In biological classification , class ( Latin : classis ) is a taxonomic rank , as well as a taxonomic unit, a taxon , in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are life , domain , kingdom , phylum , order , family , genus , and species , with class ranking between phylum and order.
6-427: See text . Caudofoveata is a small class within the phylum Mollusca , also known as Chaetodermomorpha . The class is often combined with Solenogastres and termed Aplacophora , but some studies have cast doubt on the monophyly of this group. Caudofoveata are worm-like molluscs ranging 0.02–10 cm in size, but one species, Chaetoderma felderi, can reach 36.5 cm. The foot is completely absent, and instead of
12-463: A convenient "artificial key" according to his Systema Sexuale , largely based on the arrangement of flowers. In botany, classes are now rarely discussed. Since the first publication of the APG system in 1998, which proposed a taxonomy of the flowering plants up to the level of orders, many sources have preferred to treat ranks higher than orders as informal clades . Where formal ranks have been assigned,
18-412: A general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct grade of organization—i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs—with a distinct type of construction, which is to say a particular layout of organ systems. This said, the composition of each class
24-494: A shell their mantle is covered in calcareous spines called sclerites . Caudofoveates live by burrowing through soft sediment, and feed by lying vertically in the sediment with just the mouthparts exposed and taking in passing organic detritus. During sexual reproduction , the female produces eggs which are fertilized and brooded, and then the larvae swim freely. Caudofoveates are deposit feeders, or more selective detritivores or predators of foraminifera . Caudofoveata comprises
30-431: Is ultimately determined by the subjective judgment of taxonomists . In the first edition of his Systema Naturae (1735), Carl Linnaeus divided all three of his kingdoms of nature ( minerals , plants , and animals ) into classes. Only in the animal kingdom are Linnaeus's classes similar to the classes used today; his classes and orders of plants were never intended to represent natural groups, but rather to provide
36-441: The following families and genera: There are 15 genera, with about 150 known species. Class (biology) The class as a distinct rank of biological classification having its own distinctive name – and not just called a top-level genus (genus summum) – was first introduced by French botanist Joseph Pitton de Tournefort in the classification of plants that appeared in his Eléments de botanique of 1694. Insofar as
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