Porter Marianne E, Roque Cassandra M, Long John H
Biology Department, Vassar College, Poughkeepsie, New York 12604, USA.
J Morphol. 2009 Aug;270(8):954-65. doi: 10.1002/jmor.10732.
Given the diversity of vertebral morphologies among fishes, it is tempting to propose causal links between axial morphology and body curvature. We propose that shape and size of the vertebrae, intervertebral joints, and the body will more accurately predict differences in body curvature during swimming rather than a single meristic such as total vertebral number alone. We examined the correlation between morphological features and maximum body curvature seen during routine turns in five species of shark: Triakis semifasciata, Heterodontus francisci, Chiloscyllium plagiosum, Chiloscyllium punctatum, and Hemiscyllium ocellatum. We quantified overall body curvature using three different metrics. From a separate group of size-matched individuals, we measured 16 morphological features from precaudal vertebrae and the body. As predicted, a larger pool of morphological features yielded a more robust prediction of maximal body curvature than vertebral number alone. Stepwise linear regression showed that up to 11 features were significant predictors of the three measures of body curvature, yielding highly significant multiple regressions with r(2) values of 0.523, 0.537, and 0.584. The second moment of area of the centrum was always the best predictor, followed by either centrum length or transverse height. Ranking as the fifth most important variable in three different models, the body's total length, fineness ratio, and width were the most important non-vertebral morphologies. Without considering the effects of muscle activity, these correlations suggest a dominant role for the vertebral column in providing the passive mechanical properties of the body that control, in part, body curvature during swimming.
鉴于鱼类椎体形态的多样性，很容易推测轴向形态与身体弯曲之间存在因果联系。我们认为，椎体、椎间关节和身体的形状及大小，比单一的可数特征（如仅椎体总数），能更准确地预测游泳时身体弯曲的差异。我们研究了5种鲨鱼（半带皱唇鲨、佛氏虎鲨、条纹斑竹鲨、点纹斑竹鲨和眼斑长尾鲨）在常规转弯时形态特征与最大身体弯曲度之间的相关性。我们使用三种不同指标量化了整体身体弯曲度。从另一组大小匹配的个体中，我们测量了尾前椎体和身体的16个形态特征。正如预测的那样，与仅考虑椎体数量相比，更多的形态特征能更有力地预测最大身体弯曲度。逐步线性回归表明，多达11个特征是身体弯曲度三种测量指标的显著预测因子，得到的多元回归高度显著，r²值分别为0.523、0.537和0.584。椎体中心的面积矩始终是最佳预测因子，其次是椎体长度或横向高度。在三种不同模型中位列第五重要变量的身体总长度、细长比和宽度，是最重要的非椎体形态特征。在不考虑肌肉活动影响的情况下，这些相关性表明脊柱在提供身体被动机械特性方面起主导作用，而这些特性在一定程度上控制着游泳时的身体弯曲度。
