phylum porifera...zoology ..topic..science learning..presentation

1. Phylum Porifera
The Sponges

2. • Commonly known as sponges.
• ~ 9,000 species
• They are pore-bearing multi-cellular animals.
• lack germ layer.
• No internal organs.
• No muscles.
• Sessile, fixed, immobile.
• Asymmetric.

3. Three types of cells involved in sponge
formation
1. Pinacocytes.
2. Choanocytes.
3. Mesenchyme.
1. Pinacocytes:
• Will form pinacoderm.
• Some specialized as porocytes, and regulate
water circulation.

5. 2. Choanocytes:
• Will form inner layer choanoderm.
• They are flagellated collar cells.
• Flagellum and collar together, are used to gather
food.

6. Nucleus

7. 3. Mesenchyme cells:
• These cells specialized to perform function
in:
1. Reporoduction.
2. Transport.
3. Storing food.

8. Sponge Structure
• Simple in structure.
• One end attach to solid substratum.
• Other end has opening, Osculum.
• Ostia present over the body surface.
• Outer layer is pinacoderm.
• Inner layer is choanoderm.
• Between them is mesohyl.
• Large internal cavity is spongocoel.

9. Sponges have skeleton.
Two main component of skeleton:
1. Spongin: a proteinecious fibrous network.
2. Spicules: Needle-like spikes of silicon or
cacium carbonate.
• Provide support to sponge

11. Water Canal System
Essential element of water current system are:
1. Choanocytes/collar cells:
• Generate water current.
• Capture food particals and carry oxygen.
2. Osculum:
• An opening through which water is expelled.

12. Three types of sponge body form are described
based on the arrangement of water-current
system:
1. Ascon.
2. Sycon.
3. Leucon.

13. Ascon
Ascon sponges have very simple canal system.
• Vase-like shape.
• Water enter through ostia
• Lead to large internal cavity spongocoel.
• Expelled through osculum.

14. Sycon
• Osculum and spongocoel present.
• Body wall invaginations are incurrent canal.
• Incurrent canals have dermal pores.
• Pores connect incurrent canal to radial canal.
• Water enter through pores of incurrent and radial
canal into the spongocoel and expelled through
osculum.

15. Leucon
• Complex water current system.
• Have extensively branched canal system.
• Incurrent canal branching will form
choanocytes chamber.
• Canal carrying water away from chambers are
excurrent canals.
• Spongocoel absent.
• Multiple osculum.

18. • Sponges consume bacteria or small prey.
• Choanosytes sweep and filter suspended food
particles.
• Digestion begins in food vacuole.
• Partially digested food pass to mesohyl for
distribution.
• Pinacocytes phagocytize large food particle.
• Gas exchange and nitrogenous waste remove
by diffusion.
Feeding

20. Reproduction
Reproduce by sexual and asexual manner.
Sexual Reproduction:
• Hermaphrodite animals.
• Protogynous/Protandrous
• Avoid self-fertilization.
• Choanocytes will form sperms and eggs.
• Sperm released through osculum.

21. • Sperm from one sponge enter the body of
another sperm and trapped by choanocytes.
• After fertilization zygote will form.
• Early development lead to formation of
flagellated larva.
• Larva moves out from parent sponge.
• Attach to substratum and develop into new
adult.

23. Asexual Reproduction:
• Sponges reproduced asexually by
gemmulation.
• Mesenchyme cells enclosed themselves in
protective capsule to overcome adverse
condition.
• Capsule expelled from parent sponge.
• Under favorable conditions, cells comes out
from capsule by micropyle.
• Organize themselves into new sponge.

25. Classification
1. Class Calcarea:
• Calcareous sponges.
• Spicules made of calcium
carbonate.
• They are tubular.
• Body form may be ascon,
sycon or leucon.

26. 2. Class Hexactinellida:
• Commonly known as glass sponges.
• Spicules bound in glass-like lattice.
• They are siliceous.
• Body form may be sycon or leucon.
3. Class Demospongia:
• They have spicules and spongin.
• Spicules are siliceous.
• Body form is leucon.

27. Glass Sponge

28. Demosponge