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Nematoda Jenny Brooke David Thursday, May 25, 2017 Period 1 http://www.stanford.edu/group/parasites/ParaSites2006/Loiasis/Home.html Sample Animals and Pictures • Caenorhabditis elegans • Tricinella spiralis David Dallas-Orr Body Cavity (coelom) present or absent • Have a coelom • Nutrients are transported in the fluid in the pseudocoelom • The fluid under high pressure David Dallas-Orr Body Symmetry • Bilaterally symmetrical David Dallas-Orr Nervous System • Nematodes have a reasonably well developed nervous system. • This is comprised of a circum-pharyngeal nerve ring made up from 4 nerve ganglia from which 6 longitudinal nerves extend down through the body • There are also 6 shorter nerves which extend forwards towards the mouth. David Dallas-Orr Circulatory System • Lacks a circulatory system David Dallas-Orr Digestive System • Alimentary canal: digestive canal issuing a track from mouth to anus http://classes.seattleu.edu/biology/biol235/ho din/nematodePriapulidGroup/nematodes/for mAndFunction.htm#excretory Pathway of food: mouth (stoma) pharynx intestines rectum anus Jenny Kim Excretory System • Nitrogenous waste is excreted through body wall • Rennette gland to excrete salt to maintain osmoregulation. Jenny Kim Locomotion/Musculature • Only longitudinal muscles for movement • Moves by undulations or wave-like motions of the body. This produces a thrashing movement. http://classes.seattleu.edu/biology/biol235/ho din/nematodePriapulidGroup/nematodes/loco motion.htm Jenny Kim Skeletal Type • Hydostatic skeleton: Non-compressible fluid enclosed and pressurized in body cavity. • Tough cuticle that coats body • Cylindrical and unsegmented http://www.newscientist.com/gallery/mg20327161300-enemywithin-human-parasites/3 Jenny Kim SENSORY STRUCTURES/FEATURES • Nematodes have peripherally located sense organs. • Recent studies revealed the presence of true cilia in nerve processes connected with sensory organs. • The body is covered in sensory bristles and papillae that provide a sense of touch. http://www.ucmp.berkeley.edu/phyla/ecdysozoa/ nematoda.html Brooke Goycochea. REPRODUCTION • A female may deposit • Different species of 100,000 or more nematodes have fertilized eggs per various ranges of day. modes of reproduction. • Reproduction is usually sexual and most nematode species are dioecious. Some species, however, are hermaphroditic. http://w3.rennes.inra.fr/umrbio3pE/equi pes/nematodes/images/lamelle-460.jpg Brooke Goycochea. GAS EXCHANGE • Have an alimentary canal but no circulatory system. • Respiration and gas exchange occur by diffusion across the body wall. • Both anaerobic and aerobic metabolism is http://www.ars-grin.gov/ars/SoAtlantic/fp/stpp/burelle/nematode.jpg common. Brooke Goycochea. Unique Features of Nematodes • About 25,000 species are known but about 20 times more exist. There is little known about each nematode species even though they are numerous. • It is said that if nothing but nematodes existed, they would preserve the outline of Earth and its many features. • Humans host at least 50 nematode species. http://www.ucmp.berkeley.edu/phyla/ecdysozoa/ne matodesm.jpg Brooke Goycochea Quiz • 1. Which of the following do not have a Hydrostatic skeleton for support? • • • • A. Cnidaria B. Platyhelminthes C. Nematoda D. Annalida • 2. Which of the following have a circulartory system? • • • • A. Cnidaria B. Platyhelminthes C. Nematoda D. Annalida • 3. Which of the following does not has a different body symmetry in the group listed below? • • • • A. Cnidaria B. Mollusca C. Nematoda D. Chordata • What type of body symmetry does each of the different phyla have? (listed above) Quiz • 1. Which of the following do not have a Hydrostatic skeleton for support? • • • • A. Cnidaria B. Platyhelminthes C. Nematoda D. Annalida • 2. Which of the following have a circulartory system? • • • • A. Cnidaria B. Platyhelminthes C. Nematoda D. Annalida • 3. Which of the following does not has a different body symmetry in the group listed below? • • • • A. Cnidaria B. Mollusca C. Nematoda D. Chordata • • What type of body symmetry does each of the different phyla have? (listed above) A - Radial B,C,D – Bilateral Bibliography for beginning pix • http://riddlelab.msl.ubc.ca/images/maincelegans.jpg • http://images.google.com/imgres?imgurl=http://workforce.cup.edu/b uckelew/images/Trichinella%2520spiralis%2520male.jpg&imgrefurl= http://workforce.cup.edu/buckelew/Trichinella%2520spiralis%2520m ale.htm&usg=__N5OebYUengR9rzBklrnegm5b0Q=&h=512&w=640&sz=27&hl=en& start=1&um=1&itbs=1&tbnid=To3n2v9H1z6ALM:&tbnh=110&tbnw= 137&prev=/images%3Fq%3DTrichinella%2Bspiralis%26um%3D1% 26hl%3Den%26sa%3DG%26ndsp%3D20%26tbs%3Disch:1 • http://www.cals.ncsu.edu/course/zo150/mozley/fall/nematode.jpg • http://www.nottingham.ac.uk/bennettlab/nematode.jpg • http://web.pml.ac.uk/nematode/pictures/images/nematode5.jpg