1. Unit Phylum Porifera

2. Phylum Porifera Multicellular Body with pores (ostia)
No organs or true tissues.
No nervous system
Adults sessile & attached to substratum.
Skeleton of calcareous spicules, siliceous spicules, spongin made of collagen or a combination.
No respiratory, circulatory, or nervous systems
All aquatic, mostly marine.

3. Phylum Porifera Composed of 3 layers
outer layer of flattened contractile cells (pinacocytes)
inner non-living mesenchyme containing a variety of specialized cells
collar cells (choanocytes) which capture food, etc. from water flowing through channels.
Exhibit asymmetry or radial symmetry.

4. Simple Sponge Morphology
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Simple Sponge Morphology

6. Spicules
Skeleton of sponge
Calcium carbonate
Silicon
Collagen

7. Sclerocytes
Produce spicules

8. Mesenchyme (Mesoglea)
Gelatinous matrix that holds all the living cells of a sponge in place

9. Pinacocytes Comprise the outer surface of a sponge
Contractile – can regulate the amount of water that is able to enter the sponge

10. Porocytes
Forms the walls of the pores (ostia) through which water is able to enter the sponge

11. Choanocytes Flagellated cells
Rear end anchored in the mesenchyme, collar and flagellum exposed to the inner sponge cavity
Flagellum creates water currents
Collar traps food
Passes food to archeocyte

12. Archeocytes Amoeboid cells Receive food from choanocytes
Able to move throughout the mesenchyme to deliver food to all other cells in the sponge
Able to differentiate into other cell types

13. Fig. 12.5
Three Sponge Body Types
Fig. 12.5

14. Asconoid Sponges
Asconoid sponges have a stalk-like shape and a large, central atrium
Choanocytes are only located along the inner walls of the atrium
Asconoid sponges are often small, many no larger than 1mm in diameter, due to limits on nutritional uptake caused by simple choanocyte orientation

15. Syconoid Sponges
Syconoid sponges possess folded walls that increase the surface area of the animal
Water passes through radial canals located in these folds which also contain much higher numbers of choanocytes than is seen in asconoid sponges
No choanocytes are anchored to the inner walls of the atrium
May grow up to several centimeters in diameter

16. Fig. 12.7
Fig. 12.7

17. Leuconoid Sponges The most common type of sponge body plan
Inner atrium is almost non-existent
Inner sponge is filled almost entirely with mesenchyme crisscrossed by by a network of chambers that all contain large numbers of choanocytes
Largest surface area to volume ratio of any sponge allows leuconoid sponges to grow to over a meter in diameter

18. Three Sponge Body Types
Asconoid
Syconoid
Leuconoid

19. Class Calcarea Small – 4 inches or less Vase shaped
Found in shallow waters around the world
Asconoid, Syconoid, or Leuconoid
Spicules of calcium carbonate
Straight or 3-4 rays

20. Class Hexactinellida Vase-like Delicate Glass sponges
Found in deep, tropical waters
Leuconoid only
Spicules
Siliceous
6 rays

21. Class Hexactinellida Euplectella

22. Class Demospongiae Largest number of sponges are in this class
Bath sponges
Found in shallow, warm waters to abyssal waters 5 miles deep
Only type of sponge possible to find in fresh water
Leuconoid
Spicules
Siliceous (rounded)
Spongin (cellulose)

23. Fig a

25. Sexual Reproduction Monoecious Sperm and egg derived from choanocytes
Both male and female gametes produced by a single sponge
Sperm and egg derived from choanocytes
Reproduce en-masse during certain times of the year when the moon and water temperature are at a specific point
Once fertilized, the larvae grow cilia and swim to a new location to grow

26. Asexual Reproduction
Sponges are able to reproduce asexually by two different methods
Fragmentation
Similar to cloning plants
A small portion may be severed from the rest of the body and it will grow as a new sponge on its own
Gemmule formation
When conditions become harmful to a sponge, it can produce a type of seed that may lie dormant for years until conditions become more favorable

27. Precambrian Before 670 MYA Porifera Platyhelmithes Mollusca Arthropoda
Echinodermata
Hemichordata
Cnidaria
Nemertea
Annelida
Lophophores
Chordata
Precambrian
Before 670 MYA
Protozoans

28. Hypothesis of Multicellularity
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Hypothesis of Multicellularity

29. The End
CO 12
Fig. 12.CO