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BilateriaSlide 2Slide 3Slide 4Protostomia divisionsProtostome Divisions: the Lophotrochozoa and Ecdysozoa.Lophotrochozoa and EcdysozoaSlide 8Slide 9Slide 10“Worms”Acoelomate wormsSlide 13Slide 14Slide 15Slide 16Phylum PlatyhelminthesSlide 18Slide 19Slide 20NutritionSlide 22Slide 23Slide 24Excretion/OsmoregulationSlide 26Nervous system and sense organsSlide 28Slide 29Slide 30Slide 31ReproductionClassification of PlatyhelminthesClass TurbellariaSlide 35Slide 36Slide 37Slide 38Slide 39BilateriaBilateriaHaving completed the radially Having completed the radially symmetrical Cnidarians and symmetrical Cnidarians and Ctenophores we now move on to the Ctenophores we now move on to the remaining animals, all of which are remaining animals, all of which are bilaterally symmetrical (or bilaterally symmetrical (or secondarily radially symmetrical [the secondarily radially symmetrical [the Echinoderms]). Echinoderms]). These are the Bilateria.These are the Bilateria.BilateriaBilateriaAll Bilateria are triploblastic and the All Bilateria are triploblastic and the members are assigned to two major members are assigned to two major groups, which we have already met, the groups, which we have already met, the Protostomia and the Deuterostomia.Protostomia and the Deuterostomia.Deuterostomes include the Echindoerms, Deuterostomes include the Echindoerms, Hemichordates and Chordates.Hemichordates and Chordates.Protostomes include all the other bilateral Protostomes include all the other bilateral invertebrates including Platyhelminthes, invertebrates including Platyhelminthes, Annelida, Mollusca, and Arthropoda.Annelida, Mollusca, and Arthropoda.Protostomia divisionsProtostomia divisionsClassification of invertebrates is in a state of flux for Classification of invertebrates is in a state of flux for several reasons:several reasons:molecular phylogenetic studies have cast doubt on traditional molecular phylogenetic studies have cast doubt on traditional invertebrate classification.invertebrate classification.many invertebrates are soft-bodied so fossils of many groups many invertebrates are soft-bodied so fossils of many groups are rare or unknown, which makes relationships between groups are rare or unknown, which makes relationships between groups hard to decipher.hard to decipher.Traditional major groups of protostomes (acoelomate, Traditional major groups of protostomes (acoelomate, pseudocoelomate and coelomate) appear not to be pseudocoelomate and coelomate) appear not to be monophyletic.monophyletic.For this class, we will use the Deuterostome/Protostome For this class, we will use the Deuterostome/Protostome arrangement and recognize two majors groups of arrangement and recognize two majors groups of Protostomes: the Lophotrochozoa and the Ecdysozoa.Protostomes: the Lophotrochozoa and the Ecdysozoa.Protostome Divisions: the Protostome Divisions: the Lophotrochozoa and Lophotrochozoa and Ecdysozoa.Ecdysozoa.Protostomes are divided into two Protostomes are divided into two large groups the Lophotrochozoa and large groups the Lophotrochozoa and the Ecdysozoa.the Ecdysozoa.The relatedness of phyla The relatedness of phyla withinwithin these these two groups is not entirely clear and two groups is not entirely clear and will likely change in the future.will likely change in the future.Lophotrochozoa and Lophotrochozoa and EcdysozoaEcdysozoaLophotrochozoa: members generally Lophotrochozoa: members generally possess a trochophore larva [free-possess a trochophore larva [free-swimming oval or pyramidal ciliated larva swimming oval or pyramidal ciliated larva with a band of cilia around the body] or a with a band of cilia around the body] or a lophophore [tentacle bearing arm which lophophore [tentacle bearing arm which contains within it an extension of the contains within it an extension of the coelomic cavity].coelomic cavity].Ecdysozoa: members shed their cuticle as Ecdysozoa: members shed their cuticle as they grow they growTrochophore larvahttp://www.microscopy-uk.org.uk/mag/imgjan09/image006.jpgLophophore: characteristic feeding structure of members of theBrachiopoda, Bryozoa and PhoronidaBryozoan lophophore http://www.bryozoans.nl/pictures/figuren/anatomy.jpgLophotrochozoa and Lophotrochozoa and EcdysozoaEcdysozoaLophotrochozoa members:Lophotrochozoa members:Platyhelminthes, Annelida, Mollusca, and Platyhelminthes, Annelida, Mollusca, and a diverse array of “lesser phyla” a diverse array of “lesser phyla” including Nemertea, Gnathostomulida, including Nemertea, Gnathostomulida, Rotifera, and Sipuncula.Rotifera, and Sipuncula.Ecdysozoa members:Ecdysozoa members:Nematoda, Arthropoda and “lesser Nematoda, Arthropoda and “lesser phyla” including Onychophora, phyla” including Onychophora, Tardigrada, and Priapulida.Tardigrada, and Priapulida.““Worms”Worms”The term worm is loosely employed in biology The term worm is loosely employed in biology and is applied to very different animals and is applied to very different animals including the segmented worms (Annelids), including the segmented worms (Annelids), roundworms (pseudocoelomates) and a roundworms (pseudocoelomates) and a variety of acoelomate bilateral animals.variety of acoelomate bilateral animals.““Worm” describes any bilaterally symmetrical, Worm” describes any bilaterally symmetrical, legless, soft-bodied animal at least 2-3 times legless, soft-bodied animal at least 2-3 times as long as it is wide.as long as it is wide.One group of worms traditionally recognized One group of worms traditionally recognized was the acoelomate worms.was the acoelomate worms.Acoelomate wormsAcoelomate wormsThree phyla of acoelomate worms Three phyla of acoelomate worms were traditionally grouped together were traditionally grouped together because they lacked a coelom and because they lacked a coelom and had a solid body filled with had a solid body filled with parenchyma cells:parenchyma cells:Platyhelminthes: flatwormsPlatyhelminthes: flatwormsNemertea: ribbon wormsNemertea: ribbon wormsGnathostomulida: jawed wormsGnathostomulida: jawed wormsBaseodiscus delineatus (Nemertea) http://tolweb.org/images/Nemertea/2489http://tolweb.org/images/Gnathostomulida/2481Acoelomate wormsAcoelomate wormsHowever, molecular evidence based on However, molecular evidence based on ribosomal RNA sequences suggests the ribosomal RNA sequences suggests the


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SUNY Plattsburgh BIO 323 - BILATERIA

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