Comatulid and isocrinid crinoids have flexible, motile attachment structures called cirri that articulate synarthrially. In other crinoids, structures that are superficially similar, yet non-motile, articulating symplectially or synostially and in some taxa branched, are referred to as radices or radicles. To refer to a ‘root’ structure as a cirrus just because it is unbranched is erroneous. Obviously, this distinction has both functional and phylogenetic implications. Cirri are unbranched, but so are many radices.

中文翻译：

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卷云与辐射：混淆海百合术语的简要研究

Comatulid 和 isocrinid 海百合具有灵活的、能动的附着结构，称为 cirri，可通过合关节进行发音。在其他海百合中，表面相似但不运动的结构，在某些分类群中分枝，被称为基根或胚根。仅仅因为“根”结构没有分支就将其称为卷云是错误的。显然，这种区别具有功能和系统发育意义。Cirri 是无分支的，但许多 radices 也是如此。