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CHORDATES

CHORDATES. 4 Defining Characteristics. 1. Notochord - extends through length of the body as a simple skeleton 2. Dorsal, hollow nerve cord 3. Pharyngeal gill slits 4. Muscular postanal tail. SUBPHYLUM UROCHORDATA tunicates Adults sessile

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CHORDATES

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  1. CHORDATES

  2. 4 Defining Characteristics 1. Notochord - extends through length of the body as a simple skeleton 2. Dorsal, hollow nerve cord 3. Pharyngeal gill slits 4. Muscular postanal tail

  3. SUBPHYLUM UROCHORDATA • tunicates • Adults sessile • Free swimming larvae; only larvae have all 4 defining characteristics

  4. SUBPHYLUM CEPHALOCHORDATA • lancelets • tiny marine animals • retain all 4 characteristics into adulthood • led to vertebrates

  5. SUBPHYLUMVERTEBRATA

  6. Characteristics of Vertebrata • Vertebral column • Neural crest • pronounced cephalization • closed circulatory system

  7. FISH • 5 Classes • 1st vertebrates, aquatic • Generally characterized by scales, fins and pharyngeal gills • Ectothermic – no internal body temperature regulation

  8. Circulation • closed circulatory system with a 2 chambered heart. Reproduction • reproduce through external fertilization - spawning

  9. Jawless Fish – Superclass Agnatha • Hagfish (Class Myxini) and Lampreys (Class Cephalaspidomorphi) • Lack vertebrae (hagfish) or have incomplete vertebral column (lamprey) • Predators that attach to the side of a fish with modified mouth • Have no scales

  10. Cartilage fish • Class Chondrichthyes • Sharks, skate, rays and sawfish • Primitive Older fish • Most have to swim to breathe • Have cartilage skeletons • Acute senses and lateral line

  11. Bony Fish • Ray finned fish (Class Actinopterygii ) - most common fish - have jaws and paired fins - fins supported by rays fanning out from central bone

  12. Lobe finned fish (Class Sarcopterygii) - fins supported by central axis bone - coelacanths - ancestors of amphibians - can walk on fins

  13. Class Amphibia • Frogs and salamanders • Aquatic as larvae, after metamorphosis, live on land as adults. • Have moist skin with many glands • must be moist to breathe; respirate through skin • evolved from fish 360 mya • ectothermic

  14. Circulation • Amphibians have a double-loop circulatory system with three-chambered heart. Reproduction • Fertilization is external • Shell-less eggs must be laid and fertilized in water

  15. Class Reptilia • Include 3 groups: snakes, turtles, crocodiles • Fully adapted to life on land • Amniotic egg • Scaly keratinized skin (prevents loss of moisture) • Ectothermic - regulate their body temperatures by basking in the sun, burrowing in the ground. Soaking in water etc…

  16. Circulation • more efficient circulatory and respiratory systems (lungs, 3 chambered heart). Reproduction • internal fertilization • Lay fluid filled amniotic egg covered with a protective shell

  17. Class Aves • Most are adapted for flight • Covered with feathers • hollow (honeycombed) bones • 2 legs for walking, 2 modified for wings • Birds are endothermic - generate body heat internally by their own metabolism.

  18. Circulation 4 chambered heart; allows for efficient delivery of O2 to cells. Reproduction • internal fertilization. • incubate eggs and feed young • have amniotic eggs (keeps eggs moist)

  19. Fossil evidence shows that birds evolved from the same line as crocodiles and dinosaurs.

  20. Class Mammalia Characteristics: • hair made of keratine - insulation, camouflage, sensory device, waterproofing, signaling and defense • mammary glands • Endothermic

  21. Circulation • 4 Chambered heart • Require a constant supply of nutrients and oxygen to maintain homeostasis and metabolism • Keeping blood separate makes the delivery of nutrients and oxygen more efficient. Reproduction • Internal fertilization

  22. 3 Types • Monotremes- young develop in shelled eggs; • Ex. spiny anteater and duck-billed platypus 2. Marsupial - young leave mother’s body to pouch before development is complete. Ex. kangaroo and opossum 3. Placental - young develop completely within the uterus of the female Ex. Human, whales, giraffe etc…

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