Chapter 34 Lecture Notes.docx - Lecture 13 Chapter 34...

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Lecture 13 Chapter 34 – Vertebrates Introduction to chordates What is a chordate? The larger group of vertebrates Groups… Chordate phylogeny diagram – pg 699 Animal Body Plans - Protostome vs Dueterostome a. Cleavage b. coelom formation c. fate of blastospore What are Chordates? There are 4 structural characteristics common to all at some point during their development: 1. Notochord – solid cartilaginous rod of support 2. Dorsal, hollow nerve cord – develops in to the central nervous system 3. Pharangeal slits – filter-feeding devices; Respiration (gills) 4. Muscular post-anal tail – used for propulsion
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Sub-phylym: Urochordata Tunicates (ex: sea squirts) Small group (small # of species) Sessile as adults Filter feeders All 4 structural chordate characteristics are displayed only in larval stage = An invertebrate chordate Sub-phylum: Cephalochordata Lancelets – translucent, fish-like Small group Small organisms (1” to 2”) Use cilia to filter feed – fresh water Adults have all 4 chordate characteristics = most resembles the idealized chordate diagram 34.3 on pg 699 Sub-phylum: Craniate Myxini - Hagfish - not a true fish (eel-like) Cartilaginous skull Lack jaws and vertebrae Has good body segmentation Notochord retained in adulthood – strong, flexible rod of cartilage used for locomotion Hox gene duplication Produce slime! – secretes protein that hydrates in water Phylum: Chordata Lampreys Cartilaginous vertebral column around their rod-like notochord Lack jaws Vertebrata Petromyzontida – oldest living lineage of vertebrates. Class – cephalaspidomorphi Gnathostomes - appeared 470 mya Jaws Mineralized skeleton “jaw mouth” fishes Lateral line system Paired fins (true fishes) Shift from filter-feeding to predation Skeletal rods form jaws
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Class: Chondrichthyes Sharks and rays Cartilage fish, but have traces of bone, ex: teeth Little change in 300my, but have speciated Very efficient Predators = life strategy Phylum Chordata: Vertebrata Osteichthyes “Bony fish” – bony endoskeleton Buouancy controlled by a swim bladder Class Actinopterygii Ray finned fish Fins are supported mainly by long, flexible rays Range of lifestyle Class Sarcopterygii
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  • Fall '15
  • Biology, Phylogeny, Vertebrates, Chordate phylogeny diagram, structural chordate characteristics, idealized chordate diagram

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