Sponges.
The poríferos, called also sponges for the presence of numerous pores in all his bodies, are animal, because his level of organization, which reaches, which does not overcome the mystical level, that is to say, possesses differentiated textiles, peros this they do not gather together to form organs. With frequencies it appears without a definite symmetry, and they lack nervous cells and muscular organized fibers.
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All the sponges are aquatic, since they are marine or dulcecuícolas, they form to tripes colonies, live in waters next to the shores, but also in the abysmal depths, both in cold and warm regions. The body of the sponges there is formed by a gelatinous textile trasparente, the mesogleas, in that one finds food particles dispersed in diverse types of fagocitar; the escleroblastos, which generate the elements of support; and the arqueocitos, undifferentiated, that take part in the regeneration of the lost parts of the animal, in this mass appear also a structure of support in the shape of needles, the espículas, of composition variable, the reproductive cells or gonocitos; and a few contractile cells the miocitos, which usually gather together about the osculation.
The sponges possess skeletons formed for espículas of lime or silica and that is an important characteristic for his classification
The sponges reproduce vegetativamente by means of gemación, production of egg yolks in the body of the adult, who after a time becomes detached and develop, to produce a few new individuals. They are characterized also by his extraordinary capacity of regeneration, which allows them to reconstruct big part of the body when they lose it, the sexual reproduction takes place for merger of ova and spermatozoids generated by the gonocitos, almost all the species they are hermaphrodite, but each of the sexes matures in different epochs.
According to his structures, three principal types of sponges can differ: ascon, sycon and leucon.
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Those of guys Ascon.
They are them simpler, species of sacks are formed by one with a central cavity, the gastric cavity, which is opened on the outside across a gap called osculation and is re-dressed of coanocitos, flagellated special cells.
The guys Syscon, the coanocitos do not get ready in the gastric cavity, but in a few channels, which they communicate to this one with the exterior.
Guys Syscon
The Leucon.
These channels expand the coanocitos, the systematical one of the poríferos it distinguishes the classes, which are described next:
Calcareous sponges.
The espículas of this one sponges are calcareous, and they have form of needles of 3 or 4 radioes, the surfaces of the body it is usually shaggy, his coloring is extinguished and they usually measure less than 15 cm, they are all marinas and they are represented by Leucoselenia.
Sponges Silíceas.
Plains also hexactinélidas, his espículas are formed for silíce and it has six radioes. There are separated or joined formed networks, which sometimes look like a glass textile, are exclusively marine and they live between the 100 and the 6000 of meters of depth, his body is usually lengthened or in the shape of funnel and measures up to a meter long, as the Filipinos' sprinkling can.
This is a partial list of the marine sponges and of fresh water of Venezuela Image edited for
Demosponjas.
Acquaintances as typical sponges, have the skeletons formed for espículas corneas, for espículas silíceas (but that never has síes radio, as in the glassy sponges, for both substances or simply they lack skeleton, look alike many to the sponges of baths. Some sponges possess simbiontes photosynthetics (cianobacterias, zooxantelas, diatomeas, zooclorelas) or not (bacteria). Periodically they expel the simbiontes and cells somáticas, and secrete mucous substances regularly. In certain sponges the simbiontes go so far as to represent 38 % of his corporal volume.
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