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What is Phylum Porifera?

Porifera or Sponges

• The lowest or the simplest multicellular animals are called Porifera. They are commonly called Sponges.
• They neither possess any specialised body structure nor any tissues or organs. The organism’s body is only made up of cells and this level of body organisation is called Cellular level of organisation.

Pores

• The complete body has several cells which form a single structure. At places, there are several pores which allow the entry of water and dissolved molecules inside the
• They do not require a proper mouth or nose for entry of substances or anus to expel the wastes. Everything that is needed enters the body through the minute pores along with water and leaves the body through a huge single

How do sponges consume food?

• Sponges contain several pores on their surfaces named Ostia and a single large pore called Osculum.
• Ostia creates a structure like an internal canal and all the canals finally open into the larger osculum.

             

Ostia and Osculum           Choanocytes

• In the pores, there are numerous collar cells called Choanocytes. They have a flagellum, which helps to catch hold of the planktonic food that enters the ostia along with
• Food is taken in and the waste materials are sent out through the large

How do sponges reproduce?

• Sponges reproduce with the help of sexual
• The male sponge releases sperms in the water which flow with the water current and reach the female
• Internal fertilisation occurs and releases the newly formed larvae into the water. These larvae float like planktons for a few days and finally settle down at one place from where they start growing as an individual
• Sponges also prefer many ways of asexual reproduction like budding, fragmentation,
• Some species of sponges reproduce asexually by the production of specialised cells called

Gemmules.

• They are capable of surviving harsh conditions like changes in temperature, alkalinity, When the conditions are unfavourable, the gemmules are released which remain dormant and as the surrounding conditions get back to normal, they hatch into new sponges.
• Thus, sponges can reproduce both sexually and asexually and help maintain their population in adverse