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)
Select Topic 👇
- Topic 1: Basis of Classification
- Topic 2: Porifera
- Topic 3: Cnidaria
- Topic 4: Ctenophora
- Topic 5: Platyhelminthes
- Topic 6: Aschelminthes
- Topic 7: Annelida
- Topic 8: Arthropoda
- Topic 9: Mollusca
- Topic 10: Echinodermata
- Topic 11: Hemichordata
- Topic 12: Chordata - up to Sub phylum Vertebrata
- Topic 13: Chordata - Cyclostomata, Pisces
- Topic 14: Chordata - Tetrapoda