There is a great controversy regarding the origin of Porifera. The Porifera may be defined as “asymmetrical or radially symmetrical multicellular organisms with cellular grade of organisation without well-defined tissues and organs exclusively aquatic mostly marine, sedentary, solitary or colonial animals with body perforated by pores, canals and chambers through which water flows with one or more internal cavities lined with choanocytes and with characteristic skeleton made of calcareous spicules, siliceous spicules or horny fibres of spongin”. Sponges are cultivated for commercial purposes.Īpproximately 10,000 species of sponges are known at present, and the phylum is divided into three classes, viz., Calcarea or Calcispongiae, Hexactinellida or Hyalospongiae, and Demospongiae and about twelve orders chiefly on the type of skeleton. Because of their endoskeleton and obnoxious ferments they are generally not eaten by animals. They usually have an endoskeleton of separate spicules.ĭigestion takes place within the cells. Though sponges are multicellular animals their cells do not form organised tissues. The body is perforated by pores and canals but there are no organs, such as mouth or nervous system. Their shape may be cylindrical, branching,vase-like or globular, some are dull in colour but most are brightly coloured, they have red, orange, purple, green or yellow colour. As a result Linnaeus, Lamarck, and classified the sponges under zoophytes or polyps and regarded them as allied to anthozoan coelenterates. The nature of sponges was debated until well into the nineteenth century, although evidence of their animal nature was given in 1765 by who saw the water currents and movements of the oscula. The name Porifera (L., porus = pore ferro = to bear) comes from (1836). In this article we will discuss about Sponges:- 1.
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