To the Land and Back • 350 MYA - Tetrapods evolve from fish • Need: • Lungs • Forelimbs • Ability to avoid drying out • Some move back to the oceans - new adaptations required
Sea Turtles • Enclosed by carapace • Cannot retract head • Flippers • Return to land to reproduce after long migrations • All threatened to endangered
Sea Snakes • Tropical Indian and Pacific • Laterally compressed • Ovoviparous • Small mouth but highly venomous
Marine Iguanas • Galapagos • Live in large colonies • Herbivores • Salt glands in nose
Saltwater Crocodile • Very large (usually max of 20 ft.) • Usually found in coastal areas • Highly aggressive
Seabirds • Homeothermic / Endothermic • Oil glands • Feathers • Light, hollow bones • Hard egg shell But can they do this??!!
Penguins • Flightless • Denser bones (reduces buoyancy) • Layer of fat plus feathers for warmth • Southern hemisphere • Mating practices
Tubenoses • Heavy curved beak • Mostly open sea predators • Elaborate courtship followed by lifelong pairing • Albatrosses, shearwaters, petrels
Pelicans and Relatives • Webbing between toes • Fish eaters
AUKS!! • Common name for the Alcids • May fill penguin niche in Northern Hemisphere • Puffins, razorbills, guillemots, dovekies (little auks) • Great auk extinct in 1844
Shorebirds • Herons, egrets, plovers, etc. • Found on coastlines usually for feeding • Often common in freshwater
Marine Mammals • Endothermic/Homeothermic • Hair and mammary glands • Viviparous and placental • Large, complex brain
Pinnipeds • Relatives of Carnivora • Blubber and fur • Seals, sea lions and walruses
Carnivora - Polar Bears • Arctic top predators • Swim well but hunt on ice (seals, belugas, etc.) • Parental care
Carnivora - Sea Otters • Smallest marine mammal • Lacks blubber but dense fur • Eat a LOT! (Mostly inverts) • Parental care • Still threatened
Sirenians • Manatees and dugongs • No rear limbs • Paddle shaped tail • Thick blubber layer but almost no hair • Four remaining species (all endangered)
Cetaceans • Largest group of marine mammals • Entirely aquatic • Convergent evolution
Respiration • Nasal drift • Rapid air movement • 90% oxygen delivery from lungs! • Blood adaptations: • Greater blood volume • More erythrocytes with more hemoglobin • Extra myoglobin in muscles • Lowered HR and restricted blood flow • Lung collapse?? Exhalation before diving?? Why??
Echolocation • Toothed whales, some pinnipeds and baleen whales
It’s cold down there!! • Blubber - useful as insulation and as energy reserve • Fur in pinnipeds and carnivora • Blood vessels in whale tongues transfer heat back to core
Vocalization What purpose does it serve?
Reproduction - Cetaceans • Copulation in water • Competition and cooperation • Sex play • 11-12 month gestation • Birth • Maternal care
Reproduction - Pinnipeds • Monogamy vs. polygamy • Harems and bachelor groups • Maternal care • Variation in nursing period • Females return • Delayed implantation allows birth to coincide with return to shore