Question

Filo Porifera

6. Name the parts of the external and internal anatomy of the porifers.

7. Mention the role of pinacocytes, coanocytes, amebocytes, and spicules on sponges.

8. Mention the type of nutrition that sponges exhibit.

9. Mention how gas exchange and excretion occur in sponges.

10. Explain the reproduction mechanisms exhibited by sponges.

11. Why are the sponges said to have arisen from a colonial protozoan ancestral organism?

Answer 1

6.External anatomy - Ostia,Osculum,Spicules(pinacocytes,mesohyl)

Internal Anatomy - Spongocoel,choanocytes or collar cells,Amoebocytes Cells

The outer most layer of sponge are pinacocytes are epthelial cell like,enclose a jelly-like substance called mesohyl.In some sponges,porocytes form ostia,single tube-shaped cells that act as valves to regulate the flow of water into the spongocoel.Many sponges have internal skeletons of spongin or spicule of calcium carbonate.They have internal cavity called spongocoel.The water current system is found in sponge.The choanocytes or collar cells,which are flagellated cells that generate water currents and capture food and osculum,opening through which water is expelled out.

7.Amoebocytes Cells - these cells have many types.

1. Archaeocytes - They are undifferentiated embryonic amoebocytes cells,they play a role of digestion,eliminating waste material and can give rise to both sperms and ova.

2.Collenocytes - connective tissue cells.

3.Chromocytes - Pigmented amoebocytes with lobose pseudopodia.

4.Thesocytes - Storage cells with lobose pseudopodia.

5.Myocytes - Contractile cells found around the osculum,apopyles and other pores.

6.Gland cells - attached to the body surface.

The outer most layer of sponge are pinacocytes are epthelial cell like,enclose a jelly-like substance called mesohyl.The choanocytes or collar cells,which are flagellated cells that generate water currents and capture food. Many sponges have internal skeletons of spongin or spicule of calcium carbonate.

8.Holozoic Nutrition,kind of heterotrophic nutrition which involves the ingestion of solid or liquid food and extracellular digestion occurs outside the cells and nutrition occur intracellular.

9. Sponges do not have lungs or respiratory system.They have pores,known as ostia,across their surfaces.They filter O2 from water canal system and have moist surface.

10.They have sexually and asexually reproduction.After fertilization in the sponge,a larva(gemule) is released into the water and asexul reproduction through budding.

11.Sponges said to have arisen from a colonial protozoan Because choanocytes cells of sponges resemble the choanoflagellate protozoans.