Radiata

Radiata is a taxonomic rank that has been used to classify radially symmetric animals. The term Radiata has united several different groupings of animals, none of which form a monophyletic group under current views of animal phylogeny. Because of this and problems of homoplasy associated with this character, the term is used mostly in a historical context.

In the early 19th century, Georges Cuvier united ctenophores and cndarians in the Radiata. Thomas Cavalier-Smith, in 1983, redefined Radiata as a subkingdom consisting of Porifera, Myxozoa, Placozoa, Cnidaria and Ctenophora. Lynn Margulis and K. V. Schwartz later redefined Radiata in their Five Kingdom classification, this time including only Cnidaria and Ctenophora.

Although radial symmetry is usually given as a defining characteristic in animals that have been classified in this group, there are clear exceptions and qualifications. Echinoderms, for example, exhibit unmistaken bilateral symmetry as larvae. Ctenophores exhibit biradial or rotational symmetry, defined by tentacular and pharyngeal axes, on which two anal canals are located in two diametrically opposed quadrants. Some species within the cnidarian class Anthozoa are bilaterally symmetric (For example, Nematostella vectensis). It has been suggested that bilateral symmetry may have evolved before the split between Cnidaria and Bilateria, and that the radially symmetrical cnidarians have secondarily evolved radial symmetry, meaning the bilaterality in cnidarian species like N. vectensis have a primary origin.

Other articles related to "radiata":

Pterois Radiata
... Pterois radiata, also known as the Clearfin Lionfish, Tailbar Lionfish, Radiata Lionfish or Radial Firefish, is a carnivorous, ray-finned fish with venomous spines ...
Corona Radiata
... In neuroanatomy, the corona radiata is a white matter sheet that continues ventrally as the internal capsule and dorsally as the centrum semiovale ... The corona radiata is associated with the corticospinal tract, the corticopontine tract, and the corticobulbar tract ...
Lycoris (plant) - Gallery
... Lycoris aurea, a species with long stamens Lycoris aurea (yellow) and Lycoris radiata (red) in Chiba Japan Lycoris radiata is an important cultural icon in Japan Lycoris squamigera, a species with short ...
Cellana - Species
... Cellana pricei Cellana radians Cellana radiata Cellana radiata capensis Cellana radiata cylindrica Cellana radiata enneagona Cellana radiata orientalis Cellana radiata radiata ...