Hemichordata

[¦he·mē·kȯr′däd·ə]

(systematics)

A group of marine animals categorized as either a phylum of deuterostomes or a subphylum of chordates; includes the Enteropneusta, Pterobranchia, and Graptolithina.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Hemichordata

a phylum of bottom-dwelling marine invertebrates of the group Deuterostomata. The Hemichordata were previously considered a subphylum of Chordata because of the presence of a chordlike organ (notochord), the dorsal location of the nerve stem, the development of gill slits, and several similar features of embryonic development. However, unlike the chordates, hemichordates have a three-segmented body consisting of a proboscis, collar cavities, and trunk cavities. Modern-day hemichordates are the Enteropneusta and Pterobranchia; fossil representatives include the graptolites.

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References in periodicals archive

1928 242,126 Hemichordata Balanoglossus aurantiaca Girard, 1853 143,815 Cephalodisctts gracilis Harmer, 1905 57,139 Cephalodiscus hodgsoni Ridewood, 1907 200,052 Cephalodiscus nigrescens Lankester, 1905 11.565 Harrimaniidae gen sp.

Discovery of Novel Hemocyanin-Like Genes in Metazoans

V: Smaller Coelomate Groups--Chaetognatha, Hemichordata, Pogonophora, Phoronida, Ectoprocta, Brachiopoda, Sipunculida.

Braquiopodos, sipunculidos, enteropneustos y metales en dos planicies estuarinas de marea, Pacifico, Costa Rica

Two of them are possible ancestral states in Hemichordata and Echinodermata.

The evolutionary relationship between microbial rhodopsins and metazoan rhodopsins

Molecular phylogeny of hemichordata, with updated status of deep-sea enteropneusts.

A new copepod with transformed body plan and unique phylogenetic position parasitic in the acorn worm Ptychodera flava

Taxa 18S rDNA 16S rDNA HEMICHORDATA Cephalodiscidae Cephalodiscus hodgsoni KF683576 -- HI 1.3 Cephalodiscus hodgsoni EU728441 -- Cephalodiscus fumosus KF83575 -- H5.3 Cephalodiscus KF683574 -- nigrescens H12.3 Cephalodiscus gracilis AF236798 -- Cephalodiscus densus EU728439 -- Cephalodiscus EU728440 -- nigrescens Rhabdopleuridae Rhabdopleura sp.

Hemichordate Molecular Phylogeny Reveals a Novel Cold-Water Clade of Harrimaniid Acorn Worms

This is the first clear instance of external brooding ever found in the phylum Hemichordata.

An externally brooding acorn worm hemichordata, enteropneusta, torquaratoridae from the Russian Arctic

221-347 in Microscopical Anatomy of Invertebrates: Hemichordata, Chaetognatha and the Invertebrate Chordates, Vol.

Continued growth and cell proliferation into adulthood in the notochord of the appendicularian Oikopleura dioica

1, Hemichordata, Chaetognatha, and the Invertebrate Chordates, G.

Endogenous green fluorescent protein (GFP) in amphioxus

Nervous system of the tornaria larva (Hemichordata, Enteropneusta).

Time and extent of ciliary response to particles in a non-filtering feeding mechanism

Structure of the nervous system in the tornaria larva of Balanoglossus proterogonius (Hemichordata: Enteropneusta) and its phylogenetic implications.

The larval apical organ in the holothuroid Chiridota gigas (Apodida): inferences on evolution of the ambulacrarian larval nervous system

Structure, ultrastructure, and function of the preoral heart-kidney in Saccoglossum kowalevskii (Hemichordata: Enteropneusta) including new data on the stomochord.

Undifferentiated cells in the snail myocardium are capable of DNA synthesis and myodifferentiation

The deuterostome phylum Hemichordata is composed of three extant classes: the Enteropneusta are solitary worms, the Pterobranchia are colonial tube-dwelling suspension feeders, and the Planktosphaeroidea are known only from their larvae.

The anatomy, life habits, and later development of a new species of enteropneust, Harrimania planktophilus (hemichordata: Harrimaniidae) from barkley sound