![]() ![]() The cavity is lined by flattened cells of ectodermal origin, the pinacocytes. The Para gastric cavities or spongocoels of different branches in a colonial form, are in communication with one another through a broad chamber at the base. Osculum leads internally into a canal, the spongocoel, which runs along the middle of the branch and receives a large number of ex-current canals of the branch. Absence of true tissues and extensive system of pores and canals powered by the action of peculiar flagellated cells, the choanocytes, make them distinct from other metazoan.Īt the free end of a branch, a fairly large aperture known as osculum is present. They are distinct from the Protozoa in having a cellular construction but the cellular grade is at the lowest. Sponges are of varying shapes, sizes and colours. They grow mainly in shallow waters but their habitat may extend up to a depth of 5,600 metres. Of the described sponges, about 5,000 species are marine and very few are fresh water. parous = pore + ferre = bear) or sponges are lowly organised group of plant-like sessile animals remaining attached to the substratum. Classification: Phylum Porifera or Sponges.Reproduction and Development in the Sponges.Histological Elements Constituting the Wall of Sponges.In this article we will discuss about:- 1. ![]()
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