Rhabditia

Last updated

Rhabditia
Hookworms.JPG
Ancylostoma caninum hookworms
(Strongylida: Ancylostomidae)
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Subclass: Rhabditia
Orders

Rhabditida
Strongylida
and see text

Synonyms

Rhabditina

Subclass Rhabditia is mostly composed of parasitic nematodes (particularly in the Strongylida), though there are some free-living species as well (particularly in the Rhabditida). Phasmids (posterior sensory structures) are well-developed, while amphids (anterior sensory structures) are poorly developed or absent in this group.

In an alternate classification system, they are treated as suborder Rhabditina, with the orders listed here being ranked as infraorders. Also, the Diplogasterida, which are sometimes considered a monotypic subclass, are probably better placed in the Rhabditia. On the other hand, the old placement of the Ascaridida in Rhabditia instead of Spiruria seems unwarranted. The Rhabditida contain a number of families which are probably better placed in the Tylenchia; alternatively, the latter group may entirely be merged with the Rhabditia. [1]

See also

Related Research Articles

Alismatales Order of herbaceous flowering plants of marshy and aquatic habitats

The Alismatales (alismatids) are an order of flowering plants including about 4500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats.

Apicomplexa A phylum of parasitic alveolates

The Apicomplexa are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of plastid called an apicoplast, and an apical complex structure. The organelle is an adaptation that the apicomplexan applies in penetration of a host cell.

Cucurbitales Order of flowering plants

The Cucurbitales are an order of flowering plants, included in the rosid group of dicotyledons. This order mostly belongs to tropical areas, with limited presence in subtropic and temperate regions. The order includes shrubs and trees, together with many herbs and climbers. One major characteristic of the Cucurbitales is the presence of unisexual flowers, mostly pentacyclic, with thick pointed petals. The pollination is usually performed by insects, but wind pollination is also present.

Euglenozoa Phylum of protozoans

The euglenozoa are a large group of flagellate Excavata. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. There are two main subgroups, the euglenids and kinetoplastids. Euglenozoa are unicellular, mostly around 15–40 μm (0.00059–0.00157 in) in size, although some euglenids get up to 500 μm (0.020 in) long.

Arachnid Class of arthropods

Arachnida is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes orders containing spiders, scorpions, ticks, mites, harvestmen, and solifuges. In 2019, a molecular phylogenetic study also placed horseshoe crabs in Arachnida.

Amniote Clade of tetrapods including reptiles, birds and mammals

Amniotes are a clade of tetrapod vertebrates comprising the reptiles and mammals. Amniotes lay their eggs on land or retain the fertilized egg within the mother, and are distinguished from the anamniotes, which typically lay their eggs in water. Older sources, particularly prior to the 20th century, may refer to amniotes as "higher vertebrates" and anamniotes as "lower vertebrates", based on the discredited idea of the evolutionary great chain of being.

Ranunculales Basal order of flowering plants in the eudicots

Ranunculales is an order of flowering plants. Of necessity it contains the family Ranunculaceae, the buttercup family, because the name of the order is based on the name of a genus in that family. Ranunculales belongs to a paraphyletic group known as the basal eudicots. It is the most basal clade in this group; in other words, it is sister to the remaining eudicots. Widely known members include poppies, barberries, and buttercups.

Hydrozoa A class of cnidarians

Hydrozoa are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most living in salt water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genera within this class live in fresh water. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria.

Pauropoda Class of arthropods

Pauropods are small, pale, millipede-like arthropods. Around 830 species in twelve families are found worldwide, living in soil and leaf mould. They look rather like centipedes, but are probably the sister group to millipedes.

Pterygota Subclass of insects

The Pterygota are a subclass of insects that includes the winged insects. It also includes insect orders that are secondarily wingless.

Gleicheniales

Gleicheniales is an order of ferns in the subclass Polypodiidae. The Gleicheniales appeared in the fossil record at least as early as the Cretaceous.

Ascaridida Order of parasitic roundworms

The order Ascaridida includes several families of parasitic roundworms with three "lips" on the anterior end. They were formerly placed in the subclass Rhabditia by some, but morphological and DNA sequence data rather unequivocally assign them to the Spiruria. The Oxyurida and Rhigonematida are occasionally placed in the Ascaridida as superfamily Oxyuroidea, but while they seem indeed to be Spiruria, they are not as close to Ascaris as such a treatment would place them. These "worms" contain a number of important parasites of humans and domestic animals.

Secernentea Class of roundworms

Secernentea was a class of nematodes in the Classical Phylogeny System and is no longer in use. This morphological-based classification system has been replaced by the Modern Phylogeny system, where taxonomy assignment is based on small subunit ribosomal DNA.

<i>Canadaspis</i>

Canadaspis is an extinct genus of Cambrian-aged crustacean or euarthropod, a benthic feeder that moved mainly by walking and possibly used its biramous appendages to stir mud in search of food. The genus has been placed within the subclass Phyllocarida, in the class Malacostraca that includes shrimps and lobsters.

Fish Vertebrate animal that lives in water and usually has gills

Fish are gill-bearing aquatic craniate animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Around 99% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with over 95% belonging to the teleost subgrouping.

Chromadorea Class of roundworms

The Chromadorea are a class of the roundworm phylum, Nematoda. They contain a single subclass (Chromadoria) and several orders. With such a redundant arrangement, the Chromadoria are liable to be split up if the orders are found to form several clades, or abandoned if they are found to constitute a single radiation.

Spiruria Subclass of roundworms

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.

Trachylinae A subclass of hydrozoans

Trachylinae is a subclass of hydrozoans. It is placed at order rank in many older classifications, and limited to contain the Narcomedusae and Trachymedusae. But the Actinulidae, then considered an independent order, and probably also the Limnomedusae which were traditionally placed in the paraphyletic "Hydroida", belong to this group too. It is not entirely clear whether the Limnomedusae and the Trachymedusae as conventionally circumscribed are monophyletic

Nematode A phylum of worms with tubular digestive systems with openings at both ends

The nematodes or roundworms constitute the phylum Nematoda, with plant-parasitic nematodes being known as eelworms. They are a diverse animal phylum inhabiting a broad range of environments. Taxonomically, they are classified along with insects and other moulting animals in the clade Ecdysozoa, and unlike flatworms, have tubular digestive systems with openings at both ends. Like tardigrades they have a reduced number of Hox genes, but as their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, it shows that the reduction has occurred within the nematode phylum.

Yinotheria

Yinotheria is a proposed basal subclass clade of crown mammals that contains a few fossils of the Mesozoic and the extant monotremes. Today, there are only five surviving species, which live in Australia and New Guinea, but fossils have been found in England, China, Russia, Madagascar and Argentina. The surviving species consist of the platypus and four species of echidna. Contrary to other known crown mammals, they retained postdentary bones as shown by the presence of a postdentary trough. The extant members (monotremes) developed the mammalian middle ear independently.

References

  1. Tree of Life Web Project (ToL) (2002b): Nematoda. Version of 2002-JAN-01. Retrieved 2008-NOV-02.ToL (2002)