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Vertebrates

Vertebrates. Mammal evolution. Originated in the ocean Land vertebrates descended from bony fishes On land, evolved 2 pair of limbs = tetrapods (4 footed) and lungs. Some amphibians evolved into reptiles, some reptiles into mammals or birds

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Vertebrates

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  1. Vertebrates Mammal evolution

  2. Originated in the ocean • Land vertebrates descended from bony fishes • On land, evolved 2 pair of limbs = tetrapods (4 footed) and lungs

  3. Some amphibians evolved into reptiles, some reptiles into mammals or birds • At some point, land tetrapods reinvaded the ocean = marine tetrapods

  4. Marine Mammals • Evolved from reptiles about 200 million years ago

  5. Overshadowed until dinosaurs disappeared 65 million years ago

  6. 4500 species of mammals • Endotherms (warm-blooded) • Have hair on their skin • In relation to body size, brain is larger and more complex than in reptiles

  7. Viviparous – bear young that are developed inside the mother’s body • Baby mammals feed on mother’s milk

  8. Pinnipeds • Seals • Sea Lions • Walruses

  9. Seals • Largest group of pinnipeds (seals, sea lions, and walruses) • 19 different species

  10. Evolved from early terrestrial carnivores and are kin to cats, dogs, and bears

  11. Rest, breed, and bear young on land • Land-breeders – form a “harem” with a large lead male

  12. Ice-breeders – are monogamous and similar in size

  13. Bristly hair on body and face • No external ear • Short neck • No external testicles in males

  14. Predators – feed mostly on fish and squid • Nostrils close automatically and pupils expand widely under water • Can remain under water for 1-2 hours due to large spleen storing oxygen-rich blood

  15. Flippers • Paddle-shaped for swimming • Rear flippers do not move forward, so they cannot “pull” themselves onto land

  16. Anterior flippers covered with hair, 5 toes with sharp nails, and cannot be rotated backward

  17. Most live in cold water • Thick blubber – keeps them warm, helps with buoyancy, and serves as food reserve for weeks

  18. Hunted for their skin, meat, and oil from their blubber • Make and hear sounds under water used for simple communication (from barks and wails to complex songs) • Still unknown if use reflected sound waves or echolocation for underwater navigation and to track prey

  19. Elephant Seal • Largest of pinnipeds – up to 20 ft. and 4 tons (The Internet is full of recent data.)

  20. Named for large proboscis of male

  21. Almost exterminated for their blubber, and only 100 remained in 1890 • Because of protection, almost 100,000 now on California’s coast

  22. Monk Seal • Live in warm regions • Rare • Endangered • Carribean Monk Seal – last seen in 1952

  23. Harp Seal • Give birth to white, furry pups on floating Arctic ice • Pups grow fast and shed fur before ice melts

  24. Pups used to be clubbed to death in Newfoundland for their fur…now suspended

  25. Animals: Sleeping Sea Lion Sea Lions

  26. Rear flippers can move forward, so they can walk and run on land

  27. Uses front flippers in swimming – no hair or nails on the edge • Front flippers can rotate backward to help support weight and keep head up • External testicles present in males

  28. Have external ears • Have a longer neck than seals so can support their head upright

  29. Graceful and agile swimmers using mostly their broad front flippers (seals use their back flippers to swim)

  30. Bulls (males) are much bigger than cows (females)

  31. Sea lions look more dog-like, whereas seals look more cat-like

  32. Fur Seals • 9 species • Really sea lions with a thick underfur

  33. California Sea Lion • Most familiar fur seal • Found off the Pacific US coast and Galapagos Islands

  34. Trained “barking seals” you see do tricks at Sea World

  35. Once almost wiped out for their fur

  36. Walrus • Large with a pair of tusks • Stiff whiskers on snout act as feelers when eating

  37. Mostly eat clams and bottom invertebrates • Suck their food into their mouths as they move along the bottom

  38. Habitat is on the edges of the ice pack in the Arctic • Migrate south during winter • Hunted legally by natives

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