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 ?
Diet composition of two temperate calcareous sponges: Leucosolenia echi-nata and Leucetta sp.
Calcareous sponges make up only 5% of all Porifera and are the only group with ascon (choanocyte-lined tubes) and sycon (long choanocyte-lined chambers branching off a central cavity) as well as leucon body plans.
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.
The flagellated cells in the coeloblastulae of calcareous sponge s cannot, however, be discarded, because these cells make up the greater part of the larva.
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.
An amphiblastula or coeloblastula is produced by calcareous sponges; a parenchymella is the larva of the majority of demosponges, but several other larval types are known; and a trichimella is exclusive to hexactinellid sponges.
domuncula 1300 ([k.sub.aa]-value of 0.84) and the calcareous sponge S.
In the amphiblastula larvae of calcareous sponges, flagellated cells shed and discard their excised flagella (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).