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End Show Slide 1 of 35 Copyright Pearson Prentice Hall Biology.

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1 End Show Slide 1 of 35 Copyright Pearson Prentice Hall Biology

2 End Show Slide 2 of 35 Copyright Pearson Prentice Hall 26-2 Sponges

3 End Show 26-2 Sponges Slide 3 of 35 Copyright Pearson Prentice Hall What is a Sponge? Sponges are in the phylum Porifera which means “pore-bearers.” Sponges live their entire adult life attached to a single spot.

4 End Show 26-2 Sponges Slide 4 of 35 Copyright Pearson Prentice Hall What is a Sponge? Why are sponges classified as animals?

5 End Show 26-2 Sponges Slide 5 of 35 Copyright Pearson Prentice Hall What is a Sponge? Sponges are classified as animals because they are : multicellular heterotrophic have no cell walls contain a few specialized cells

6 End Show 26-2 Sponges Slide 6 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges How do sponges carry out essential functions?

7 End Show 26-2 Sponges Slide 7 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Sponges do not have a mouth or gut, and they have no tissues or organ systems.

8 End Show 26-2 Sponges Slide 8 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Body Plan Sponges are asymmetrical; they have no front or back ends, no left or right sides.

9 End Show 26-2 Sponges Slide 9 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges The body of a sponge forms a wall around a large central cavity through which water is circulated continually. Central cavity

10 End Show 26-2 Sponges Slide 10 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Water enters through pores located in the body wall and leaves through the osculum, a large hole at the top of the sponge. Water flow Osculum Pores

11 End Show 26-2 Sponges Slide 11 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Choanocytes are specialized cells that use flagella to move a steady current of water through the sponge. Pore Choanocyte

12 End Show 26-2 Sponges Slide 12 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges The movement of water through the sponge provides a simple mechanism for feeding, respiration, circulation, and excretion.

13 End Show 26-2 Sponges Slide 13 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Sponges have a simple skeleton. In harder sponges, the skeleton is made of spiny spicules. A spicule is a spike- shaped structure made of calcium carbonate or silica. Spicule

14 End Show 26-2 Sponges Slide 14 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Spicules are made by archaeocytes, which are specialized cells that move around within the walls of the sponge. Archaeocytes

15 End Show 26-2 Sponges Slide 15 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Feeding Sponges are filter feeders. As water moves through the sponge, food particles are trapped and engulfed by choanocytes that line the body cavity.

16 End Show 26-2 Sponges Slide 16 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges These particles are then digested or passed on to archaeocytes, who complete the digestive process and transport digested food throughout the sponge.

17 End Show 26-2 Sponges Slide 17 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Respiration, Circulation, and Excretion Sponges rely on movement of water through their bodies to carry out body functions. Oxygen dissolved in the water diffuses into the surrounding cells. Carbon dioxide and other wastes, such as ammonia, diffuse into the water and are carried away.

18 End Show 26-2 Sponges Slide 18 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Response Sponges do not have nervous systems that would allow them to respond to changes in their environment. However, many sponges protect themselves by producing toxins that make them unpalatable or poisonous to potential predators.

19 End Show 26-2 Sponges Slide 19 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Reproduction Sponges can reproduce sexually or asexually. In most sponge species, a single sponge forms both eggs and sperm by meiosis. The eggs are fertilized inside the sponge’s body, in a process called internal fertilization.

20 End Show 26-2 Sponges Slide 20 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Sperm are released from one sponge and are carried by water currents until they enter the pores of another sponge.

21 End Show 26-2 Sponges Slide 21 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Archaeocytes carry the sperm to an egg.

22 End Show 26-2 Sponges Slide 22 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges After fertilization, the zygote develops into a larva. A larva is an immature stage of an organism that looks different from the adult form.

23 End Show 26-2 Sponges Slide 23 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges The larvae of sponges are motile. Water currents carry the larva until it attaches to a surface and grows into a new sponge. New sponge Swimming larva Mature sponge (2N)

24 End Show 26-2 Sponges Slide 24 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Sponges can reproduce asexually by budding or by producing gemmules. In budding, part of a sponge breaks off of the parent sponge, settles to the sea floor, and grows into a new sponge.

25 End Show 26-2 Sponges Slide 25 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges In difficult environmental conditions, some sponges produce gemmules, which are groups of archaeocytes surrounded by a tough layer of spicules. Gemmules can survive freezing temperatures and drought. When conditions become favorable, a gemmule grows into a new sponge.

26 End Show 26-2 Sponges Slide 26 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Sexual reproduction involves joining haploid gametes that have been produced by meiosis. Since the zygote contains genes from both parents, the new sponge is not genetically identical to either parent.

27 End Show 26-2 Sponges Slide 27 of 35 Copyright Pearson Prentice Hall Form and Function in Sponges Asexual reproduction, in contrast, does not involve meiosis or the joining of haploid gametes. Asexual reproduction produces offspring that are genetically identical to the parent.

28 End Show 26-2 Sponges Slide 28 of 35 Copyright Pearson Prentice Hall Ecology of Sponges Sponges are important in aquatic ecology. They provide habitats for marine animals such as snails, sea stars, and shrimp.

29 End Show 26-2 Sponges Slide 29 of 35 Copyright Pearson Prentice Hall Ecology of Sponges Sponges containing photosynthetic organisms play an important role in the ecology and primary productivity of coral reefs. The spicules of some sponges look like cross-shaped antennae. They focus and direct incoming sunlight to cells lying below the surface of the sponge—where symbiotic organisms carry out photosynthesis.

30 End Show - or - Continue to: Click to Launch: Slide 30 of 35 Copyright Pearson Prentice Hall 26-2

31 End Show Slide 31 of 35 Copyright Pearson Prentice Hall 26-2 In sponges, a spike-shaped structure made of chalklike calcium carbonate or glasslike silica is a(an) a.spicule. b.archaeocyte. c.choanocyte. d.epidermal cell.

32 End Show Slide 32 of 35 Copyright Pearson Prentice Hall 26-2 An immature stage of an organism that looks different from the adult form is a(an) a.gemmule. b.larva. c.archaeocyte. d.choanocyte.

33 End Show Slide 33 of 35 Copyright Pearson Prentice Hall 26-2 Specialized cells that use flagella to move water through the sponge are a.gemmules. b.pores. c.spicules. d.choanocytes.

34 End Show Slide 34 of 35 Copyright Pearson Prentice Hall 26-2 Sponges are a.detritivores. b.carnivores. c.filter feeders. d.herbivores.

35 End Show Slide 35 of 35 Copyright Pearson Prentice Hall 26-2 Sponges can reproduce a.sexually only. b.asexually only. c.both sexually and asexually. d.by metamorphosis.

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