1. Phylum Porifera: Sponges
Chapter 6

2. The Sponges Phylum Porifera (Latin porous, “pore”; ferre : “to bear”).
About 5,500 living species most marine although there are about 200 freshwater species.

4. Characteristics of Sponges
Metazoa: without true tissue. Cellular grade of complexity (Parazoa).
Adults asymmetrical or superficially radially symmetrical.
Unique flagellated cells the choanocytes that drive water through canals and chambers: the aquiferous system.
Adults sessile suspension feeders; larval stages are motile.
Reproduction sexual or asexual.

6. The Poriferan Bauplan Two unique organizational attributes:
The aquiferous system
Highly totipotent nature of sponge cells

7. Overview of general structures
Sponges move water through their bodies using choanocytes
All cells are loosely arranged into a gelatinous matrix, the mesohyle
Water enters small holes called ostia
Water exits large holes called oscula
A skeleton helps maintain the structure of the sponge.

8. Body Structure and the Aquiferous System
The mesohyl includes a non cellular coloidal mesoglea in which are embedded collagen fibers, spicules and various cells.
Most of these cells are able to change from one type to another as required.
Water flows through the ostia all the chanels and eventually out through the osculum.
Dermal pores or ostia 3)

9. Types of Canal Systems
Most sponges can be separated based on their type of canal system.
1. Asconoid
2. Syconoid
3. Leuconoid

10. Asconoid sponges
Found in radially symmetrical calcarous sponges: rarely exceed 10cm in height.

11. Asconoid sponges Simple organization
Water moves through the ostia into the spongocoel
Choanoderm simple and continuous one cell thick.

12. Fig. 6.3 Asconoid condition Choanoderm simple and
continuous one cell thick.

13. Fig. 6.3 3 Asconoid water flow 2 1 Water flow: 1) ostium 
2) choanoderm  3) osculum 2 1

14. #1 #2 #3

15. Syconoid sponges
Syconoid condition: simple folding of the pinacoderm and choanoderm.
As complexity increases the mesohyl may thicken and appear to have two layers.
Water is brought in through the incurrent canals and then to radial canals (lined with choanocytes).

16. Fig. 6.3 Syconoid condition
Choanoderm restricted to chambers with an apopyle opening into the atrium.

17. Fig. 6.3 Syconoid water flow Water flow: 1) incurent pore
 2) incurrent canal 
3) prosopyle  4) choanocyte
chamber  5) apopyle 
6) atrium  6) osculum

18. Leuconoid sponges
Additional folding of the choanoder and further thickening of the mesohyl.
Water is brought in through incurrent canals, and discharged through excurrent canals.
Most common type.

19. Fig. 6.3 Leuconoid condition
The atrium is reduced to a series of excurrent canals.
Water flow: 1) dermal pore
 2) incurrent canal 
3) prosopyle  4) choanocyte
chamber  5) apopyle 
6) excurent canal 
7) osculum

21. The more complex a sponge condition the more particles it can filter from the water column.

22. Types of Cells Pinacocytes (Epidermal Cell)
Porocytes (Water Flow Through Cell)
Choanocytes (Collar Cells)
Archeocytes (Amoebocytes)

23. I. Pinacocytes Cells of the external epithelium Main functions:
Structure
Contraction

24. II. Porocytes
Cells which form pores
Function: to allow water flow

25. III. Chanocytes Line the flagellated canals and chambers.
Main function: to create water flow.

26. Codosiga

28. Sponge feeding

33. Diameter of channels influences water flow velocity.
Particles that are captured are in the 2-5 µm range.

34. Cladorhizid carnivorous sponge
Predatory sponges
Cladorhizid carnivorous sponge

35. The Harp Sponge, Chondrocladia lyra

36. IV. Archaeocytes Amoeboid cells which can be non-sessile
Found in cellular matrix
Main function:
Digestion
Secrete structural components
Spongin
Spicules

37. Sponge feeding

38. Sclerocyte in the process of secreting a spicule

39. Keeping the mesohyle together
Spongin
Spines (spicules)
Siliceous
Calcareous

40. Spongin
Fibers of collagen

41. Spicules
Spines, when placed together form a very rigid skeleton

42. Megascleres And Microscleres

43. Main Groups of Sponges P: Porifera C: Calcarea C: Hexactinellida
C: Desmospongiae

44. Calcarea Calcareous sponges Spicules composed of calcium carbonate
Small < 10 cm tall

45. Calcareous sponges

46. Hexactinellida Glass sponges Some spicules fused to form skeleton
Spicules made of glass (Siliceous spicules) six rayed
Deep water sponges

47. Siliceous spicules in Hexactinellida (Triaxon) six rayed spicules.

49. Desmospongiae Common sponges Skeleton is variable Can be large
Spicules
Spongin
both
Can be large

50. Siliceous Spiculse in Desmospongia
Never six-rayed
Microscleres
Megascleres

51. Sclerospongiae
Sclerosponges were first proposed as a class of sponges, in 1970 by Hartman and Goreau.
Sclerosponges are sponges with a soft body that covers a hard, often massive limestone basal skeleton.
Because of their long life span (500-1,000 years) it is thought that analysis of these sponges could extend data regarding ocean temperatures, salinity, and other variables farther into the past than has been previously possible.
However, it was later found that the sclerosponges are not a monophyletic group (they are polyphyletic) and therefore this class is currently not recognized.

52. The Big Picture Sponges are metazoans, but don’t have true tissues
They are an ancient group
Three main groups (taxonomic), which fall into three main structural groups
Four types of specialized cells *choanocyte*