1. Sponges, Cnidarians and Ctenophores
Chapter 33
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Lbell06
Chapter 33 P. Porifera

2. P. Porifera (pore-bearer)
Invertebrates are animals that do not have backbones. Invertebrates include more than a million species. About 97% of all known animal species are intervetebrates among the simplest of which are sponges.
Chapter 33 P. Porifera

3. Objectives 33.1 Describe the basic body plan of a sponge
Describe the process of filter feeding in sponges
Contrast the process of sexual and asexual reproduction in sponges
Chapter 33 P. Porifera

4. Body Plan of Sponges Aquatic animals Simple organisms
Heterotrophic, multicellular, do not have cell walls
No gastrula stage, less structure and organization
No true tissues
5,000 named species, 150 fresh water
Once believed to be plants
Tend to be sessile- they don’t move, they remain attached to a hard surface
Grow in many shapes, sizes, and colors
Chapter 33 P. Porifera

5. Body Plan of Sponges cont
Can be small or very large
Have two main layers of cells
Separated by a jellylike substance called mesohyl
Body wall forms a hollow cylinder that is closed at the bottom and open at the top
Interior of the cylinder is lined with flagellated cells called choanocytes or collar cells, this draws water into the sponge into pores called ostia and then the water leaves by the osculum (opening at the top of the sponge)
Spongin and spicules are the skeleton like structures that give the sponge its shape and support
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7. Feeding and Digestion in Sponges
Don’t forget they are sessile- they are filter feeders
The flagella of the choanocytes trap plankton and other tiny organisms in the small hairlike projections
Amoebocytes are cells that have the ability to crawl about the body wall to deliver nutrients
Chapter 33 P. Porifera

8. Reproduction in sponges
Asexually
forming small buds that break off and live separately
Gemmules-food-filled ball of amoebocytes surrounded by a protective coat made of organic materials and spicules
buds are produced during droughts or cold weather
Have the ability to regenerate or regrow missing cells, tissues, and organs
Chapter 33 P. Porifera

9. Reproduction in sponges
Sexually-
Sperm travels from one sponge to the next
Sperm travels to choanocytes amoegocytes to an egg in the mesohyl
The egg is fertilized and turns into a larva and attaches to the surface and grows into an adult sponge
Some are separate sexes, some are hermaphrodites
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12. 33.2 objectives Describe the basic body plan of a cnidarians
Summarize how cnidarians feed
Describe the nervous system of cnidarians
Identify and give examples of the four classes of cnidarians
Describe the common characteristics of ctenophores
Chapter 33 P. Porifera

13. P. Cnidaria and P. Ctenophora
Cnidaria and Ctenophora are two phlya of radially symmetrical invertebrates. The animals in these phyla are more complex than the sponges. Their cells are organized into tissue, and they have a few simple organs. All members of the phyla Cnidaria and Ctenophora are aquatic and most live in the ocean.
Chapter 33 P. Porifera

14. Body Plan of Cnidarians
Hydra, jellyfish, flowerlike coral
Two shapes-
1. bellshaped- medusa, swimming
2. vaseshaped- polyp, sessile (nonmoving)
Chapter 33 P. Porifera

15. Body Plan of Cnidarians cont
Has two cell layers:
1. outer epidermis
2. inner gastrodermis
3. mesoglea- jelly like material in between the two layers
4. gastrovascular cavity- hollow gut with mouth
5. tentacles- flexible extensions surrounding the mouth
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17. Feeding and Defense in Cnidarians
Cnidocytes- (NIE-duh-siets) specialized cells used for defense and capturing prey, it contains a Nematocyst- long filament coiled up inside, it will puncture the object and inject poison
Feeding- the tentacles capture small animals and paralyze them and eat them
Both food and waste enter and exist same opening (mouth)
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19. Nervous system in cnidarians
Nerve net- web of interconnected nerve cells that control nervous responses
No true brain
Some organisms have a medusa which is just a bunch of clustered nerve cells in rings around the edges of the bell-shaped body (they act as one)
Controls all body functions, swimming eating, and defense
Chapter 33 P. Porifera

20. Classification of Cnidarians
4 major classes
Hydrozoa
Cubozoa
Scyphozoa
anthozoa
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21. C. Hydrozoa 3700 species Most colonial
Some only live as polyps or medusa, some will alternate
Examples are: Obelia, hydra
Sexual reproduction occurs in the fall
Hermaphroditic
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22. C. Cubozoa
Box jellies, sea wasp, have tentacle or group of tentacles found at each corner of the “box”
Used to be grouped with Schyphozoa
Cubed-shaped medusa
Polyp stage is rarely seen
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23. C. Scyphozoa “cup animals” Dominant from of the life cycle is medusa
Can be poisonous
Portuguese man-of-war
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24. C. Anthozoa “flower animals” 61000 marine species
Sea anemones- polyps, attached to rocks, symbiotic relationship with clownfish
Corals- small polyps live in colonies
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25. P. Ctenophora
Comb holder, 8 comblike rows of cilia that run outside the animal, comb jellies
100 species of marine animals
Chapter 33 P. Porifera

26. P. Ctenophora Differ from jellyfish and other cnidarians
Don’t pulsate, bearing cilia
No cnidocytes, they have colloblasts which secrete a sticky substance that binds to prey, located on two tentacles
Sensory structure called apical organ at then of the body
Hermaphroditic
Bioluminescene- ability to produce light by a chemical rxn
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27. Lab
1. Incurrent canal
2. Radial canal
3. Spongocoel
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