4. Kingdom Animalia - part 02 - Phylum : Porifera

 

4. Kingdom Animalia - part 02 - Phylum : Porifera


Animal Classification :
1. Phylum : Porifera  ( pori-pores; feron-bearing) :


  • e.g. Scypha, Euspongia (Bath sponge), Euplectella (Venus' flower basket)
  • These are aquatic animals, most of them are marine and few are fresh water. They are also called 'sponges'.
  • Most of them have asymmetrical body.
  • Body of these animals consists of many cells with little division of labour. Hence their body is considered as a colony of different types of cells.
  • These are sedentary animals. 
  • On their body, they bear numerous minute pores called 'ostia' through which water enters in the body cavity- spongocoel. 
  • Water leaves the body through single large opening called 'osculum'.
  • Water is circulated in the body through the 'canal system'. 
  • During its circulation, cells of the animal body absorb food, exchange respiratory gases and release excretory products.
  • Spongocoel is lined by special flagellated cells called 'choanocytes' or 'collar cells'.
  • Beating of flagella creates water current. 
  • Body of these animals is supported by calcareous or siliceous 'spicules' or proteinaceous 'spongin fibers'.
  • They reproduce asexually as well as sexually. 
  • Asexual reproduction is performed by fragmentation and gemmule formation. 
  • These animals have ability of regeneration. 
  • Sexual reproduction is performed by formation of gametes. 
  • Fertilization is internal. 
  • Development takes place through indirect larval stage.

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