Orthonectids
Scientific classification
Kingdom: Animalia Phylum: Orthonectida Giard, 1880

Orthonectida is a small phylum of poorly-known parasites of marine invertebrates that are among the simplest of multi-cellular organisms. Members of this phylum are known as orthonectids. Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Digimon, the only known animals. ... Charles Frédéric Girard (March 8, 1822 - January 29, 1895) was a French biologist specializing on ichthyology and herpetology. ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ...

Multinucleate plasmodia give rise to sexual males and females, which are free-swimming by means of cilia. They are composed of a single layer of ciliated outer cells surrounding a mass of sex cells. When a female is inseminated, the eggs develop into ciliated larvae that seek out new hosts and then break up into individual cells that become the next generation of plasmodia. cross-section of two cilia, showing 9+2 structure A cilium (plural cilia) is a fine projection from a eukaryotic cell that constantly beats in one direction. ...

Parasitized organisms include flatworms, polychaete worms, bivalve molluscs, and echinoderms. Classes Monogenea Trematoda Cestoda Turbellaria Wikimedia Commons has media related to: Platyhelminthes Wikispecies has information related to: Platyhelminthes The flatworms (Platyhelminthes, Greek platy: flat; helminth: worm) are a phylum of relatively simple soft-bodied invertebrate animals. ... Subclasses Palpata Scoleoida Tomopteris from plankton The Polychaeta or polychaetes are a class of annelid worms, generally marine. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ... Classes  ?Helicoplacoidea †  ?Arkarua †  ?Homalozoa † Eleutherozoa Asteroidea Concentricycloidea Echinoidea Holothuroidea Ophiuroidea Pelmatozoa Crinoidea Edrioasteroidea† Blastoidea † Cystoidea † Eocrinoidea † † = extinct Echinoderms . ...

The phylum consists of about 20 known species, of which Rhopalura ophiocomae is the best-known.

Originally described in 1880 as a class, and sometimes characterized as an order of Mesozoa, recent study shows that orthonectids are indeed quite different from rhombozoans, the other group in Mesozoa. Year 1880 (MDCCCLXXX) was a leap year starting on Thursday (link will display the full calendar). ... The Mesozoa are parasitic worm-like animals. ... Rhombozoa, or Dicyemida, is a phylum of tiny parasites that live in the renal appendages of cephalopods. ...

Known species:

• Family Rhopaluridae
  • Ciliocincta julini (Caullery and Mesnil, 1899) - E North Atlantic, in polychaetes
  • 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 paraphanostomae (Westblad, 1942) - E North Atlantic, in flatworms (Acoela)
  • 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, 1954) - Arctic Ocean, in gastropods (Lepeta, Natica, Solariella)
  • Rhopalura metschnikowi (Caullery and Mesnil, 1901) - E North Atlantic, in polychaetes and nemertines
  • Rhopalura murmanica (Shtein, 1953) - Arctic Ocean, in gastropods (Rissoa, Columbella)
  • Rhopalura ophiocomae (Giard, 1877) - E North Atlantic, in ophiuroids (usually Amphipholis)
  • Rhopalura pelseeneri (Caullery and Mesnil, 1901) - E North Atlantic, polychaetes and nemertines
  • Rhopalura philinae (Lang, 1951) - E North Atlantic, in gastropods
  • Rhopalura pterocirri (de Saint-Joseph, 1896) E North Atlantic, in polychaetes
  • Rhopalura variabili (Alexandrov and Sljusarev, 1992) - Arctic Ocean, in flatworms (Macrorhynchus)
  • Stoecharthrum giardi (Caullery and Mesnil, 1899) - E North Atlantic, in polychaetes
  • Stoecharthrum monnati (Kozloff, 1993) - E North Atlantic, in molluscs

• Family Pelmatosphaeridae
  • Pelmatosphaera polycirri (Caullery and Mesnil, 1904) - E North Atlantic, in polychaetes and nemertines

Wikispecies has information related to:

Orthonectida

Charles Frédéric Girard (March 8, 1822 - January 29, 1895) was a French biologist specializing on ichthyology and herpetology. ... Species Lineus alborostratus Lineus arenicola Lineus bicolor Lineus bilineatus Lineus corrugatus Lineus flavescens Lineus fuscoviridis Lineus longissimus Lineus ruber Lineus socialis Lineus torquatus Lineus viridis Lineus is a genus of nemertine worms, including the bootlace worm, arguably the longest animal alive. ... Families Actinoposthiidae Anaperidae Antigonariidae Antroposthiidae Childiidae Convolutidae Dakuidae Diopisthoporidae Hallangiidae Haploposthiidae Hofsteniidae Isodiametridae Mecynostomidae Nadinidae Otocelididae Paratomellidae Polycanthiidae Proporidae Sagittiferidae Solenofilomorphidae Taurididae Acoela is an order of animals treated either as a group of flatworms or as one of the two classes of the phylum Acoelomorpha, containing the majority of... Astarte on a car with four branches protruding from roof. ... Orders Oegophiurida Ophiurida Phrynophiurida Brittle stars are echinoderms, closely related to sea stars. ... GFDL Wikispecies logo File links The following pages link to this file: Solanaceae Species Asterias Homo (genus) Human Wikipedia:Template messages/Links Wikipedia:Template messages/All Homo floresiensis User talk:Tuneguru Template:Wikispecies Categories: GFDL images ... Wikispecies is a sister project supported by the Wikimedia Foundation that anybody can edit with a great potential use to students and researchers. ...

References

• Giard, E., "The Orthonectida, a new class of the phylum of the worms" Quart. J. Microsc. Sci., 1880 n.s. 20: 225-240
• Hanelt B, Van Schyndel D, Adema CM, Lewis LA, Loker ES, "The phylogenetic position of Rhopalura ophiocomae (Orthonectida) based on 18S ribosomal DNA sequence analysis", Mol Biol Evol. 1996 Nov;13(9):1187-91