8.+Cnidarian+A.K.A.+Coelenterata

Cnidarian A.K.A. Coelenterata Topics -Coelenterata have radial symmetry and are multicellular -They have large tentacles, which are utilized for locomotion and food capturing -They can reproduce asexually or sexually
 * 1. Classification/Diagnostic characteristics**

- Not really harmful to humans, some can induce a painful sting - When extracted, the venom can be used for medicine as a heart-stimulant or for its anti-inflammatory properties
 * 2. Relationship to humans**

Cnidarians live in marine and freshwater ecosystems. The species of cnidarians vary greatly, from corals to jellyfish and they are most abundant and diverse in tropical waters.
 * 3. Habitat and Niche**

- They have tentacles with stinging cells called nematocysts.The nematocysts "sting" the prey and drive off enemies.
 * 4. Predator Avoidance**

- Captures prey with stinging tentacles and pull them into gastrovascular cavity - Enzymes digest prey, and nutrients absorbed - Mouth is used for both ingestion and excretion - Digestion is both intracellular and extracellular - The endodermal cell of some corals, hydras, and sea anemones contain single-celled golden-brown algae, called zooxanthellae, or green algae, called zoochlorellae, and the cnidarians can't digest these algae but derive nutrients, such as glucose and oxygen, from them.
 * 5. Nutrient Acquisition**

- Medusae (fully grown jellyfish) produce polyps - Polyp is anchored in place - Polyps mature, and produce medusae asexually - Medusae becomes mobile - They reproduce sexually, with the sperm and egg joining to make a larva that attaches to the bottom to make a polyp. - Then the polyp breaks off to form a medusa - Coelenterata also utilize a form of asexual reproduction - May have been the first organisms to reach a tissue level of organization. - Range in size from one millimeter wide to 1.8 meters wide.
 * 6. Reproduction and Life Cycle**
 * [[image:Lucas2001Fig1.gif]]
 * 7. Growth and Development**

- They are diploblast animals, i.e, they have only two embryonic cell layers. They have only an epidermis and gastrodermis. Mesogloea, a jelly like substance, is present between the two layers. - Their body form is radially symmetrical with a single opening, the hypostome, surrounded by sensory tentacles equipped with either nematocysts or colloblasts to capture mostly planktonic prey. (1) - The tissues are formed by cells which together form a thin body wall surrounding the organ cavity. (last link) The above body layout comparison reveals more into the relationship between polyp and medusa stages of each individual's life. The outward growth of the hypostome must have evolved to know which direction would allow maximum water flow over its surface, much like plant seeds use gravity in order to know which direction to grow and thus sprout. - The movement of the cnidarian depends upon which of the four main groups a particular cnidarian belongs to. Those groups are the Anthozoa (corals and anemones) which are non-moving and the Scyphozoa (jellyfish), Hydrozoa (mainly freshwater cnidarians) and Cubozoa (box jellies). The jellyfish, the most abundant form of cnidarian, moves using several different techniques including tides, jet propulsion (most jellyfish) and using cilia cells that move rapidly to "row" the jellyfish through the water (as done by the comb jellyfish). - They have nutritive muscular cells that also have contractile fibers. The fibers move the materials in and out of the gastrovascular cavity. Ring like contractions move along the body wall.
 * 8. Integument**
 * 9. Movement**

- Cnidarians do not sense the environment in the traditional way because they do not have a brain or groups of nerve cells; instead, their nerve system is a network spanning throughout their body.
 * 10. Sensing the Environment**

- Respiration and excretion are accomplished by simple diffusion. -In direct diffusion, Coelenterata absorb oxygen from the surrounding area, which is then diffused into the organism through the gastrovascular cavity, and carbon dioxide is expelled out of the organism.
 * 11. Gas Exchange**

- Undigested waste exits through same opening that food enters
 * 12. Waste Removal**

- Have the ability to "sting" potential predators, giving them an evolutionary advantage.
 * 13. Environmental Physiology**

- Do not have any systems for this purpose, utilizing diffusion into the water
 * 14. Internal Circulation**

Little is known about Cnidarian endocrine systems, but hormones similar to those of vertebrates have been identified in Cnidarian tissue samples.
 * 15. Chemical Control**

1. How do these organisms remove waste from their systems? - These organisms remove waste from their systems through the same opening that their food enters. 2. What is unusual about these organisms' sensory abilities? - They don't have a central nervous system or brain. 3. How many cell layers do they have, and what are their names? - They have an epidermis and a gastrodermis. 4.How do these organisms defend themselves from predators? - Tentacles with stinging nematocyst cells. 5. How does the comb jellyfish move? - Rapidly moving cilia.
 * Review Questions:**


 * Sources:**

http://www.tutorvista.com/content/biology/biology-iii/animal-kingdom/phylum-coelenterata.php http://biologyboom.com/%EF%BB%BFphylum-cnidaria-coelenterata/ https://www.britannica.com/animal/cnidarian http://ic.galegroup.com/ic/scic/ReferenceDetailsPage/ReferenceDetailsWindow?disableHighlighting=false&displayGroupName=Reference&currPage=&scanId=&query=&docIndex=&source=&prodId=SCIC&search_within_results=&p=SCIC&mode=view&catId=&u=mlin_s_sharonhs&limiter=&display-query=&displayGroups=&contentModules=&action=e&sortBy=&documentId=GALE%7CCV2641700054&windowstate=normal&activityType=BasicSearch&failOverType=&commentary= http://www.biologydiscussion.com/invertebrate-zoology/metazoa/coelenterata-general-characters-tissues-and-corals-metazoa/28743 [] https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Coelenterata.html (1) https://www.britannica.com/animal/cnidarian http://earthsky.org/earth/how-do-jellyfish-swim http://www.biologydiscussion.com/invertebrate-zoology/metazoa/coelenterata-general-characters-tissues-and-corals-metazoa/28743 https://www.britannica.com/animal/cnidarian http://www.biologydiscussion.com/invertebrate-zoology/metazoa/coelenterata-general-characters-tissues-and-corals-metazoa/28743 Ann M. Tarrant; Endocrine-like Signaling in Cnidarians: Current Understanding and Implications for Ecophysiology, Integrative and Comparative Biology, Volume 45, Issue 1, 1 January 2005, Pages 201–214, []

https://www.ck12.org/biology/Cnidarian-Reproduction/lesson/Cnidarian-Reproduction-Advanced-BIO-ADV/ http://www.asnailsodyssey.com/LEARNABOUT/JELLYFISH/jellyRepr.php http://mesosyn.com/Cnidaria-a.png