1. Phylum: Porifera
The Sponges
Fig. 12.CO

2. Many are bright shades of red, orange, yellow, and green.
What is a sponge?
Sponges are asymmetrical aquatic animals that have a variety of colors, shapes, and sizes.
Many are bright shades of red, orange, yellow, and green.

3. Section 26.1 Summary – pages 693-697
What is a sponge?
Although sponges do not resemble more familiar animals, they carry on the same life processes as all animals.
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4. Section 26.1 Summary – pages 693-697
Sponges are pore-bearers
Sponges are classified in the invertebrate phylum Porifera, which means “pore bearer.”
Most live in marine biomes, but about 150 species can be found in freshwater environments.
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5. B. Form and Function
1. Body openings consist of small incurrent pores or ostia and a few excurrent oscula.
2. Openings are connected by a system of canals; water passes from ostia to osculum.
3. Choanocytes or flagellated collar cells line some of the canals.
a. They keep the current flowing by beating of flagella.
b. They trap and phagocytize food particles passing by.
4. The framework of the sponge is composed of needle-like calcareous or siliceous spicules or organic spongin fibers.

6. Section 26.1 Summary – pages 693-697
Sponges are pore-bearers
Water out
Sponges are mainly sessile organisms.
Central
cavity
Because most adult sponges can’t travel in search of food, they get their food by a process called filter feeding.
Water in
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7. Section 26.1 Summary – pages 693-697
Sponges are pore-bearers
Water out
Filter feeding is a method in which an organism feeds by filtering small particles of food from water that pass by or through some part of the organism.
Central
cavity
Water in
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Osculum
A Sponge
Pore cell
Epithelial-like
cells
Amoebocyte
Collar cells
Direction of
water flow
through pores
Spicules
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Cell organization in sponges
For some sponge species, if you took a living sponge and put it through a sieve, not only would the sponge’s cells be alive and separated out, but these cells would come together to form new sponges.
It can take several weeks for the sponge’s cells to reorganize themselves.
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Cell organization in sponges
Many biologists hypothesize that sponges evolved directly from colonial, flagellated protists, such as Volvox.
Volvox
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Cell organization in sponges
More importantly, sponges exhibit a major step in the evolution of animals—the change from unicellular life to a division of labor among groups of organized cells.
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Reproduction in sponges
Sponges can reproduce asexually and sexually.
Depending on the species, asexual reproduction can be by budding, fragmentation, or the formation of gemmules.
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Reproduction in sponges
An external growth, called a bud, can form on a sponge.
If a bud drops off, it can float away, settle, and grow into a sponge.
Sometimes, buds do not break off. When this occurs, a colony of sponges forms.
Often, fragments of a sponge break off and grow into new sponges.
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Reproduction in sponges
Some freshwater sponges produce seedlike particles, called gemmules, in the fall when waters cool.
The adult sponges die over the winter, but the gemmules survive and grow into new sponges in the spring when waters warm.
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Reproduction in sponges
Most sponges reproduce sexually.
Some sponges have separate sexes, but most sponges are hermaphrodites. A hermaphrodite (hur MAF ruh dite) is an animal that can produce both eggs and sperm.
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Reproduction in sponges
Eggs and sperm form from amoebocytes.
During reproduction, sperm released from one sponge can be carried by water currents to another sponge, where fertilization can occur.
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Reproduction in sponges
Fertilization in sponges may be either external or internal.
A few sponges have external fertilization—fertilization that occurs outside the animal’s body.
Most sponges have internal fertilization, in which eggs inside the animal’s body are fertilized by sperm carried into the sponge with water.
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Egg
cell
Sperm
cells
Flagella
Larvae
New sponge
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Reproduction in sponges
In sponges, the collar cells collect and transfer sperm to amoebocytes.
The amoebocytes then transport the sperm to ripe eggs.
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20. Support and defense systems in sponges
Sponges are soft-bodied invertebrates, that can be found at depths of about 8500 m.
Their internal structure gives them support and can help protect them from predators.

