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Phylum Chordata

Phylum Chordata

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Phylum Chordata

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  1. Phylum Chordata • Deuterostome development • Dorsal hollow nerve cord from ectoderm • Notochord • Stiff rod between nerve cord & intestine • Support for muscular movements • Pharyngeal gill slits • Slits allow water to escape before stomach • Post-anal tail

  2. Phylum Chordata • Subphylum Urochordata • Tunicates (sea squirts) • Sessile adults filter water with gill slits • Incurrent & excurrent siphons • Subphylum Cephalochordata • Lancelets • Mobile adults bury body in sand w/ mouth out • Filter-feed across gill slits

  3. Subphylum Vertebrata • Cranium around brain • Cartilaginous or bony vertebrae around nerve cord • Except hagfishes • Diversity of vertebrates • Superclass Agnatha (hagfish & lampreys) • Jawless fish • Lack paired appendages • Cartilaginous skeleton • Superclass Gnathostomata (jawed mouth)

  4. Vertebrata • Class Chondrichthyes (sharks, rays, & skates) • Cartilaginous fishes • Some are oviparous (release eggs) • Some ovoviviparous (release after hatching) • Some are viviparous (nourished by placenta)

  5. Vertebrata • Class Osteichthyes • Bony fishes (ossified skeleton) • Ray-finned, Lobe-finned, & lung fishes • Ray-finned has most species • Gills covered by operculum • Swim bladder regulates buoyancy

  6. Terrestrial vertebrates • Class Amphibia • Amniotes • Class Reptilia • Class Aves • Class Mammalia

  7. Class Amphibia • Tetrapod vertebrates • Ectothermic • Developing eggs & larva need aquatic environment • Gas exchange through skin, gills, lungs, &/or mouth • Orders • Order Anura (frogs & toads) • Order Urodela (salamanders) • Also caecilians

  8. Amniotes • Amniotic egg contains extra-embryonic membranes • Amnion: surrounds embryo • Allantois: for waste disposal • Yolk sac: stored nutrients for embryonic growth • Chorion: surrounds all these (exchanges gases) • Allow reproduction away from water

  9. Class Reptilia • Internal fertilization • Leathery shelled amniotic eggs • Some have live birth (ovovivipary & vivipary) • No larval stage of development • Dry, scaly skin • Lung respiration • Nitrogenous waste is uric acid • Ectothermic

  10. Class Reptilia • Order Testudines • Sea turtles, tortoises, & terrapins • Order Squamata • Lizards & Snakes • Order Crocodilia • Crocodiles, caimans, & alligators

  11. Class Aves • Hard-shelled egg • Adapted for flight • Hollow bones • Endothermic • Air sacs in addition to lungs • No teeth (gizzard does grinding) • Feathers • Bipedal (forelimbs are wings)

  12. Class Aves • 29 (or so) living orders with >8,500 species • Order Anseriformes (Ducks, geese, & swans) • Order Piciformes (Woodpeckers) • Order Falconiformes (Hawks, flacons, eagles) • Order Galliformes (Chickens, turkeys, etc.) • Order Passeriformes (songbirds) • Sparrows, finches, cardinals, mockingbirds, jays, crows, wrens, thrushes, etc

  13. Class Mammalia • Endothermic • Hair • Mammary glands • Some oviparous (egg-laying) • Monotremes (platypus & echidna) • Most viviparous (nourished by placenta) • Marsupials • Eutherians

  14. Class Mammalia • About 4,500 species in 20 orders • Order Monotremata (platypus & echidnas) • Order Marsupialia (opossums, kangaroo, koala, etc) • Order Chiroptera (bats) • Order Carnivora (lions & tigers & bears!, also weasels, dogs, raccoons, seals, etc) • Order Cetacea (whales, dolphins) • Order Rodentia (rats, squirrels, beaver, etc.) • Order Primates (lemurs, monkeys, apes, & you)

  15. Order Primates • Prosimians (e.g. lemurs) • Old-world monkeys (non-prehensile tails) • New-world monkeys (prehensile tails) • Apes • Gibbons • Orangutans • Chimpanzees • Gorillas • Humans

  16. Homonid evolution • Bipedalism • Brain size • Reduction in sexual dimorphism • Perhaps with switch to monogamy • Extended parental care • Tool use • Split from other ape ancestor some 5-7 million y.a. • Diversified into Australopithecus and Homo