All Jharkhand Competitive Exam JSSC, JPSC, Current Affairs, SSC CGL, K-12, NEET-Medical (Botany+Zoology), CSIR-NET(Life Science)

Thursday, October 1, 2020

Phylum - Porifera - NEET-Biology

 Phylum Porifera

Fig: Phylum Porifera = Pore Bearing

Important Characteristics:

  • Sponges are primitive multicellular animals with a cellular grade of organization. 
  • They have no fixed body shape & no plane of symmetry. 
  • Whole sponges can be regenerated from a few separated cells.
  • Sponges are free-living aquatic (mostly marine) & having neither nerves nor muscles.
  • Body wall with two layers of loosely arranged cells and mesenchyme in between (diploblastic).
  • Reproduction occurs by asexual (external & internal buds) or sexual methods.
  • The body-wall encloses a large cavity, the spongocoel & in most cases also contain numerous small canals. 
  • The ceaseless beating of flagella maintains s steady current of water through the canals to bring in food & oxygen & remove waters.
  • Almost all sponges possess an internal skeleton. It may consist of tiny siliceous spicules or of fine spongin fibers or of both.
  • Example: Sycon (Scypha), Spongilla (Freshwater sponge), Euspongia (Bath sponge)



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