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Marine Mammals

Marine Mammals. The Charismatic Megafauna. Tetrapod Invasion. 350 mya vertebrates invaded land Dealt with multiple stresses on land lost structural support from water Breathe air Desiccation. Led to new adaptations

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Marine Mammals

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  1. Marine Mammals The Charismatic Megafauna

  2. Tetrapod Invasion • 350 mya vertebrates invaded land • Dealt with multiple stresses on land • lost structural support from water • Breathe air • Desiccation • Led to new adaptations • Developed walking and crawling apendages – two pair of limbs=tetrapods • Evolved lungs • Water proof eggs, skin, internal young,

  3. Amphibians never fully adapted to terrestrial life • Must still stay close to water • Reptiles evolved from a now extinct line of amphibians • Birds and mammals evolved from different lines of extinct reptiles • After adapting to life on land, different groups of birds reptiles and mammals reinvaded the oceans.

  4. Reptiles • Poikilotherms(body temp varies with environment) and ectotherms(lose body heat to environment) = cold blooded • Sea Turtles • Carapace (shell) fused to backbone • Cannot retract their head into shells • 9 species of sea turtle • Prefer warmer waters

  5. Snakes and Iguanas • Sea snakes • 55 species mostly ovoviviparous • Venomous • overexploited for skins • Marine iguanas - Galapagos • Saltwater crocodile

  6. Seabirds • Homeotherms(able to keep body temp constant) and endotherms(retain metabolic heat) • Waterproof feathers • Oil gland at base of tail - preening

  7. Mammals • Order Pinnipedia • Seals, sea lions, walrus • Paddle shaped flippers • Rest and reproduce on land • Prefer colder waters • Blubber • Thick layer of subcutaneous fat • Insulation, food reserve, buoyancy

  8. Seals Sea lions • Largest group of pinnipeds • Rear flippers can’t be moved forward • Feed on fish and squid • Related to fur seals • Have external ears • Can move rear flippers forward • Feed on fish and squid

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