Lab_report_example-1 - YOUR NAME Planaria and Their...

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YOUR NAME Planaria and Their Regenerative Powers Introduction An invertebrate, by definition, is an animal without a vertebra, what is more commonly know as a backbone. These organisms are very morphologically diverse and live in almost every habitat in the world (Campbell and Reece, 2005). Out of the 35 animal phyla described by biologists, 34 describe invertebrates, and of all the described animal species known to man, 95% are invertebrates (Campbell and Reece, 2005). The invertebrate used in this study is a member of the genus Dugesia , an organism in the phylum Platyhelminthes, more commonly known as flatworms. Platyhelminthes are triploblastic, acoelomates that are bilaterally symmetrical. These organisms are free-living flatworms that generally live in freshwater ponds or streams and feed on smaller animals such as small insects (Reddien and Sánchez Alvarado, 2004; Campbell and Reece, 2005). Since the organisms in this phyla lack a coelom, they do not have a respiratory system or a circulatory system, instead they respire via diffusion (Newmark and Sánchez Alvarado, 2002). Planaria, family Planariidae (class Turbellaria), are very popular specimens in scientific studies due to their regenerative capabilities (Planarium, 2006). Two noteworthy morphological features of Planaria are their two “eyespots” (photoreceptors) located on the anterior, dorsal region (head) of the organism and the opening of the pharynx (mouth) located on the ventral side of the body. Planaria have the ability to regenerate, meaning when a piece of their body is amputated the resulting two pieces “grow back” the lost pieces, creating new Planaria (Lum and Shakhbandaryan, 2006). Something to note is that the cells located just above the photoreceptors and those located at the pharynx are not able to regenerate a complete animal 1
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because they are post-mitotic structures (Newmark and Sánchez Alvarado, 2002); (Campbell and Reece, 2005). Based on this known information, we hypothesize that each piece of the amputated Planaria will most likely regenerate a head, a tail, or both, depending on which is needed to complete a whole organism. In the case where the Planaria will be cut into 3 pieces, one piece (the anterior piece) will probably grow a tail, another (the posterior) will grow a head and the
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This note was uploaded on 09/27/2008 for the course BISC 120Lg taught by Professor 11:00-01:50pm during the Fall '06 term at USC.

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Lab_report_example-1 - YOUR NAME Planaria and Their...

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