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31.3 Vertebrates (cont’d)

31.3 Vertebrates (cont’d). Amphibians, Reptiles, and Mammals. Amphibians. About 6,600 species Live on both land and water ( = amphi ) Include frogs, toads, newts, salamanders Differences from fishes: jointed appendages four limbs eyelids (keep eyes moist) voice-producing larynx

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31.3 Vertebrates (cont’d)

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  1. 31.3 Vertebrates (cont’d) Amphibians, Reptiles, and Mammals

  2. Amphibians • About 6,600 species • Live on both land and water ( = amphi) • Include frogs, toads, newts, salamanders • Differences from fishes: • jointed appendages • four limbs • eyelids (keep eyes moist) • voice-producing larynx • lungs (although many adults breathe through their skin) • 3-chambered heart

  3. Reptiles • About 15,000 species • Include many extict species, including dinosaurs • Include snakes, lizards, alligators, turtles and birds

  4. Reptiles (continued) • Adaptations to land life: • Hard scales • Tongue as sense organ • 3 or 4-chambered heart (incomplete septum in ventricles in some species) • Sexual reproduction is direct (sperm directly deposited into female and fertilization takes place internally in the female) • Amniotic egg produced is typically leathery, flexible and shelled • Most are ectothermic (cold-blooded)

  5. Birds (continued) • Birds are actually feathered reptiles • Differences b/t birds and other reptiles: • Endothermic (warm-blooded) • Hard-shelled eggs • Feathers • Septum in ventricle complete (4-chambered heart)

  6. Mammals • Evolved from reptiles • About 4,600 species • Mammalian groups include: • Monotremes • Lay hard-shelled eggs • Include spiny anteater and duckbill platypus (both found in Australia) • After hatching, remain in burrow where they are nursed for up to 2 months

  7. Mammals (continued) • Marsupials • Begin development inside female’s body • Born immature and finish developing in a pounch in mother’s abdomen • Attach there to nipples of mammary gland and continue development • Mainly found in Australia • Underwent adaptive radiation there w/o competition with placental mammals • Include koalas, kangaroos, Tasmanian devil,

  8. Mammals (continued) • Placental mammals • Vast majority of mammals • Extraembryonic membrane adapted for internal development within the uterus • Attachment to placenta through umbilical cord (allows for nutrient, gas and waste exchange b/t mother and fetus’ blood) • Extremely well-adapted to life on land (hair, large lungs) • Very developed brain • Differentiated teeth

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