Animal Classification

CHAPTER NO-5

KINGDOM ANIMALIA

Phylum Porifera
(GK: Porous = Pores + Ferro = form)

Main characters:
1. They are commonly called as sponges.
2. They are sessile animals.
3. Sponges range in height from about 1cm to 2cm.
4. More than 5000 species of sponges are found.
5. All are marine, while some are fresh water.
6. The central body cavity is called spongocoel.
7. A single large opening is called as osculum.
8. They are filter feeders.
9. Body lining is formed by flagellated cells called choanocytes or collar cells.
10. They are diploblastic and porous, pores called ostia.
11. They layers of body are separated by a gelatinous region called the mesophyl.
12. Gametes arise from ameobocytes.
13. Pores are made up of porocytes.
14. Internal skeleton is made up of spicules.
15. These spiculles are made up of silicon, calcium carbonate or a protein called sponging.
16. Most sponges are hermaphrodites.
17. Cross-fertilization is found.
18. Asexual reproduction occurs by fragmentation and gemmule formation.
19. Fertilization occurs in the mesohyl.
20. Regeneration is also found.
21. Sponges have no nerves or muscles.
Examples: Sycon, Leucosolenia, Spongilla.

Classes of phylum porifera
Following are the main classes of Phylum Porifera:
1. Class : Calcaria
2. Class : Hexactinellida
3. Class : Demospongia 1. Class: Calcaria
Main characters:
1. They are simple sponges.
2. The spicules are calcareous.
3. They are marine and fresh water.
4. They are non-motile.
5. Body is elongated.
Example: Sycon, Leucosolenia

2. Class: Hexactinellida

Main Characters:
1. These are glass sponges.
2. The spicules are siliceous.
3. These spicules are united in net or separate form.
4. They are elongated shaped.
Example: Euplectella (Venus’s Flower-basket)

3. Class: Demospongia

Main Characters:
1. They are