Consequences of the Calcite Skeletons of Planktonic Echinoderm Larvae for Orientation, Swimming, and Shape.
Consequences of the Calcite Skeletons of Planktonic Echinoderm Larvae for Orientation, Swimming, and Shape.
复制标题
浮游棘皮动物幼虫的方解石骨骼对定向、游泳和形状的影响。
DOI：
10.2307/1541746
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
R. R. Strathmann
中科院分区：
文献类型：
--
作者：
J. Pennington;R. R. Strathmann
通过实验去除plutei的骨骼并比较四个棘皮类的摄食幼虫，研究了棘皮类幼虫骨骼如何用于支持幼虫的手臂、被动定向和游泳。四种棘皮动物的幼虫在静水中都是前端向上的定向，但对活的和死的四肢棘皮动物的骨骼进行研究表明，它们的骨骼增强了前端向上的被动垂直定向。在对死去的有和没有骨骼的四肢棘龙的比较中，骨骼贡献了超过一半的多余密度和下沉速度。四种摄食棘皮类幼虫比较，骨骼体积较大、组织和体腔体积较小的幼虫密度最大。防止水藻下沉所需的计算功远远小于总有氧能量消耗的1%。因此方解石骨架对棘皮动物的被动垂直定向不是必需的，而是增强的，并且增加的密度和下沉速度对运动的能量消耗很小。幼虫骨骼的进化可能受到被动定向的好处和带着骨骼游泳的低成本的影响。无论骨骼的主要功能是什么，骨骼元素的位置和形式都受到后侧被动定位的功能要求的影响。增强被动垂直定向的特征包括后听骨和骨棒，骨棒后部增厚，幼体在幼虫后端附近形成。
How the echinoderm larval skeleton is used for support of larval arms, passive orientation, and swimming was examined by experimentally removing the skeletons of plutei and by comparing feeding larvae from four echinoderm classes. All four types of echinoderm larvae oriented with their anterior ends upward in still water, but removing the skeletons of both live and dead four-armed echinoplutei demonstrated that their skeletons enhanced passive vertical orientation with their anterior ends upward. In comparisons of dead four-armed echinoplutei with and without skeletons, the skeleton contributed more than half of the excess density and sinking speed. In comparisons of all four types of feeding echinoderm larvae, larvae with a greater volume of skeleton and a smaller volume of tissues and body cavity were densest. The calculated work necessary to prevent the plutei from sinking was much less than 1% of the total aerobic energy expenditure. Thus calcite skeletons are not essential for passive vertical orientation by echinoderm larvae but enhance it, and the increased density and sinking rates impose little energetic cost in locomotion. The evolution of larval skeletons may have been influenced by the benefits of passive orientation and by the low costs of swimming with a skeleton. Whatever the primary function of skeletons, the position and form of skeletal elements is influenced by the functional requirement for higher mass posteriorly for passive orientation. Features that enhance passive vertical orientation include posterior ossicles and skeletal rods, posterior thickening of skeletal rods, and formation of juvenile parts near the posterior ends of larvae.