鲨鱼
种系发生
系统进化关系的表示,通常显示为“树”(即。,branching diagram) where the most closely related organisms are connected by a node and more distantly related organisms have multiple steps back in the tree before they are connected. Nodes are often characterized by biogeographic events and evolutionary innovations. In fishes, jawless …(阅读更多…)
Heterocercal
heterocercal尾巴是一个由两个不对称尾鳍叶。通常,在许多鲨鱼等情况下,脊柱经过上部叶,使其成为更大的两叶。heterocercal尾巴是与homocercal尾巴等于叶。
软骨鱼纲
软骨鱼纲是软骨鱼类分类学类,包括鲨鱼和鳐鱼(板鳃类)和嵌合体。尽管也有例外,一般来说,软骨鱼纲暴露鳃,没有鱼鳔,体内受精,盾鳞状的齿。这些特征区分他们从更多的进化分支的鱼类中,硬骨鱼(硬骨鱼纲)。