4 Defining Characteristics

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. Three Subphylum • Urochordata • Tunicates • Cephalochordata • Lancelets • Vertebrata • Fish • Amphibians • Reptiles • Birds • Mammals

4. SUBPHYLUM UROCHORDATA • Tunicates • “Tail Cords” – over 2,000 species • Adults sessile • Free swimming larvae; only larvae have a 4 defining characteristics

5. SUBPHYLUM CEPHALOCHORDATA • Lancelets • “Head-Cords” • tiny marine animals • retain all 4 characteristics into adulthood • Notochord, pharyngeal slits, dorsal hollow nerve cord, post anal tail • led to vertebrates • Filter Feeders

6. SUBPHYLUM VERTEBRATA

7. Fish • 5 Classes • 1st vertebrates, aquatic • Generally characterized by scales, fins and pharyngeal gills • Exothermic (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 • Hagfish (Class Myxini) and Lampreys (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. Hagfishno vertebraehas a skull

11. Class Chondrichthyes • Cartilage fish • Sharks, skate, rays and sawfish • Primitive Older fish • Most have to swim to breathe

12. Bony Fish • Ray finned fish (Class Actinopterygii ) - - most common fish - have jaws and paired fins - fins supported by rays fanning our from central bone • Lobe finned fish (Class Sarcopterygii) - fins supported by central axis bone - ancestors of amphibians

13. Walking Fish - Grunion

15. Class Amphibia • Frogs and salemanders • 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 • exothermic

16. 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

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

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

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

22. 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)

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

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

26. 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

27. 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…