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Support and defense systems in sponges
Some sponges have sharp, hard spicules located between the cell layers.
Spicules may be made of glasslike material or of calcium carbonate.
Spicules
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Support and defense systems in sponges
Other sponges have an internal framework made of silica or of spongin, a fibrous protein-like material.
Sponges can be classified according to the shape and makeup of their spicules and/or frameworks.
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Support and defense systems in sponges
Besides sharp spicules, some sponges may have other methods of defense.
Some sponges contain chemicals that are toxic to fishes and to other predators.
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24. Summary: Phylum Porifera General Features
1. Porifera means "pore-bearing"; their sac-like bodies are perforated by many pores.
2. They are sessile and depend on water currents to bring in food and oxygen and carry away wastes.
3. Their body is a mass of cells embedded in gelatinous matrix and stiffened by spicules of calcium carbonate or silica and collagen.
4. They have no organs or tissues; cells are somewhat independent.
5. Being sessile, they have no nervous or sense organs and have simplest of contractile elements.
6. They are aside from the mainstream of animal evolution; thus they are often called Parazoa.
7. Most of the 5000 species are marine; about 150 are freshwater.
8. Morphology changes with substratum, calmness of water, etc.
9. Sponges are ancient; fossils extend to Cambrian or earlier.

25. 5. There are three types of canal systems.
a. Asconoids: Flagellated Spongocoels
1) Asconoids are simplest; they are small and tube- shaped.
2) Water enters a large cavity, the spongocoel, lined with choanocytes.
3) Choanocyte flagella pull water through.
4) Asconoids can be in the Class Calcerea: Leucosolenia and Clathrina are examples.

26. b. Syconoids: Flagellated Canals
1) They resemble asconoids but are bigger with a thicker body wall.
2) The wall contains choanocyte- lined radial canals that empty into the spongocoel. (Fig.12-7)
3) Water entering filters through tiny openings called prosopyles.
4) The spongocoel is lined with epithelial cells rather than choanocytes.
5) Food is digested by choanocytes.
6) Flagella force the water through internal pores called apopyles into the spongocoel and out the osculum.
7) They pass through an asconoid stage in development but do not form highly branched colonies.
8) The flagellated canals form by evagination of the body wall; this is developmental evidence of being derived from asconoid ancestors.
9) Classes Hexactinellida have species that are syconoid; the genus Sycon is an example.

27. c. Leuconoids: Flagellated Chambers
1) These are most complex and are larger with many oscula. (Fig )
2) Clusters of flagellated chambers are filled from incurrent canals, discharge to excurrent canals.
3) Most sponges are leuconoid; it is seen in most Calcarea and in all other classes.
4) The leuconoid system has evolved independently many times in sponges.
5) This system increases flagellated surfaces compared to volume; more collar cells can meet food demands. Its all about surface-to- volume ratios and energy extraction!!!

28. 7. Sponge Physiology
a. Filtration Rates
1) Leuconia, a small sponge, has 81,000 incurrent canals.
2) It would have more than two million flagellated chambers.
3) Expulsion of water carries wastes some distance away.
4) Some large sponges can filter 1500 liters of water a day.
b. Particles are filtered nonselectively; choanocytes phagocytize 80%.
c. Digestion is completely intracellular, primarily by archaeocytes.
d. There are no excretory or respiratory organs; diffusion suffices.
e. The only movements are very slow opening and closing of pores; nerve cells have not been demonstrated.

29. D. Class Calcarea (Calcispongiae)
1. These are calcareous sponges with spicules of calcium carbonate.
2. The spicules are straight or have three or four rays.
3. Most are small sponges with tubular or vase shapes.
4. Asconoid, syconoid and leuconoid forms all occur.
E. Class Hexactinellida (Hyalospongiae)
1. These are glass sponges with six-rayed spicules of silica.
2. Nearly all are deep-sea forms; most are radially symmetrical.
F. Class Demospongiae
1. This class contains 95% of living sponge species.
2. Spicules are siliceous but not six rayed; they may be absent or bound together by spongin.
3. All are leuconoid and all are marine except for Spongillidae, the freshwater sponges.

30. Sponge Cell Types and Functions (Objective 3)
-Choanocyte (collar cells): flagellated collar cells which keep the current flowing by beating flagella. They trap and phagocytize food particles passing by. They also can produce sperm
-Archaeocytes: Cells which digest particles to provide nutrients.
-Amoebocytes: amoeba-like cells found throughout the sponge; store, digest and transport food, excrete wastes, secrete skeleton and also may give rise to buds in asexual reproduction.
-Epithelial-like cells: These cells are thing and flat. They contract in response to touch or to irritating chemicals. In so doing, they close pores in the sponge.
-Pore Cell: Surrounding each pore is a pore cell. Pore cells allow water carrying food and oxygen into the sponge’s body.