Porifera:
A group of metazoan animals whose bodies are without any symmetry or radially symmetrical without mouth and nervous system and whose bodies are provided with many pores, canals, and choanocyte cells through which water flows are recognized as Porifera or Sponges.
General Characteristics of Porifera:
1. All sponges are aquatic, marine, or freshwater, remain attached to some submerged substratum and grow like plants.
2. Except spongilla group all are marine.
3. Body flower-vase-like or tubular with radial symmetry or without any symmetry.
4. Multicellular body provided with many pores known as Ostia through which water flows inside and water is expelled through one or two large openings known as Osculum.
5. The space in between ectoderm and endoderm is filled with mesenchyme so the animal is diploblastic. They show a cellular grade of construction without organs or systems.
6. Body is traversed internally by many canals known as ascon, sycon, and leucon types of the canal system.
7. Flagellated cells or choanocytes line the radial canal.
8. Internal skeleton is made up of spongin fiber, and siliceous or calcareous spicules.
9. No mouth, no nervous system, no sensory cells.
10. Reproduction sexual or asexual, asexual reproduction takes place by the formation of gemmules.