Tetrameridae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

spiruria Subclass Spiruria comprises mostly parasitic secernentean nematodes. In an alternate classification, they are treated as suborder Spirurina, with the orders listed here being ranked as infraorders. The Ascaridida and the Oxyurida, which includ ...

n nematodes. It is the smallest of the large genera making up the bulk of the

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Habronematoidea Habronematoidea is a superfamily of spirurian nematodes in the large order Spirurida. Like all nematodes, they have neither a circulatory nor a respiratory system. Though none of the families placed here are overly diverse, they are quite ...

. Like all nematodes, they have neither a

circulatory The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

nor a

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

. They are

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

s, chiefly of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s and cetaceans. This family contains the largest known nematode: ''

Placentonema gigantissima ''Placentonema gigantissima'' is a giant nematode that parasitizes the placenta of the sperm whale. With a length of and a diameter of , it is potentially the largest nematode worm ever described. It was discovered in the 1950s around the Kuril ...

'' is several meters long and has been found in the

placenta The placenta is a temporary embryonic and later fetal organ (anatomy), organ that begins embryonic development, developing from the blastocyst shortly after implantation (embryology), implantation. It plays critical roles in facilitating nutrien ...

of the

sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus '' Physeter'' and one of three extant species in the sperm whale famil ...

(''Physeter catodon'').

Systematics

The Tetrameridae number about half a dozen

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...

only, but some are rather speciose; the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nomina ...

Tetrameres ''Tetrameres'' is a genus of nematodes belonging to the family Tetrameridae Tetrameridae is a family (biology), family of spirurian nematodes. It is the smallest of the large genera making up the bulk of the Taxonomic rank, superfamily Habron ...

'' contains a lot of species even by nematode standards. While it might be overlumped, as presently delimited about half of the more than 100

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of Tetrameridae are placed in it. Subfamily Crassicaudinae Yorke & Maplestone, 1926 * '' Crassicauda'' Leiper & Atkinson, 1914 * ''

Placentonema ''Placentonema gigantissima'' is a giant nematode that parasitizes the placenta of the sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is th ...

'' Gubanov, 1951 Subfamily Geopetitiinae Chabaud, 1951 * '' Geopetitia'' Chabaud, 1951 iagnostic; French, Todd, Zachary & Meehan 1992 Subfamily Tetramerinae Travassos, 1914 * ''Microhadjelia'' Jogis, 1965 * ''Microtetrameres'' Travassos, 1915 * ''

'' Creplin, 1846

References

Spirurida Nematode families {{Secernentea-stub