Question

Identify the characteristics of porifera​

Answer 1

1. Porifera are all aquatic, mostly marine except one family Spongillidae which lives in freshwater.
2. They are sessile and sedentary and grow like plants.
3. The body shape is vase or cylinder-like, asymmetrical or radially symmetrical.
4. The body surface is perforated by numerous pores, the Ostia through which water enters the body and one or more large openings, the oscula by which the water exists.
5. The multicellular organism with the cellular level of body organization. No distinct tissues or organs.
6. They consist of outer ectoderm and inner endoderm with an intermediate layer of mesenchyme, therefore, diploblastic
7. The interior space of the body is either hollow or permeated by numerous canals lined with choanocytes. The interior space of the sponge body is called spongocoel.
8. Characteristic skeleton consisting of either fine flexible spongin fibers, siliceous spicules or calcareous spicules.
9. Mouth absent, digestion intracellular.
10. Excretory and respiratory organs are absent.
11. Contractile vacuoles are present in some freshwater forms.
12. The nervous and sensory cells are probably not differentiated.
13. The primitive nervous system of neuron arranged in a definite network of bipolar or multipolar cells in some, but is of doubtful status.
14. The sponges are monoecious.
15. Reproduction occurs by both sexual and asexual methods.
16. Asexual reproduction occurs by buds and gemmules.
17. The sponge possesses a high power of regeneration.
18. Sexual reproduction occurs via ova and sperms.
19. All sponges are hermaphrodite.
20. Fertilization is internal but cross-fertilization can occur.
21. Cleavage holoblastic.
22. Development is indirect through a free-swimming ciliated larva called amphiblastula or parenchymula.
23. The organization of sponges are grouped into three types which are ascon type, sycon type, and leuconoid type, due to simple and complex forms.
24. Examples: Clathrina, Sycon, Grantia, Euplectella, Hyalonema, Oscarella, Plakina, Thenea, Cliona, Halichondria, Cladorhiza, Spongilla, Euspondia, etc.

Answer 2

Answer :

Porifera :-

1. These are the organisms with holes.

2. There are pores all over the body.

3. These animals are covered with a hard outside layer of skeleton.

4. They are commonly called sponges.

5. Found in marine habitats.

6. They are asymmetrical in shape.

7. The digestion is intracellular.

8. Ex : Sycon, Spongilla.