Animal Kingdom - Notes | Class 11 | Part 2: Porifera

Phylum Porifera (Sponges): General Characters

4. Animal Kingdom

Phylum Porifera (Sponges): General Characters

  • Grades of Organization: Cellular grade.
  • Symmetry: Asymmetrical. Some are radial.
  • Coelom: Acoelomate
  • Habit and Habitat: Aquatic (mostly marine). Sedentary. Solitary/colonial.
  • Digestive System: Absent. Intracellular digestion.
  • Respiratory System: Absent
  • Circulatory System: Absent
  • Reproduction:
    • Asexual (fragmentation) & Sexual.
    • Hermaphrodite (Monoecious): Male and female sex organs are seen in same individual.
    • Internal fertilization.
    • Development is indirect.
  • Unique Features:
    • Water canal (water transport) system. Millions of ostia (pores).
    • Water canal system: Here, water enters through minute pores (ostia) in the body wall into a central cavity (spongocoel), from where it goes out through osculum. Canal system is used for food gathering, gas exchange and removal of wastes.
    • Spongocoel & canals are lined with choanocytes (collar cells).
    • Body is supported by spicules and spongin fibres.
  • Examples:
    • Sycon (Scypha)
    • Spongilla (fresh water sponge)
    • Euspongia (Bath sponge)
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