Orthonectida

**Orthonectida** iku filum kecil parasit ora digelet pengertiané sekang invertebrata sagara sing salah siji organisme multiselular sing paling biyasa.

## Biologi 
Gedene iku kéwan kaya cacing mikroskopis, sing lewih sekang siji lapisan sel njaba ana siliané sekitaré massa sel kelaminé. Kae rénang karo bébas ing tubuh inangé, sing kelebu platyhelminthes, cacing polychaeta, moluska bivalvia, lan echinodermata. Kae gonochoristic, karo individu lanang lan wadon misah.

Angger wis siyap kanggo réproduksi, kae lunga sekang inangé, lan sperma sekang lanang nembus awak sing wadon kanggo fertilisasi internal. Zigot sing dikasilna dadi larva ngabi silia sing lolos sekang biyungé kanggo nggolet inang anyar. Bar nemu inang, larva kelangan silia lan dadi larva plasmodium syncytial. Larva iki, gilirané, mecah dadi akèh sel-sel individual sing arep dadi génerasi selanjute. lan kadang-kadang ditandai kanggo ordho ing filum Mesozoa, panalitèn anyar, orthonectids béda pisan karo rhombozoa, kelompok lain di Mesozoa.

Spesies sing wis katon:

Filum **Orthonectida**
* Famili Rhopaluridae Stunkard, 1937
** *Ciliocincta akkeshiensis* Tajika, 1979 – Hokkaido, Japan; in flatworms (Turbellaria)
** *Ciliocincta julini* (Caullery and Mesnil, 1899) – E North Atlantic, in polychaetes
** *Ciliocincta sabellariae* Kozloff, 1965 – San Juan Islands, WA (USA); in polychaete (*Neosabellaria cementarium*)
** *Intoshia leptoplanae* Giard, 1877 – E North Atlantic, in flatworms (*Leptoplana*)
** *Intoshia linei* Giard, 1877 – E North Atlantic, in nemertines (*Lineus*) = *Rhopalura linei*
** *Intoshia major* Shtein, 1953 – Arctic Ocean; in gastropods (*Lepeta*, *Natica*, *Solariella*) = *Rhopalura major*
** *Intoshia metchnikovi* (Caullery & Mesnil, 1899) – E North Atlantic, in polychaetes and nemertines
** *Intoshia paraphanostomae* (Westblad, 1942) – E North Atlantic, in flatworms (*Acoela*)
** *Intoshia variabili* (Alexandrov & Sljusarev, 1992) – Arctic Ocean, in flatworms (*Macrorhynchus*)
** *Rhopalura elongata* Shtein, 1953 – Arctic Ocean, in bivalves (*Astarte*)
** *Rhopalura gigas* (Giard, 1877)
** *Rhopalura granosa* Atkins, 1933 – E North Atlantic, in bivalves (*Pododesmus*)
** *Rhopalura intoshi* Metchnikoff – Mediterranean, in nemertines
** *Rhopalura litoralis* Shtein, 1953 – Arctic Ocean, in gastropods (*Lepeta*, *Natica*, *Solariella*)
** *Rhopalura major* Shtein, 1953
** *Rhopalura murmanica* Shtein, 1953 – Arctic Ocean, in gastropods (*Rissoa*, *Columbella*)
** *Rhopalura ophiocomae* Giard, 1877 – E North Atlantic, in ophiuroids (usually *Amphipholis*)
** *Rhopalura pelseneeri* Caullery & Mesnil, 1901 – E North Atlantic, polychaetes and nemertines
** *Rhopalura philinae* Lang, 1954 – E North Atlantic, in gastropods
** *Rhopalura pterocirri* de Saint-Joseph, 1896 – E North Atlantic, in polychaetes
** *Rhopalura vermiculicola*
** *Stoecharthrum burresoni* Kozloff, 1993
** *Stoecharthrum fosterae* Kozloff, 1993
** *Stoecharthrum giardi* Caullery & Mesnil, 1899 – E North Atlantic, in polychaetes
** *Stoecharthrum monnati* Kozloff, 1993 – E North Atlantic, in molluscs
* Famili Pelmatosphaeridae Stunkard, 1937
** *Pelmatosphaera polycirri* Caullery and Mesnil, 1904 – E North Atlantic, in polychaetes and nemertines

## Préferensi