? Tongue worms
Linguatula taenioides, a pentastomid parasite of sheep. (Plate 17 of Curtice.[1])
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea Class: Maxillopoda Subclass: Pentastomida Diesing, 1836
Orders
Cephalobaenida Porocephalida Image File history File links Linguatula_taenioides. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anenomes) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (flatworms, echinoderms, etc. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - Trilobites (extinct) Subphylum Chelicerata Arachnida - Spiders, Scorpions, etc. ... Classes Remipedia Cephalocarida Branchiopoda Ostracoda Maxillopoda Malacostraca The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. ... Sub-classes Thecostraca Tantulocarida Branchiura Pentastomida Mystacocarida Copepoda Maxillopoda is a class of crustaceans, characterised by a reduction of the abdomen and its appendages. ...

The Pentastomida or Pentastoma are a group of parasitic invertebrates commonly known as tongue worms due to the resemblance of some species to a vertebrate tongue. For the rare minieral, see Parisite. ... Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... Many animals have longer and more flexible tongues than humans. ...

There are about 100 extant species of pentastomids; all are obligate parasites (i.e. they cannot live without their host) with correspondingly degenerate anatomy. Adult tongue worms parasitize the respiratory tracts of vertebrates. They have five anterior appendages: one is the mouth; the others are two pairs of hooks which they use to attach to the host. (This arrangement led to their scientific name, meaning "five openings", but although the appendages are similar in some species, only one is a mouth.) In humans the respiratory tract is the part of the anatomy that has to do with the process of respiration or breathing. ... Groups Conodonta Hyperoartia Petromyzontidae (lampreys) Pteraspidomorphi (early jawless fish) Thelodonti Anaspida Cephalaspidomorphi (early jawless fish) Galeaspida Pituriaspida Osteostraci Gnathostomata (jawed vertebrates) Placodermi Chondrichthyes (cartilaginous fish) Acanthodii Osteichthyes (bony fish) Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Tetrapoda Amphibia Amniota Sauropsida/(Reptiles) Aves (Birds) Synapsida Mammalia...

Their affinity with other invertebrates is uncertain. They grow by moulting, which suggests they belong to the Ecdysozoa. Historically they were considered to deserve a phylum of their own; however in 1972 Wingstrand showed similarities in the structure of spermatozoa between pentastomids and branchiurans (fish lice), a group of parasitic crustaceans,^[2] and this relationship is supported by molecular evidence.^[3] In birds, moulting or molting is the routine shedding of old feathers. ... The Ecdysozoa are a large group of protostomian animals, erected by Aguinaldo in 1997 primarily based on 18s rRNA data. ... Phylum (plural: phyla) is a taxon used in the classification of life, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... Schematic diagram of a sperm cell, showing the (1) acrosome, (2) cell membrane, (3) nucleus, (4) mitochondria, and (5) flagellum (tail) A sperm cell, or spermatozoon ( spermatozoa) (in Greek: sperm = semen and zoon = alive), is the haploid cell that is the male gamete. ... Branchiura is a group of parasitic crustaceans of uncertain position within the Maxillopoda. ... Classes Remipedia Cephalocarida Branchiopoda Ostracoda Maxillopoda Malacostraca The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. ...

However, fossils from the Upper Cambrian identified as pentastomids (Heymonsicambria, Haffnericambria, Bockelericambria) suggest that the pentastomids branched very early and may be an outgroup to the other arthropods.^[4] A fossil Ammonite Fossils are the mineralized or otherwise preserved remains — or other traces (such as footprints) — of animals, plants, and other organisms. ... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon and ended about 490 million years BP with the beginning of the Ordovician period. ...

Classification

This article follows Martin and Davis in placing Pentastomida in the class Maxillopoda within the subphylum Crustacea.^[5] Sub-classes Thecostraca Tantulocarida Branchiura Pentastomida Mystacocarida Copepoda Maxillopoda is a class of crustaceans, characterised by a reduction of the abdomen and its appendages. ... Classes Remipedia Cephalocarida Branchiopoda Ostracoda Maxillopoda Malacostraca The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. ...

Martin and David present this classification of the pentastomids down to the level of families:

Subclass Pentastomida Diesing, 1836

• Order Cephalobaenida Heymons, 1935
  • Cephalobaenidae Fain, 1961
  • Reighardiidae Heymons, 1935
• Order Porocephalida Heymons, 1935
  • Armilliferidae Fain, 1961
  • Diesingidae Fain, 1961
  • Linguatulidae Heymons, 1935
  • Porocephalidae Fain, 1961
  • Sambonidae Fain, 1961
  • Sebekiidae Fain, 1961
  • Subtriquetridae Fain, 1961

References

1. ^  Cooper Curtice (1890). The animal parasites of sheep, Washington: Government Printing Office.
2. ^  K. G. Wingstrand (1972). Comparative spermatology of a pentastomid, Raillietiella hemidactyli, and a branchiuran crustacean, Argulus foliaceus, with a discussion of pentastomid relationships. Kong. Danske Videnskabelige Selsk. Biol. Skrift. 19: 1–72.
3. ^  L. Abele, W. Kim, and B. E. Felgenhauer (1989). Molecular evidence for inclusion of the phylum Pentastomida in the Crustacea. Mol. Biol. Evol. 6: 685–691.
4. ^  D. Walossek and K. J. Müller (1998). "Cambrian "Orsten"-type arthropods and the phylogeny of Crustacea" R. A. Fortey and R. H. Thomas Arthropod Relationships, 139–143, London: Chapman & Hall.
5. ^  Joel W. Martin and George E. Davis (2001). An Updated Classification of the Recent Crustacea, Natural History Museum of Los Angeles County.