Shell form and the ecological range of living and extinct Arcoida
Shell form and the ecological range of living and extinct Arcoida
复制标题
现存和灭绝的Arcoida的贝壳形状和生态范围
作者：
R. D. Thomas
弧形双壳类无论在形态上还是在适应范围上都处于翼手目和金翅目之间的中间位置。弧形适应的范围和限制与其壳的生长模式有关。弧形铰链和韧带都是通过简单结构的连续重复而生长的，这与其他群体中更专业、更复杂的结构的发展形成鲜明对比。这些简单的生长模式对可能的壳形状范围产生了显着的机械限制。大多数弧状体生活在中等不稳定的环境中，它们很容易被挖掘或从其基底上分离。许多人采用恢复策略，适应重新获得生活状态。然而，与其他双壳类群体趋同的各种特殊形式已经变得适应，以避免从一开始就被驱逐。因此，内在的生长模式和基质关系是Arcoida进化的主要因素。
Arcoid bivalves occupy an intermediate position, in terms both of morphology and of adaptive range between the Pterioida and the Veneroida. The range and limits of arcoid adaptations are related to the growth patterns of their shells. Both the arcoid hinge and ligament grow by the serial repetition of simple structures, in contrast with the development of more specialized, complex structures in other groups. These simple growth patterns place significant mechanical constraints on the range of possible shell forms. Most arcoids live in moderately unstable environments, where they are liable to be excavated or detached from their substrates. Many employ recovery strategies, being adapted to regain their life positions. However, a variety of specialized forms, convergent on other groups of bivalves, have become adapted to avoid being dislodged in the first place. Thus, intrinsic growth patterns and substrate relationships have been the major factors in the evolution of the Arcoida.