Cycloneuralia is a clade of

ecdysozoan Ecdysozoa () is a group of protostome animals, including Arthropoda (insects, chelicerata, crustaceans, and myriapods), Nematoda, and several smaller phyla. They were first defined by Aguinaldo ''et al.'' in 1997, based mainly on phylogenetic t ...

animals including the

Scalidophora Scalidophora is a group of marine pseudocoelomate protostomes that was proposed on morphological grounds to unite three phyla: the Kinorhyncha, the Priapulida and the Loricifera. The three phyla have four characters in common — chitinous cu ...

(

Kinorhyncha Kinorhyncha ( grc, κινέω, kīnéō, I move, ' "snout") is a phylum of small marine invertebrates that are widespread in mud or sand at all depths as part of the meiobenthos. They are also called mud dragons. Modern species are or less, ...

ns, Loriciferans, Priapulids) and the

Nematoida Nematoida is a grouping of animals, including the roundworms The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known ...

( nematodes, Nematomorphs). It may be paraphyletic, or may be a sister group to

Panarthropoda Panarthropoda is a proposed animal clade containing the extant phyla Arthropoda, Tardigrada (water bears) and Onychophora (velvet worms). Panarthropods also include extinct marine legged worms known as lobopodians ("Lobopodia"), a paraphylet ...

. Or perhaps Panarthropoda is paraphyletic with respect to Cycloneuralia. The group has also been considered a single phylum, sometimes given the old name Nemathelminthes. The uniting character is the nervous system organization with a circumpharyngeal brain and somata–neuropil–somata pattern.The neuromuscular system of Pycnophyes kielensis (Kinorhyncha: Allomalorhagida) investigated by confocal laser scanning microscopy - EvoDevo
/ref> The name derives from the position of the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

around the

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its st ...

References

Ecdysozoa taxa Protostome unranked clades {{protostome-stub