1.  Thesocytes

2.  Amoebocytes

3.  Scleroblasts

1.  cell division

2.  division of labour

4.  sponge lacks blood

1.  cold shallow water

2.  warm shallow water

3.  deep sea water

1.  calcareous spicules

3.  collagen fibers

4.  yellow fibers of elastic cartilage

1.  Sea water

2.  Brackish water

4.  Sandy shore

1.  porocyte

2.  choanocyte

4.  pinacocyte

2.  silicoblasts

3.  spiroblasts

4.  spongoblasts

1.  pinacocytes

2.  choanocytes

4.  None of the above.

1.  acanthostyle

3.  diastyle

4.  style

2.  thesocytes

3.  myocytes

4.  choanocytes