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The Diversity of Chordates: From Fish to Mammals

Explore the defining characteristics and evolution of chordates, spanning from subphylum Urochordata to class Mammalia, including fish, amphibians, reptiles, birds, and mammals. Discover the unique features and adaptations of each group.

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The Diversity of Chordates: From Fish to Mammals

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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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