Hexactinellida


Also found in: Dictionary.
Related to Hexactinellida: Demospongiae

Hexactinellida

[hek‚sak·tə′nel·ə·də]
(invertebrate zoology)
A class of the phylum Porifera which includes sponges with a skeleton made up basically of hexactinal siliceous spicules.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Hexactinellida

 

(or Hyalospongia), a class of sponges. Hexactinellida are predominantly solitary, typically oceanic organisms, usually occurring at depths of more than 100 m, down to the hadal (or ultra-abyssal) zone. The body is saclike, tubular, goblet-shaped, or barrel-shaped, up to 2 meters in height. The skeleton consists of six-rayed siliceous spicules. The rays lie in three mutually perpendicular planes; in some of the needles, one or more rays are reduced. The canals that thread through the body wall (the canal system) are of the simple leuconoid type.

The class comprises about 500 species, 34 of which are found in the USSR—six in northern seas and 28 in Far Eastern seas. The most common are representatives of the genera Hyalonema, Aphrocallistes, Schaudinnia, Aulosaccus, Acanthascus, and Caulophacus.

The skeletons of some Hexactinellida are used for decorative purposes.

REFERENCES

Koltun, V. M. Stekliannye, ili shestiluchevye, gubki severnykh i dal’nevostochnykh morei SSSR. Leningrad, 1967. (Opredeliteli pofaune SSSR, vol. 94.)
Traité de zoologie, vol. 3, part 1. Edited by P.-P. Grassé. Paris, 1974. Page 687.

V. M. KOLTUN

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Collins, "Glass sponges (Porifera, Hexactinellida) of the northern Mid-Atlantic Ridge," Marine Biology Research, vol.
Menshenina, "Revision of the genus Asconema (Porifera: Hexactinellida: Rossellidae)," Journal of the Marine Biological Association of the United Kingdom, vol.
In situ feeding and metabolism of glass sponges (Hexactinellida, Porifera) studied in a deep temperate fjord with a remotely operated submersible.
The specimens of Aphrocallistes vastus [Schulze] (Porifera, Hexactinellida, Hexasterophora, Hexactinosida, Aphrocallistidae) were collected from Saanich Inlet and Barkley Sound, British Columbia (Canada) by scuba diving.
Second, the phylogenetic analyses confirm that, based on the autapomorphic character for Metazoa, the RTKs, sponges as a taxon are monophyletic; the Hexactinellida have been calculated to be the oldest class, followed by the Demospongia and finally by the Calcarea.
The Hexactinellida, for example, are mostly syncytial (Reiswig, 1979; Mackie and Singla, 1983), a condition that allows symplastic transport of food (Perez, 1996; Wyeth et al., 1996) and rapid conduction of action potentials that control the feeding current (Leys and Mackie, 1997).
Feeding in sponges has been well-documented, and with the exception of the two examples cited in the introduction, the Cladorhizidae and the Hexactinellida, particle uptake in sponges occurs at the choanocytes in the flagellated chambers or at the pinacoderm-lined incurrent canals.
Recent sponges generally have a skeleton made of spicules that are either siliceous (classes Demospongiae and Hexactinellida) or calcareous (class Calcarea).
Studies on the Hexactinellida. Contribution I (Euplectellidae).
In vitro aggregation of syncytia and cells of a Hexactinellida sponge.