an extensive artificial group of invertebrates, having all the parts arranged radially around the vertical axis of the body, and the various organs repeated symmetrically in each ray or spheromere
Origin: [NL., fr. radiatus, p. p. See Radiate.]
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 cnidarians 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. 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.
Chambers 20th Century Dictionary
rā-di-ā′ta, n.pl. the lowest of Cuvier's four great divisions of the animal kingdom—the organs of sense and motion disposed as rays round a centre.
The numerical value of radiata in Chaldean Numerology is: 5
The numerical value of radiata in Pythagorean Numerology is: 9
Images & Illustrations of radiata
Find a translation for the radiata definition in other languages:
Select another language: