叶须虫目

见内文叶须虫目（学名：Phyllodocida）是多毛纲足刺亚纲之下一个目。这些物种主要在海洋生活，而有少量生活于咸淡水交界处。本目物种大多数是活跃的底栖生物，在沉积物的表面上移动或在当中挖洞，又或居住在基岩的裂缝和缝隙中。当中有部分物种会建造栖管，又有部分是浮游生物。据估计，约有3500种物种。叶须虫目是有体节物种，身长从数毫米到超过一米不等。每个体节均有一对桨似的疣足。口前叶一般有一对到两对眼睛，背部有一对触角，a ventral pair of sensory palps and a pair of organs on the neck. The peristomium is a ring, often hidden dorsally by the prostomium and the first segment. There is a muscular proboscis with one or more pairs of jaws. The next few segments tend to differ from those further back in having enlarged dorsal and ventral cirri (fine appendages) and reduced parapodial lobes and chaetae (bristles). Some species have appendages with specialised functions but most have many segments that are similar to each other but which vary in size and shape along the length of the body without abrupt changes in the chaetae and parapodia from one to the next.本目物种一般皆为捕食性动物或腐食性动物。本目的三个主要子群体为：鳞沙蚕亚目（Aphroditiformia）、吻沙蚕亚目（Glyceriformia）及沙蚕亚目（Nereidiformia）：There is agreement on the monophyly of a group including the Hesionidae, Nereididae and Chrysopetalidae families but opinions differ about Pilargidae, and molecular and morphological studies continue.叶须虫目原为足刺目之下的一个亚目。后来足刺目升格成为足刺亚纲，其下的叶须虫亚目亦升格成为叶须虫目。以下为本目所包含的四个亚目及再之下的各个科：鳞沙蚕亚目 Aphroditiformia：有文献把本亚目的分类单元再组成三个总科，但WoRMS质疑这种分类，只列出本亚目之下的科如下：吻沙蚕亚目 Glyceriformia沙蚕亚目 Nereidiformia叶须虫亚目 Phyllodociformia亚目地位未定