Fish F E, Holzman R
Department of Biology, West Chester University, West Chester, PA 19383, USA.
School of Zoology, Tel Aviv University and the Inter-University for Marine Sciences in Eliat, Eliat 88103, P.O. Box 469, Israel.
Integr Org Biol. 2019 Oct 10;1(1):obz025. doi: 10.1093/iob/obz025. eCollection 2019.
The typical orientation of a neutrally buoyant fish is with the venter down and the head pointed anteriorly with a horizontally oriented body. However, various advanced teleosts will reorient the body vertically for feeding, concealment, or prehension. The shrimpfish () maintains a vertical orientation with the head pointed downward. This posture is maintained by use of the beating fins as the position of the center of buoyancy nearly corresponds to the center of mass. The shrimpfish swims with dorsum of the body moving anteriorly. The cross-sections of the body have a fusiform design with a rounded leading edge at the dorsum and tapering trailing edge at the venter. The median fins (dorsal, caudal, anal) are positioned along the venter of the body and are beat or used as a passive rudder to effect movement of the body in concert with active movements of pectoral fins. Burst swimming and turning maneuvers by yawing were recorded at 500 frames/s. The maximum burst speed was 2.3 body lengths/s, but when measured with respect to the body orientation, the maximum speed was 14.1 body depths/s. The maximum turning rate by yawing about the longitudinal axis was 957.5 degrees/s. Such swimming performance is in line with fishes with a typical orientation. Modification of the design of the body and position of the fins allows the shrimpfish to effectively swim in the head-down orientation.
中性浮力鱼类的典型姿态是腹部向下，头部朝前，身体呈水平方向。然而，各种高等硬骨鱼会将身体垂直重新定向以进行捕食、隐藏或抓取。虾鱼（）保持头部向下的垂直姿态。这种姿态通过摆动鳍来维持，因为浮力中心的位置几乎与质心相对应。虾鱼游动时身体背部向前移动。身体的横截面呈梭形设计，背部有圆形前缘，腹部有逐渐变细的后缘。中位鳍（背鳍、尾鳍、臀鳍）沿着身体腹部排列，通过摆动或用作被动舵来与胸鳍的主动运动协同作用，使身体移动。以500帧/秒的速度记录了通过偏航进行的爆发式游泳和转弯动作。最大爆发速度为2.3体长/秒，但相对于身体姿态测量时，最大速度为14.1体深/秒。绕纵轴偏航的最大转弯速率为957.5°/秒。这种游泳性能与典型姿态的鱼类一致。身体设计和鳍的位置的改变使虾鱼能够有效地在头朝下的姿态下游泳。
