Kingdom Animalia Order not assigned Rank Family | Class Acoela Phylum Xenacoelomorpha | |
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Similar Convolutidae, Isodiametridae, Convolutriloba, Polycanthus torosus | ||
Sagittiferidae is a family of Acoela.
Contents
Systematics
The family is divided into five genera (see taxobox) and contains about 20 species (Turbellarian taxonomic database, 2006). The affinities of the genera are as yet unclear. Some biologists prefer to exclude the genus Praesagittifera, leaving into the family only the genera with sagittocysts.
Characteristics
Sagittiferidae are small flat worm-like animals. Several of them grow symbiotic algae Tetraselmis in their body cavity and tissues.
Special characteristics include a ciliated or non-ciliated sac-like male antrum. Most members have sagittocysts on their skin. Sagittocysts are needle like bodies 18-50 µm long that contain some secretory product. They can be extruded from the body by an associated muscle. They are believed to play a role in defence and prey capture. Ultrastructurally, they have a vesicular core surrounded by a mesh of actin filaments.
Antrosagittifera
Contains the following species:
Convolutriloba
Contains the following species:
Sagittifera
Contains the following species:
Symsagittifera
Contains the following species: