin's extremely large stroke amplitude, which exceeds 180 deg.
亚特兰蒂异足类是浮游性海洋蜗牛，具有碳酸钙壳和单个游泳鳍。它们积极游动以捕食猎物并垂直迁移。先前对亚特兰蒂异足类游泳的描述表明，这些动物在游泳鳍上划桨，而壳则被动地挂在身体下方。在这里，我们通过对身体、鳍和壳运动学的高速立体摄影测量显示，为了在中间雷诺数范围内（=10-100）游动，亚特兰蒂异足类积极地以高度协调的翼状方式扇动游泳鳍和壳。鳍和壳的运动学表明，亚特兰蒂异足类使用非定常水动力机制，如拍打和甩动以及延迟失速。亚特兰蒂异足类游泳的独特特征包括不同附肢的协调配对、在每个划水周期中使用拍打和甩动机制两次，以及鳍的极长的冲程幅度，超过 180 度。
