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Cnidaria. General Characteristics The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle The name Cnidaria comes from the Greek.

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Presentation on theme: "Cnidaria. General Characteristics The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle The name Cnidaria comes from the Greek."— Presentation transcript:

1 Cnidaria

2 General Characteristics The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle They have stinging cells called nematocysts They have stinging cells called nematocysts An exclusively aquatic phylum An exclusively aquatic phylum Tissue level organization Tissue level organization Generally, their bodies are two cell layers thick Generally, their bodies are two cell layers thick Radial symmetry; Little specialization; Pseudocoelomate Radial symmetry; Little specialization; Pseudocoelomate Extracellular digestion Extracellular digestion Hydrostatic skeleton Hydrostatic skeleton Both asexual and sexual reproduction Both asexual and sexual reproduction External fertilization External fertilization One opening, the mouth One opening, the mouth http://fotokudra.lt/files/I261542.jpg

3 http://www.wallawalla.edu/academics/departments/b iology/rosario/inverts/Cnidaria/Class- Hydrozoa/HydroidPolyps/Obelia_dichotoma.html http://kentsimmons.uwinnipeg.ca/1 6cm05/16labman05/lb5pg3_files/h ydra3.jpg Class Hydrozoa (Hydroids) HydraObelia http://www.biology.iastate.edu/Courses /211L/Cnidar/%20CnidINDX.htm Goneonemus

4 http://seanet.stanford.edu/HydroScyphozoa/aurelia_lab580.jpg Class Scyphozoa (Jellyfish) Aurelia

5 http://www.valdosta.edu/~jlgoble/Sea%20Anemone%20Diadumene%20Dia%2030c m%201.JPG Class Anthozoa (Corals & Sea Anemone) Sea Anemone

6 Class Cubomedusa (Box Jellyfish) http://thestashbox.files.wordpress.com/2009/02/226boxjellyfish1.jpg Box Jelly

7 Body Plan Tissue level of organization Outer covering (epidermis), inner gasterodermis, non-cellular mesoglea between the two; Diploblastic, body and tentacles consists of two cell layers Possess stinging structures, nematocysts, housed in cells called cnidocytes; Single body opening, the mouth Radial symmetry Two body forms Polyp: cylindrical with tentacles at one end; Sessile (non-motile) but some capable of locomotion; mouth points upward; EX: The Hydra Medusa: Free swimming; Bell shaped; Swim by undulations of their bell; Thicker mesoglea mouth-side down; EX: The Jellyfish Some cnidarians exist only in polypoid or medusoid form, others alternate between the two Both diploid so not true alternation of generations

8 Body Plan cont. http://biology.unm.edu/ccouncil/Biology_203/Images/SimpleAnimals/cnidariaDiagram.jpeg

9 http://www.arcodiv.org/cnidarians.html Feeding Carnivorous or filter feeders Carnivorous or filter feeders Medusa do not hunt for prey, use “sit-and-trap” method Medusa do not hunt for prey, use “sit-and-trap” method Uses cnidae and toxins to stun and kill prey Uses cnidae and toxins to stun and kill prey Sessile ployps depend on organisms that come in contact with tentacles Sessile ployps depend on organisms that come in contact with tentacles Tentacles have stinging cells (cnidocytes) that contain small harpoons called nematocysts Tentacles have stinging cells (cnidocytes) that contain small harpoons called nematocysts Harpoon propelled by osmotic pressure, spears prey and draws it back to hydra Harpoon propelled by osmotic pressure, spears prey and draws it back to hydra Both have a ring of tentacles around the mouth Both have a ring of tentacles around the mouth Extracellular digestion; gut cavity for digestion, lining cells engulf food by phagocytosis Extracellular digestion; gut cavity for digestion, lining cells engulf food by phagocytosis Enzymes secreted from the gastrodermis break down the food Enzymes secreted from the gastrodermis break down the food http://www.nick.com/multimedia/binits08 games/spongebob-jellyfishin-game.png

10 Respiration Contains no respiratory system Contains no respiratory system This image depicts the internal structure of a jellyfish (a Medusae cnidaria). Because the great majority of cells are directly in contact with the ocean water, a complicated respiratory system is not needed. http://www.arcodiv.org/cnidarians.html

11 Circulation No circulatory system (blood vessels) Majority of cells come in direct contact of seawater Have gastrovascular cavity; inner cells exposed to water Only two cell layers thick, all cells exposed to water for nutrient and gas exchange http://www.connecticutvalleybiological.com/images/vc1336v.jpg

12 http://www.arcodiv.org/cnidarians.html Excretion Contains no excretory organs Gastrovascular cavity serves for gas exchange and digestion Gas exchange takes place directly across the surface of their body and waste is released either through their gastrovascular cavity or by diffusion through their skin No anus Excretes through mouth, only opening

13 Response Simple net like nervous system Simple net like nervous system Coordinates contraction of muscles; Little central control Coordinates contraction of muscles; Little central control http://www.arcodiv.org/cnidarians.html

14 http://www.aboutmyplanet.com/files/2008/12/800px- Jellyfish_in_the_Montery_Bay_Aquarium-resized.jpgMovement Polyp Sits on basal disk, used to glide around with help of mucus secretions Some can somersault, bending over and attaching itself to substrate by its tentacles and looping over to new location If polyp detaches itself from substrate, it can float to surface Medusae Outer layer, epithelium, contains specialized epitheliomuscular cells, each can contract individually These cells form muscular rings around the bell shape of the jellyfish; allows the animal to propel through water

