Flammang B E, Lauder G V
Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
J Exp Biol. 2009 Jan;212(Pt 2):277-86. doi: 10.1242/jeb.021360.
Evolutionary patterns of intrinsic caudal musculature in ray-finned fishes show that fine control of the dorsal lobe of the tail evolved first, followed by the ability to control the ventral lobe. This progression of increasing differentiation of musculature suggests specialization of caudal muscle roles. Fine control of fin elements is probably responsible for the range of fin conformations observed during different maneuvering behaviors. Here, we examine the kinematics of the caudal fin and the motor activity of the intrinsic caudal musculature during kick-and-glide, braking and backing maneuvers, and compare these data with our previous work on the function of the caudal fin during steady swimming. Kick-and-glide maneuvers consisted of large-amplitude, rapid lateral excursion of the tail fin, followed by forward movement of the fish with the caudal fin rays adducted to reduce surface area and with the tail held in line with the body. Just before the kick, the flexors dorsalis and ventralis, hypochordal longitudinalis, infracarinalis and supracarinalis showed strong activity. During braking, the dorsal and ventral lobes of the tail moved in opposite directions, forming an ;S'-shape, accompanied by strong activity in the interradialis muscles. During backing up, the ventral lobe initiated a dorsally directed wave along the distal edge of the caudal fin. The relative timing of the intrinsic caudal muscles varied between maneuvers, and their activation was independent of the activity of the red muscle of the axial myomeres in the caudal region. There was no coupling of muscle activity duration and electromyographic burst intensity in the intrinsic caudal muscles during maneuvers, as was observed in previous work on steady swimming. Principal-component analysis produced four components that cumulatively explained 73.6% of the variance and segregated kick-and-glide, braking and backing maneuvers from each other and from steady swimming. The activity patterns of the intrinsic caudal muscles during maneuvering suggest motor control independent from myotomal musculature, and specialization of individual muscles for specific kinematic roles.
硬骨鱼内在尾肌的进化模式表明，尾部背叶的精细控制首先出现，随后才是控制腹叶的能力。这种肌肉组织分化程度不断增加的过程表明尾肌作用的专门化。鳍元素的精细控制可能是不同机动行为中观察到的鳍形态范围的原因。在这里，我们研究了踢水-滑行、制动和后退机动过程中尾鳍的运动学以及内在尾肌的运动活动，并将这些数据与我们之前关于稳定游泳时尾鳍功能的研究进行比较。踢水-滑行机动包括尾鳍大幅度、快速的横向摆动，随后鱼向前移动，尾鳍鳍条内收以减小表面积，且尾巴与身体保持在一条直线上。就在踢水之前，背侧屈肌和腹侧屈肌、下索纵肌、下棱肌和上棱肌表现出强烈的活动。在制动过程中，尾的背叶和腹叶向相反方向移动，形成一个“S”形，同时辐间肌有强烈活动。在后退时，腹叶沿着尾鳍的远端边缘引发一个背向的波。内在尾肌的相对时间在不同机动之间有所变化，并且它们的激活与尾区轴肌节红色肌肉的活动无关。在机动过程中，内在尾肌的肌肉活动持续时间和肌电图爆发强度之间没有耦合，这与之前关于稳定游泳的研究结果一致。主成分分析产生了四个成分，累计解释了73.6%的方差，并将踢水-滑行、制动和后退机动彼此区分开来，也与稳定游泳区分开来。机动过程中内在尾肌的活动模式表明其运动控制独立于肌节肌肉组织，并且个别肌肉针对特定运动学角色具有专门化。
