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The Vertebrate Genealogy. What is a chordate? There are 4 anatomical structures that appear during some point during the animal’s lifetime: 1. Notochord.

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Presentation on theme: "The Vertebrate Genealogy. What is a chordate? There are 4 anatomical structures that appear during some point during the animal’s lifetime: 1. Notochord."— Presentation transcript:

1 The Vertebrate Genealogy

2 What is a chordate? There are 4 anatomical structures that appear during some point during the animal’s lifetime: 1. Notochord – long flexible tube between the gut and the nerve cord - becomes gelatinous material between vertebrae in humans 2. Dorsal, hollow nerve cord – becomes CNS 3. Pharyngeal slits 4. Muscular postanal tail – most chordates have a tail that extends beyond the anus

3 What is a chordate?

4

5 Survey of Vertebrate Classes Fishes: Agnatha, Chondrichthyes, Osteichthyes Tetrapods: Amphibia, Reptilia, Aves, Mammalia Amniotes: Reptilia, Aves, Mammalia Have a shelled water-retaining egg

6 Class Agnatha Sample organisms: Hagfishes, lampreys Jawless vertebrates Feed by sucking blood after clamping onto prey or by scavenging Do not have paired appendages

7 Class Chondrichthyes Sample organisms: sharks and rays Cartilaginous fishes – have relatively flexible skeletons made of cartilage rather than bone Most sharks are carnivorous and have acute senses

8 Class Osteichthyes Bony fishes Have hard skeletons (due to ossification) Sample organisms: perch, trout Breathe by drawing water over 4-5 pairs of gills covered by operculum (protective flap) Most bony fishes are oviparous Females lays large numbers of eggs, fertilization occurs externally

9 Class Osteichthyes

10 Class Amphibia The first vertebrates (tetrapods) on land Amphibians must deposit their shell-less eggs in water Sample organisms: frogs & salamanders Amphibian = “two lives” Tadpole – larval stage Metamorphosis occurs Frog – legs develop Salamanders – have tails Frogs – do not have tails

11 The Amniotic Egg The amniotic egg is a reproductive adaptation that allowed terrestrial vertebrates to complete their life cycles on land The shell prevents the egg from drying out 4 layers of protection: Amnion – prevents dehydration, cushions shocks Yolk Sac – stockpile of nutrients Allantois – disposal sac for certain metabolic wastes Chorion – gas exchange

12 Class Reptilia Sample organisms: lizards, snakes, turtles, crocodiles Reptiles have scales made of keratin that cover their skin Obtain oxygen with their lungs Fertilization occurs internally Most reptiles lay amniotic eggs on land Ectotherms – body temperature fluctuates with the environment

13 Class Aves Birds are tetrapods with feathers Their forelimbs are modified as wings Sample organisms: owl, sparrow, penguin, eagles Lay amniotic eggs Endothermic – regulate their own body temps. Anatomy adapted for flight Form & function

14 Class Mammalia Mammals have hair Endothermic Mammary glands that produce milk Most mammals are born, not hatched Three major groups: Monotremes – lay eggs platypuses, echidnas Marsupials – complete development in a maternal pouch Kangaroos, koalas, opossums Placental mammals – complete development within the uterus, joined to the mother by the placenta Sheep, bats, elephants, humans


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