What is "articulata"

Encrinoidea \En`cri*noid"e*a\, n. pl. [NL. See Encrinus and -oid.] (Zo["o]l.) That order of the Crinoidea which includes most of the living and many fossil forms, having jointed arms around the margin of the oral disk; -- also called Brachiata and Articulata. See Illusts. under Comatula and Crinoidea. [1913 Webster] ||

Articulata \Ar*tic`u*la"ta\ ([aum]r*t[i^]k`[-u]*l[=a]"t[.a]), n. pl. [Neut. pl. from L. articulatus furnished with joints, distinct, p. p. of articulare. See Article, v.] (Zo["o]l.)

1. One of the four subkingdoms in the classification of Cuvier. It has been much modified by later writers.

   Note: It includes those Invertebrata having the body composed of a series of ringlike segments (arthromeres). By some writers, the unsegmented worms (helminths) have also been included; by others it is restricted to the Arthropoda. It corresponds nearly with the Annulosa of some authors. The chief subdivisions are Arthropoda (Insects, Myriapoda, Malacopoda, Arachnida, Pycnogonida, Crustacea); and Anarthropoda, including the Annelida and allied forms.

2. One of the subdivisions of the Brachiopoda, including those that have the shells united by a hinge.

3. A subdivision of the Crinoidea.

Articulata is a Latin word meaning articulated or jointed. In taxonomy, it is used to refer to various subdivisions.

It may refer to:

• Articulata (Brachiopoda), one of two main divisions of the brachiopods having two valves with an articulating hinge
• Articulata (Crinoidea), a subclass of crinoids, the only such to survive past the Paleozoic era
• Articulata (Cyclostomata), a group of cyclostome bryozoans, also known as Articulina
• Articulata hypothesis, a hypothesis treating Annelida and Panarthropoda as sister taxa

Articulata are the only extant subclass of the class Crinoidea. The group includes "sea lilies" and "feather stars". The Articulata are differentiated from the extinct subclasses by their lack of an anal plate in the adult stage and the presence of an entoneural system. Articulata are stalked echinoderms with pentamerous symmetry. The stalk, which consists of numerous disks held together by ligaments, supports a calyx or cup made of circlets of calcerous plates. In Comatulids, the stalk develops following the larval stage, but the juveniles shed all but the topmost disk to take up a free-living existence. Five often branched arms, which consist of articulated series of ossicles, extend from the oral plate and form the food-capture mechanism of Articulata. The arms of Articulata are pinnulate in that they have alternating pinnules branching out along them to effectively increase the surface area for feeding. These pinnules all have ciliated ambulacral grooves that converge to form larger grooves in the arms that lead down to the mouth located beside the anus on the upper surface of the oral plate. Articulata are passive suspension feeders. They capture algae with triplets of tube feet located on the pinnules, and the ciliated ambulacral canals transport this algae to the mouth. Although they are passive feeders, some Articulata have been observed to move to better feeding areas either with locomotory mechanisms at the base of the stalk or by detaching and pulling themselves with their arms. Currently there are 540 described species of Articulata that fall into two major orders. The bourgueticrinids which have the traditional stalked body form account for about 15% percent of the known species while the comatulids are unstalked and account for most of the rest.

The Articulata is a class of brachiopods which comprises those with hinged, calcareous shells that generally bear well developed teeth and sockets and a simple muscle system. The name was first applied to this major group of brachiopods by Huxley in 1869, ten years prior to Zittel choosing the same name in 1879 for modern crinoids.

The Articulata has been replaced by the Subphylum Rhynchonelliformea which except for taxonomic rank and revision of some taxa within, is essentially synonymous.

Moore, Lalicker, and Fischer, 1952, divided the Articulata into the following groups:

• Paleotremata
• Orthida
• Terebratulida
• Pentamerida
• Rhynconellida
• Strophomenida
• Spiriferida

The earlier version of the Treatise, part H, 1965, is similar, except for the elimination of the Paleotremata and the order in which the remaining orders are presented.