BIOl 152 1st Edition Lecture 24 Outline of Last Lecture I Lophotrochozoa a Platyhelminthes b Mollusca c Annelida II Ecdysozoa a Nematodes b Arthropods III Deuterastomes a Echinodermata Outline of Current Lecture I Chordates II Cranium III Vertebrates IV Gnathastomes V Ostheichthyans VI Lobe fins VII Tetrapods VIII Amniotes Current Lecture I II III Chordates The hallmarks of the chordates are they contain notochords an endoskeleton Dorsal hollow nerve cord pharyngeal gills and a post anal tail The clades of the chordates are the Cephalochordate the tunicate and the cranium The Cephalochordate is commonly known as lancelets is mostly marine and use the pharyngeal gills to concentrate food and gas exchange and are filter feeders The tunicates are the sister taxa to the craniate and are mostly marine and are also filter feeders Cranium The Cranium is chordates and a synapamorphy is that they have neural crest cells that help create bone and cartilage of the head Cranium refers to their skull Vertebrates A synapamorphy is that they contain vertebral column that surrounds the dorsal hollow nerve cord and provide the organisms with protection These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V VI VII VIII Gnathastomes Organisms in this clade contain jaws that arose from the modification of pharyngeal gill arches They contain mineralized skeletons and paired appendages Examples are sharks and rays Ostheichthyans These organisms contain lungs or lung derivatives that are derived from the gut They have hard bony calcified skeletons They have swim bladders that allow them to stay afloat and not sink Lobe Fins These organisms have lobed pectoral fins and the other characteristics of craniates and chordates Tetrapods These organisms contain four limbs with digits and signified the movement from water to land The first land vertebrates the amphibians required moist habitat to lay their eggs and the gas exchange was through their skin Amniotes These organisms contain an amniotic egg This egg is specialized and allowed for the diversification of land species The shell protects the embryo from drying out and acts as a shock absorber The egg also allows for gas exchange Mammalians are a class in this clade and contain mammary glands and hair They have placenta that is an intimate connection between mother and embryo it is highly vascularized The placenta provides nutrients and gasses to the embryo
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