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Symsagittifera schultzei (from Graff, 1891).png
Symsagittifera schultzei
Scientific classification
Kingdom: Animalia
Phylum: Xenacoelomorpha
Class: Acoela
Order: not assigned
Family: Sagittiferidae

Sagittiferidae is a family of Acoela.


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.[2]


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.[3] 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.[1] 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.



Contains the following species:


Contains the following species:


Contains the following species:


Contains the following species:


  1. ^ a b Gschwentner, Robert; Ladurner, Peter; Salvenmoser, Willi; Rieger, Reinhard; Tyler, Seth (1999), "Fine Structure and Evolutionary Significance of Sagittocysts of Convolutriloba longifissura (Acoela, Platyhelminthes)", Invertebrate Biology, American Microscopical Society, 118 (4): 332, doi:10.2307/3227005, JSTOR 3227005 
  2. ^ Achaz,J.G, Gschwentner,R, Rieger,R, "Symsagittifera smaragdina sp. nov.: A new acoel (Acoela: Acoelomorpha) from the Mediterranean Sea", Zootaxa 1085: 33-45, 2005
  3. ^ Kostenko,A.G, Mamkaev,Y.V. "The position of "green convoluts" in the system of acoel turbellarians (Turbellaria, Acoela). 1. Simsagittifera gen. n. 2. Sagittiferidae fam. n", Zool Zh 69(6):11-21,1990