Acoela, or the acoels, is an order of small and simple invertebrates in the subphylum Acoelomorpha of phylum Xenacoelomorpha, a deep branching bilaterian group of animals, which resemble flatworms. Historically they were treated as an order of turbellarian flatworms .

（Acoela） 生活在海水中，小型涡虫，体长1mm-12mm，通常约2mm，体长圆形，口位于近中央的腹中线上，有的具一简单的咽，无消化管，有一团来源于内胚层的 营养细胞 进行吞噬和消化。无原肾管，神经系统很不发达（包括脑及多条神经索并连成网状），有的为 ...

Acoels are bilaterally symmetric, microscopic worms, typically in the millimeter-size range, that are found predominantly in benthic marine habitats. They can easily be recognized by the presence of a characteristic statocyst at the anterior end (see sensory organs; Figs. 1, 2a, b, d).

无腔动物亚门（学名：Acoelomorpha）是异无腔动物门下的一个亚门。 它们拥有浮浪幼虫样动物的特征，以往被认为是属于后口动物，但有学者将它们成立为一个独立于后口动物的门。 经过miRNA分析，若按照亲缘分支分类法应分类于异无腔动物门之下。 无腔动物差不多完全是水生的，栖息在沉积物中，游泳像浮游生物或在藻类上爬行。 它们有平衡囊，可以帮助它们平衡。 柔软的身体令学者很难将它们分类。 无腔动物非常细小，只长2毫米以下，没有消化道。 消化是由 …

2011年12月8日 · The Acoela is a small phylum which comprises approximately 400 species of small, mostly marine ‘worms’ that are completely ciliated. The acoels have an unquestioned monophyly and a well-documented phylogenetic position as one of the ‘basal’ metazoan groups.

2008年9月17日 · To investigate how the acoel mouth opening is related to the mouth and anus of protostomes and deuterostomes, we investigated the embryonic and juvenile expression of the genes that have been used...

2009年4月14日 · What are acoels? Acoels are small (less than 15 mm) soft-bodied, unsegmented worms. They live only in marine habitats and are found in all the world's oceans. They constitute their own clade ‘Acoela’, in which there are approximately 370 species. The name ‘acoel’ refers to their lack of a gut cavity as well as a coelomic cavity.

Acoela are found worldwide in mostly shallow waters in all oceans from tropical to polar regions. Habitat. Acoela live in marine or brackish water. Some species drift or swim in the open sea, or live unobtrusively among sand grains on sea bottoms in shallow coastal waters. Some even live in cold brine channels within Antarctic ice floes. Behavior

2012年9月29日 · Acoels are acoelomate, the space between gut and body wall being filled with parenchymal cells that occasionally contain chordoid vacuoles and the insunk bodies of epidermal and gland cells. The name ‘acoel’ comes from their lack of a …

2002年8月1日 · The order Acoela is a morphologically diverse group of small (∼0.5–10 mm long), soft-bodied, acoelomate worms found predominately in marine habitats. It is the major part of the Acoelomorpha (Acoela + Nemertodermatida), one of the three major clades in the phylum Platyhelminthes (see Smith et al., 1986 ).