Calcarea

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Calcarea

[kal′kar·ē·ə]
(invertebrate zoology)
A class of the phylum Porifera, including sponges with a skeleton composed of calcium carbonate spicules.

Calcarea

 

(or Calcispongiae), an order of marine invertebrate sponges. The skeleton of these sponges is formed from three-rayed, four-rayed, or uniaxial calcareous spicules. The structure of the canal system varies; all three types are encountered (ascon, sycon, and leucon). The Calcarea are small (usually no more than 7 cm high) individual or colonial animals. The body often has a tubular or barrel-like shape. The sponges live mainly in shallow waters. There are approximately 100 species in the order. There are more than ten species in the Soviet seas; the most common genera are Leucosolenia, Sycon, and Leucandra.

REFERENCES

Rukovodstvo po zoologii, vol. 1. Moscow-Leningrad, 1937.
Burton, M. A Revision of the Classification of the Calcareous Sponges.London, 1963.
References in periodicals archive ?
Ultrastructure and embryonic development of a syconoid calcareous sponge.
Furthermore, excellent images of phagocytosis by pseudopodia in the choanoflagellate Codosiga (Leadbeater and Morton, 1974) show that choanflagellates can generate equally long membrane extensions; similar pseudopodial extensions were described by de Saedeleer (1929), who also first suggested that calcareous sponges fed much like choanoflagellates.
So the larval release of this calcareous sponge is probably controlled by light cycles, as it is in certain demosponges (Amano, 1986, 1988; Maldonado and Young, 1996).
The calcareous sponge Leucosolenia laxa releases free-swimming coeloblastulae through the osculum with the excurrent water.
Dynamics and growth patterns of calcareous sponge spicules.
Sheath and axial filament of calcareous sponge spicules.
The coeloblastulae of calcareous sponges have been studied very rarely, and we know little about the process of their metamorphosis (Minchin, 1896; Tuzet, 1947; Borojevic, 1969).
laxa is one of the most common calcareous sponges in this region.
These cells form triradiates, a characteristic spicule of calcareous sponges, in the mesohyl of juvenile sponges.
In the coeloblastulae and amphiblastulae of calcareous sponges, however, the axonemes are probably shed soon after settlement (Amano and Hori, 1993).
In calcareous sponges, the consensus is that the choanocytes of juveniles derive from larval flagellated cells (Duboscq and Tuzet, 1937; Amano and Hori, 1993).