1. Porifera Notes

2. General Characteristics
Phylum Porifera means “pore-bearing”. Their sac-like bodies are perforated by many pores
As adults, all sponges are sessile although in their larval form they are motile. When sessile, they depend on water currents to bring them food and oxygen and remove waste products

3. General Characteristics
C. The sponge body is an efficient water filter. Some large sponges can filter 1500 liters each day

4. General Characteristics
D. There are approximately 8300 species of sponge Most of these are marine a few live in brackish water and 150 species are freshwater

5. General Characteristics
They have radial symmetry

6. General Characteristics
Sponges are considered to be multi-cellular but they have no tissues or organs; each cell of their body functions somewhat independently
They have no sense organs or nervous system

7. General Characteristics
H. Porifera have few predators. They have a foul taste and noxious odor and also have a defensive skeleton system

8. General Characteristics
The Porifera phylum is very ancient with fossil records stretching back to the Cambrian epoch mya.

9. General Characteristics
The skeletal structure of a sponge can be either fibrous or rigid or both.
1. the fibrous part is made up of a specialized collagen material called spongin

10. General Characteristics
2. the rigid component of the sponge skeleton is made up of calcium carbonate (CaCO3) or silica (glass) spicules.

11. General Characteristics
2. (con’t) These spicules may be needle like, star shaped or six-rayed and embedded in the spongin or the inter cellular matrix called the mesohyl (gelatinous layer)
Siliceous Spicules

12. General Characteristics
Living sponges are assigned to one of four classes
Calcarea

13. General Characteristics
Living sponges are assigned to one of four classes
Hexactinellida

14. General Characteristics
Living sponges are assigned to one of four classes
Demospongiae

15. General Characteristics
Living sponges are assigned to one of four classes
Homoscleromorpha

16. General Characteristics
1. Taxonomists use the type of spicule as a classification tool a. Members of Class Calcarea have CaCO3 spicules with 2, 3, or 4 rays

17. General Characteristics
b. Class Hexactinellida sponges have 6-rayed siliceous spicules

18. General Characteristics
c. Class Demospongiae have glass spicules but not six-rayed, spongin only or both spicules and spongin depending on the species

19. General Characteristics
d. Class Sclerospongiae have massive CaCO3 (calcareous) skeletons and siliceous spicules

20. Form & Function There are two types of body opening in sponges
Small incurrent pores are called ostia (ostium)
Large excurrent pores are called oscula
(osculum)

21. Form & Function
B. Inside the sponge body, water is directed past choanocyte cells where food & oxygen (O2) are collected. Choanocyte cells a.k.a. collar cells and have 2 main purposes

22. Form & Function
Choanocyte cells a.k.a. collar cells and have 2 main purposes – 1. they keep water flowing through the sponge by beating their flagella 2. they trap food particles passing by. (See pg 245 – figure 12-7 in text)

23. Form & Function
Sponges non-selectively phagocytize food particles between the sizes of .1 um and 50 um
(with the majority being the smaller sizes)
(um = micrometer)
(see page 247 – figure in text)

24. Types of Canal Systems
Asconoid canal system is a flagellated spongocoel
Simplest for of canal system, sponges with this type of canal are small and tube-shaped

25. Types of Canal Systems
Water flows through a large central space called the spongocoel (sponge body cavity) and it is lined with choanocyte cells. Flagella pull water through but much water flows through unfiltered
The only class of sponges that have asconoid canal systems are some of the calcerea

26. Types of Canal Systems Syconoid canal systems – flagellated canals
Sponges with this canal system are larger and thicker walled than the asconoids

27. Types of Canal Systems
The body walls hold radial canals that are lined with the choanocyte cells so that water is filtered before it empties into the spongocoel
Syconoid canal systems are found in Calcarea and
Hexatinellida classes

28. Types of Canal Systems Leuconoid canal systems – flagellated chambers
These are the most complex types of sponges
Because they are more efficient at extracting food particles from water they can grow much larger. They have many oscula (excurrent canals)

29. Types of Canal Systems
c. Clusters of flagellated chambers are filled with choanocyte cells and they are filled from incurrent canals and discharge into excurrent canals

30. Types of Canal Systems Largest of all sponges have this canal system
It is found in all three classes
1. Calcarea
2. Demospongiae
3. Hexactinellida

31. D. Types of Sponge Cells
1. Sponge cells are arranged in a gelatinous matrix called mesohyl ; this is the connective tissue of sponges

32. D. Types of Sponge Cells
Because of the absence of true tissues, all fundamental processes must occur at the cellular level
The only visible movement in sponges is the closing and opening of the pores

33. D. Types of Sponge Cells
Choanocytes are also called flagellated collar cells
One end is embedded in the mesohyl; this is called the cell body
The exposed end has a mucous collar to collect food
A flagella which waves to trap food particles and create water currents

34. D. Types of Sponge Cells Archaeocytes are also called amoebocytes
They can move about in the mesohyl by psuedopods
They phagocytize food particles
They can repair wounds because they can differentiate into any type of cell needed by the sponge

35. D. Types of Sponge Cells
They can become schlerocytes to secrete spicules
They can become spongocytes to secrete spongin
They can become pinacocytes to repair the pinacoderm
They can become collencytes to secrete collagen

36. D. Types of Sponge Cells Pinacocytes – flat epithelial cells
a. Form the outer dermis of the sponge called the pinacoderm

37. E. Regeneration
Sponges have great ability to regenerate lost parts and repair injuries
Sponge fragments have the ability to re-aggregate into new structures-this is called somatic embryogenesis; this process is largely due to the ability of the archaeocytes to differentiate into any type of sponge cell

38. F. Reproduction Asexual reproduction
Includes regeneration following fragmentation
Internal buds called gemmules to survive drought & freezing

39. F. Reproduction
C. External buds are small sponges that break off the adult after attaining a certain size (called budding)

40. F. Reproduction Sexual Reproduction (for most sponges)
Most sponges are monoecious with both male and female sex cells in one individual
Sperm are formed from transformed choanocytes and when mature they will release from the mesohyl and swim away using their flagella

41. F. Reproduction continued
c. When sperm are released from one sponge they may be inhaled into the incurrent ostia of an adjacent sponge
When a choanocyte’s flagella traps the sperm instead of digesting it, the choanocyte becomes fertilized and turned into a zygote
The archaeocytes provide nourishment until the zygote develops into a ciliated larvae and swims away out through the oscula
3. Some sponges release both oocytes (eggs) and sperm out into the water and practice external fertilization

42. Classes of Sponges Class Calcarea
Calcareous sponges with spicules of CaCO3
Spicules have straight or 3-4 rays
Most are small and tube or vase shaped
Some are bright red, yellow or purple
Found in shallow marine water habitats to 50 meters
Asconoid, Syconoid and Leuconoid canal forms

43. B. Class Hexactinellida
Glass sponges with 6-rayed spicules made of silica
Deep sea forms to 500 meters
Root spicules attach them to the substrate
Their spicules form a latticework of fantastic shapes
Their fragile glass skeletons only allow them to live in the areas of calm and gently flowing water
Body design shows both syconoid and leuconoid canal forms

44. C. Class Demospongiae
This class contains 95% of all living sponge species
This is the only class that has species without spicules at all. Some of the species only have skeletons made of spongin
If they do have spicules, they are of silica but are not 6-rayed
This is the only class with freshwater species the Spongillia freshwater sponges flourish in warm summer waters but die back in winter and leave gemmules, usually found in well-oxygenated ponds and streams
Commercial bath sponges are harvested from this class
All species of this class are leuconoid canal design