15 Reproduction Polyps reproduce asexually (budding and fragmentation) Polyps reproduce asexually (budding and fragmentation) Medusae reproduce sexually Medusae reproduce sexually Fertilization external Fertilization external Alternation between medusa, sexually reproductive stage, and polyp, the asexual stage Alternation between medusa, sexually reproductive stage, and polyp, the asexual stage Class Anthozoa has no medusa stage Class Anthozoa has no medusa stage Medusae has a distinct larval stage which is planktonic; called planulae; multicellular, pear-shaped, entirely ciliated Medusae has a distinct larval stage which is planktonic; called planulae; multicellular, pear-shaped, entirely ciliated Jellyfish have separate male and females Jellyfish have separate male and females Medusae stage is dominant Medusae stage is dominant Some exhibit the medusa form throughout their life while others first pass through other phases before maturing into the medusa form Some exhibit the medusa form throughout their life while others first pass through other phases before maturing into the medusa form

16 Reproduction http://universe-review.ca/I10-82-cnidaria.jpg

17 Works Cited "Introduction to Cnidaria." UCMP - University of California Museum of Paleontology. Web. 15 Apr. 2010.. "Introduction to Cnidaria." UCMP - University of California Museum of Paleontology. Web. 15 Apr. 2010.. "Cnidarians." W. Fielding Rubel School of Business: Bellarmine University. Web. 16 Apr. 2010.. "Cnidarians." W. Fielding Rubel School of Business: Bellarmine University. Web. 16 Apr. 2010.. "The Anemones, Corals and Jellyfish (Phylum Cnidaria)." The Earth Life Web. Web. 19 Apr. 2010.. "The Anemones, Corals and Jellyfish (Phylum Cnidaria)." The Earth Life Web. Web. 19 Apr. 2010.. Klappenbach, Laura. "Diet - Cnidarian Diet and Eating Habits." Animals Wildlife - Animal Facts, Animal Pictures, Habitat Facts, Evolution and Zoology. Web. 20 Apr. 2010.. Klappenbach, Laura. "Diet - Cnidarian Diet and Eating Habits." Animals Wildlife - Animal Facts, Animal Pictures, Habitat Facts, Evolution and Zoology. Web. 20 Apr. 2010.. "The Noncoelomate Animals." Biology. Sixth ed. Boston: McGraw Hill, 2002. 886-89. Print. "The Noncoelomate Animals." Biology. Sixth ed. Boston: McGraw Hill, 2002. 886-89. Print.

18 Works Cited (Pictures) "Multi-cell Organisms." A Review of the Universe. Web. 16 Apr. 2010.. "Multi-cell Organisms." A Review of the Universe. Web. 16 Apr. 2010.. "Simple Animals." Web. 19 Apr. 2010.. "Simple Animals." Web. 19 Apr. 2010.. "New Page 1." Virtual Microscope Home Page. Web. 19 Apr. 2010.. "New Page 1." Virtual Microscope Home Page. Web. 19 Apr. 2010.. "Obelia Dichotoma." WWU: On Campus. Web. 19 Apr. 2010.. "Obelia Dichotoma." WWU: On Campus. Web. 19 Apr. 2010.. "Gonionemus." Biology Program at ISU. Web. 19 Apr. 2010.. "Gonionemus." Biology Program at ISU. Web. 19 Apr. 2010.. "Hydrozoa & Scyphozoa." SeaNet. Web. 19 Apr. 2010.. "Hydrozoa & Scyphozoa." SeaNet. Web. 19 Apr. 2010.. "Search Results | SpongeBob.com." SpongeBob.com | SpongeBob SquarePants Episodes, Games, & Pictures. Web. 20 Apr. 2010.. "Search Results | SpongeBob.com." SpongeBob.com | SpongeBob SquarePants Episodes, Games, & Pictures. Web. 20 Apr. 2010.. "Anemone." Valdosta State University. Web. 19 Apr. 2010.. "Anemone." Valdosta State University. Web. 19 Apr. 2010.. "Foto KÅ«dra - Fotografija - Cnidaria Scyphozoa II." FotoKÅ«dra - Fotografija | KÅ«ryba | Bendravimas. Web. 20 Apr. 2010.. "Foto KÅ«dra - Fotografija - Cnidaria Scyphozoa II." FotoKÅ«dra - Fotografija | KÅ«ryba | Bendravimas. Web. 20 Apr. 2010.. "Jellyfish Take Over Ocean: A Dangerous Warning Sign." Go Green. Web. 20 Apr. 2010.. "Jellyfish Take Over Ocean: A Dangerous Warning Sign." Go Green. Web. 20 Apr. 2010.. Hopcroft, Russ. "Cnidarians - Jellyfish and Kin." Arctic Ocean Diversity. Census of Marine Life, 4 Jan. 2008. Web. 20 Apr. 2010. Hopcroft, Russ. "Cnidarians - Jellyfish and Kin." Arctic Ocean Diversity. Census of Marine Life, 4 Jan. 2008. Web. 20 Apr. 2010.


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