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 .

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).

Acoelomorpha is a subphylum of very simple and small soft-bodied animals with planula -like features which live in marine or brackish waters. They usually live between grains of sediment, swimming as plankton, or crawling on other organisms, such as algae and corals. [1] .

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.

Acoela are free-living, either planktonic (swimming or drifting) or interstitial (living between sand grains on the sea bottom). A few are commensals on other invertabrates. They move by means of cilia, or tiny hairlike projections, covering the entire outer side of their epidermis.

Order Acoela Exclusively marine; mouth present; pharynx simple or lacking; no intestine; without protonephridia, oviducts, yolk glands, or definitely delimited gonads; about 200 species.

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.

The Acoela or acoels are a class of small and simple invertebrates in the phylum Xenacoelomorpha that resemble flatworms. Historically they were treated as an order of turbellarian flatworms, but molecular phylogeny studies revealed them to be basal bilaterians.

2012年9月29日 · 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).

Acoels (AY-seels) are tiny wormlike sea animals. They are the simplest animals with bilateral symmetry (bye-LAT-er-uhl SIH-muh-tree), meaning the right and left halves of the body match each other.